Hormone Therapy

Micronised Progesterone

Bioidentical progesterone for hormonal sleep disruption, perimenopausal and menopausal symptoms, and cyclical mood symptoms.

Medication
oral capsule, troche, or topical cream
Target dose
Titration
Clinician-led
Last reviewed
May 27, 2026

what it is.

01 — about

Micronised progesterone is bioidentical progesterone — structurally identical to the progesterone your body produces. It differs from synthetic progestins (such as medroxyprogesterone, norethisterone, or levonorgestrel), which have different effects on mood, sleep, and the cardiovascular system. At biio., it is used for hormonal sleep disruption, perimenopausal and menopausal symptoms, cyclical mood and anxiety symptoms (including PMDD patterns), and as part of hormone therapy where oestrogen-related symptoms also affect MCAS or POTS patterns.

The micronised progesterone you are prescribed is a compounded medication dispensed by a compounding pharmacy. biio. uses compounded troches, capsules, or creams depending on the indication. This allows the dose, route, and timing to be tailored to your phenotype — for example, oral or troche use leverages the sedating metabolites that support sleep, while transdermal use minimises systemic sedation for daytime indications.

Compounded micronised progesterone is off-label for several of the indications it is used for at biio. The registered oral formulation (Prometrium) is registered for menopausal hormone therapy alongside oestrogen and for some IVF contexts.

how it works.

02 — mechanism

Progesterone acts on progesterone receptors throughout the body, including the central nervous system, breast tissue, uterus, and cardiovascular system. Two effects matter most for the indications biio. uses it for.

The first is direct progesterone receptor activity, which counterbalances the effects of unopposed oestrogen — relevant for cyclical symptoms, perimenopausal patterns, and combined hormone therapy.

The second is the effect of allopregnanolone, a progesterone metabolite produced when progesterone is taken orally or as a troche. Allopregnanolone is a positive modulator of the GABA-A receptor, which is why oral progesterone has a calming, sleep-supporting effect that transdermal progesterone does not have to the same extent. The sedating effect at the biio. dose is intentional when used for sleep; it is also the reason oral dosing is at night and not in the morning.

In MCAS patients with a clear pattern of oestrogen-driven flares, micronised progesterone can sometimes reduce the cyclical worsening — although the evidence here is clinical rather than trial-based, and the response is individual.

PROGESTERONE RECEPTOR ACTIVITY

Acts on progesterone receptors throughout the body, counterbalancing the effects of unopposed oestrogen.

ALLOPREGNANOLONE & GABA-A

Oral or troche use produces allopregnanolone, a positive modulator of the GABA-A receptor, giving a calming, sleep-supporting effect.

ROUTE-DEPENDENT EFFECTS

Oral and troche routes leverage the sedating metabolites that support sleep, while transdermal use minimises systemic sedation for daytime indications.

CYCLICAL FLARE SUPPORT

In MCAS patients with oestrogen-driven flares, it can sometimes reduce cyclical worsening, though the response is individual.

how to take it.

03 — daily routine

Micronised progesterone is dispensed as one of three formulations:

  • Oral capsule — swallowed whole with water, taken at night, ideally with a small amount of food.
  • Sublingual or buccal troche — held in the mouth (under the tongue or against the cheek) and allowed to dissolve over 10–20 minutes. Do not chew or swallow whole — the route changes the metabolism.
  • Topical cream — applied to thin-skinned areas (inner wrist, inner thigh, behind the knee) rotating sites to minimise local saturation.

Specific instructions for your formulation:

  • Oral and troche doses are taken at night because of the sedating allopregnanolone effect. Do not take in the morning unless biio. has specifically directed this.
  • Allow at least 1 hour after a meal containing significant fat for oral capsules, or take with a small low-fat snack — fat increases absorption and can amplify sedation.
  • Cream is usually applied once or twice daily depending on protocol. Apply to clean, dry skin. Wash hands after application. Do not transfer cream to children, pets, or partners by skin contact.
  • Store as directed by your compounding pharmacy. Cream often requires refrigeration; capsules and troches usually do not.
  • Cyclical dosing (e.g. days 14–28 of your cycle) and continuous dosing serve different purposes — follow the schedule biio. has set.

starting & adjusting your dose.

04 — titration
clinician-led titrationadjust only on biio. instruction — never self-titrate

Starting dose and titration. This is clinician-led titration. Do not increase your dose without instruction from biio. — the appropriate dose depends on the indication, your cycle status, and whether oestrogen is also being prescribed.

Typical starting doses by indication:

  • Sleep and hormonal sleep disruption: oral capsule or troche 100 mg at night. Increase to 200 mg at night after 2–4 weeks if 100 mg is tolerated and the target outcome is not yet held.
  • Perimenopausal symptoms with retained cycle: cyclical dosing on the second half of the cycle (days 14–28), 100–200 mg at night.
  • Menopausal hormone therapy alongside oestrogen: continuous 100 mg at night, or cyclical 200 mg at night for 12 days each month depending on the regimen biio. has set.
  • PMDD-pattern cyclical mood: troche 100–200 mg in the luteal phase, exact schedule individualised.
  • Topical cream: dose varies by indication and the strength of the compounded preparation; follow the specific prescription.

Do not increase the dose between clinical reviews. If the starting dose is poorly tolerated, contact biio. before continuing or stopping.

Reducing the dose. If sedation is excessive (you are not waking refreshed, or daytime drowsiness extends past mid-morning), reduce to the previous tolerated dose for 2 weeks. If breast tenderness is significant, reduce to the previous dose and contact biio.

Starting dose
100 mg at night

Clinician-led; at night

Target dose

Maximum

Reducing the dose

If sedation, brain fog, or blood-pressure drops are bothersome, reduce by one step — 50 mcg — and hold there for 7 days before reassessing. Do not reduce more than one step at a time without biio. input.

stopping the medication.

05 — tapering

Stopping the medication. Micronised progesterone can be stopped without tapering in most cases. If you have been on continuous high-dose therapy for longer than 6 months, biio. may recommend stepping down over 4–6 weeks rather than stopping abruptly — the return of unopposed cyclical symptoms can otherwise be uncomfortable. If you are on combined hormone therapy with oestrogen, do not stop progesterone alone while continuing oestrogen — the two are stopped together or under biio. guidance.

Missed a dose?

For oral or troche dosing at night: if you miss a dose and remember within a few hours of bedtime, take it. If it is already the morning, skip it — taking it in the morning will produce daytime sedation. Do not double up the following night. For cream: if you miss a daily application, apply it as soon as you remember unless it is close to the next dose. Skip the missed dose if it is nearly time for the next one. For cyclical schedules: if you miss multiple days, contact biio. — the cycle pattern matters and may need adjusting rather than catching up.

what to expect.

06 — timeline & markers

The effects unfold over different timescales depending on the indication.

  • Sleep effects: usually noticeable from the first or second night. Falling asleep faster and waking less frequently are the most common changes.
  • Mood and anxiety effects: usually emerge over 2–8 weeks of consistent use. For cyclical patterns, you will not be able to assess the effect until you have been through at least 2 full cycles.
  • Perimenopausal symptoms (hot flushes, night sweats, sleep disruption): partial improvement within 2–4 weeks, full effect by 8–12 weeks.
  • Breast tenderness is common in the first 2–4 weeks and usually settles. Persistent breast tenderness should be reviewed.
  • Spotting or breakthrough bleeding is common in the first 2–3 months of any hormone therapy regimen. Persistent bleeding beyond 3 months warrants review.

If you have completed 3 months at a stable dose with no measurable change in the symptoms it was prescribed for, contact biio. before continuing — the dose, formulation, or schedule may need adjustment.

side effects — what to do.

07 — three tiers

Most side effects are mild and settle as your body adapts. Use the three tiers below to decide what to do. When in doubt, lean toward the middle tier — call biio. and we will help.

01

common & usually self-manageable.

Manage at home
Mild local irritation at the cream application site

Rotate sites. If irritation persists, contact biio. — the compounded base may need adjusting.

Spotting or breakthrough bleeding in the first 2–3 months

Track the pattern and report at your review.

Headache

Common in the first week. Paracetamol is appropriate. Usually settles.

Mood changes — usually settling or calming, occasionally low mood

Mild low-mood effects in the first 2 weeks usually settle. If mood worsens significantly and persistently, contact biio.

Mild bloating or fluid retention

Common in the first 4 weeks. Usually settles. Reduce added salt for a few days if marked.

Breast tenderness

Common in the first 2–4 weeks. Wear a supportive bra. Reduce caffeine, which can worsen breast tenderness. Usually settles by week 6.

Drowsiness or grogginess after the evening dose

Expected with oral or troche dosing. If it is excessive and persisting into the morning, reduce to the previous dose for 2 weeks. Take the dose 30 minutes earlier if morning grogginess is the main issue.

02

worth a call to biio.

Contact us
Considering pregnancy

You are considering pregnancy.

New medication prescribed by another clinician

New medication prescribed by another clinician.

New onset cyclical headache or worsening migraine

New onset of cyclical headache or worsening migraine pattern.

Breakthrough bleeding beyond 3 months or new bleeding

Breakthrough bleeding persisting beyond 3 months, or any new bleeding that starts after a stable period without bleeding.

Persistent breast tenderness beyond 6 weeks

Persistent breast tenderness beyond 6 weeks at a stable dose.

Mood worsening

Mood worsening — increased anxiety, low mood, or irritability that does not settle within 4 weeks.

Excessive daytime drowsiness persisting beyond 2 weeks

Excessive daytime drowsiness persisting beyond 2 weeks at a stable dose.

03

seek urgent care.

Act immediately
New vaginal bleeding after 12 months without periods

(post-menopause): do not stop the medication, but contact biio. on 1800 325 205 within the next few days and book a review. Post-menopausal bleeding always requires assessment.

Severe abdominal pain with vomiting, or new yellowing of skin or eyes

stop the medication and seek urgent medical review — possible liver event.

Signs of stroke or TIA

sudden weakness on one side, sudden speech difficulty, sudden vision change, severe sudden headache: call 000.

Signs of venous thromboembolism

calf pain, swelling, warmth in one leg; sudden shortness of breath; chest pain on breathing in; coughing blood: stop the medication and present to the nearest ED. Risk is lower with micronised progesterone than with synthetic progestins, but it is not zero, particularly when combined with oestrogen.

Severe allergic reaction

(hives, facial swelling, throat tightening, difficulty breathing): stop immediately and call 000.

interactions.

08 — what to flag
Medication or contextRuleWhat to know
Other medications that increase hyponatraemia risk
SSRIs/SNRIs, carbamazepine, some tricyclic antidepressants, NSAIDs, diuretics (frusemide, spironolactone, hydrochlorothiazide), and some antipsychotics
Inform biio.

all lower sodium or impair sodium regulation. Combining these with desmopressin increases the risk of hyponatraemia substantially. Inform biio. if you are on any of these medications.

Oestrogen and progesterone therapy
Oversight

DHEA is converted to oestradiol and testosterone in peripheral tissues. If you are also on oestrogen or progesterone (HRT, oral contraceptives), biio. will manage the dose carefully — sometimes a lower DHEA dose is appropriate.

Renal impairment
Inform biio.

Famotidine is primarily renally cleared. If eGFR is below 50, the dosing interval should be increased (e.g. 20 mg every 48 hours instead of daily). Inform biio. of any new kidney diagnosis.

Fruit juices
grapefruit, orange, apple
Avoid

Reduce fexofenadine absorption substantially. Take with water only; separate from juice by at least 2 hours.

Alcohol and CNS depressants
benzodiazepines, sleeping medications, opioids
Caution

Additive sedation. Avoid alcohol until you are on a stable dose and know its effect. Use other sedating medications with caution alongside cetirizine.

Other blood pressure medications and antihypertensives
beta blockers, calcium channel blockers, ACE inhibitors, ARBs
Monitor

Additive blood pressure lowering. Combinations require blood pressure monitoring. Particular caution with beta blockers: if clonidine is stopped abruptly in someone also taking a beta blocker, rebound hypertension can be severe. If both are being discontinued, clonidine should be tapered first.

Warfarin (anticoagulant)
Monitor

Case reports exist of CoQ10 affecting INR. If you take warfarin, have your INR checked within 1–2 weeks of starting or stopping CoQ10, and inform biio. and your anticoagulation clinician.

Kidney disease
Oversight

Creatine supplementation raises creatinine — a by-product of phosphocreatine breakdown — which can make kidney function tests appear worse even when the kidneys are not impaired. If you have known kidney disease or reduced eGFR, inform biio. before starting creatine — the decision to supplement requires clinical review, and baseline and follow-up creatinine may need monitoring.

LDN, antihistamines, desmopressin, fludrocortisone, midodrine, ketotifen, montelukast
No issue

No known significant interactions — all commonly co-prescribed at biio. Because cromolyn sodium is minimally absorbed from the gut, it has very few systemic drug interactions.

Alcohol
Avoid

Alcohol inhibits DAO enzyme activity in the gut — both the DAO your body produces and supplemental DAO. Avoid alcohol if using DAO enzyme before a meal, as it directly reduces the supplement's effectiveness.

Potassium-depleting diuretics
frusemide, hydrochlorothiazide, chlorothiazide
Inform biio.

Additive potassium loss. This combination significantly increases hypokalemia risk. Inform biio. if another prescriber adds a diuretic.

CYP3A4 inhibitors
ketoconazole, itraconazole, ritonavir, clarithromycin, erythromycin, grapefruit juice
Oversight

Increase guanfacine exposure significantly. biio. may need to halve the dose during a course of these medications.

Strong CYP3A4 inhibitors
itraconazole, ketoconazole, voriconazole; clarithromycin, telithromycin; diltiazem and verapamil; grapefruit juice
Avoid

Do not combine with ivabradine. Antifungals: itraconazole, ketoconazole, voriconazole. Macrolide antibiotics: clarithromycin, telithromycin (note: azithromycin is usually acceptable — confirm with biio.). Calcium channel blockers: diltiazem and verapamil (not amlodipine — that is usually acceptable). Grapefruit juice increases ivabradine exposure significantly — avoid entirely while taking ivabradine. If a CYP3A4-inhibiting antibiotic is prescribed for an acute infection (e.g. clarithromycin for chest infection), discuss with biio. before starting — it may be necessary to temporarily stop ivabradine or choose an alternative antibiotic.

QT-prolonging medications
including some antihistamines, antidepressants, antipsychotics, macrolide antibiotics, and antifungals
Inform biio.

There is a theoretical interaction risk. If a new QT-prolonging drug is prescribed by another clinician, inform biio. before starting it. Do not combine without review.

Ketoconazole, erythromycin, and other CYP3A4/2D6 inhibitors
No issue

These can mildly increase loratadine blood levels, but the clinical significance is low at standard doses. No dose adjustment is typically needed.

CYP3A4 inhibitors
ketoconazole, itraconazole, ritonavir, clarithromycin, erythromycin
Inform biio.

Increases aripiprazole exposure. Dose reduction may be needed during a course. Inform biio.

All opioid medications
codeine, oxycodone, morphine, tramadol, buprenorphine, fentanyl, and others
Avoid

Do not combine unless you have discussed this with your prescriber. LDN will block their analgesic effect and may precipitate withdrawal symptoms. If another prescriber starts you on an opioid, ensure they are aware you are currently taking LDN. It is possible to use opioids and LDN together, however the timing needs to be discussed with your prescriber to ensure no interactions. Please note that if you decide to use 'party drugs', these may contain unknown opioid medications and it is advised not to mix these with LDN.

Agomelatine (an antidepressant used for depression, anxiety and sleep regulation)
Oversight

Binds to MT1 and MT2 receptors, combining with melatonin requires caution as excessive drowsiness can occur. If you take agomelatine, your melatonin dose should be very low (0.5 mg or less) and reviewed with biio. Do not take standard melatonin doses alongside agomelatine without clinical guidance.

MAO inhibitors (MAOIs)
Avoid

Contraindicated. The combination can cause severe hypertensive crisis, headache, and cardiovascular collapse. Inform every prescriber that you take methyldopa. If an MAOI is prescribed, contact biio. immediately.

Oestrogen
oral, transdermal, vaginal
Oversight

When prescribed together as combined hormone therapy, the progesterone is essential — it protects the uterine lining. Do not stop progesterone while continuing oestrogen.

MAO inhibitors (MAOIs)
phenelzine, tranylcypromine, selegiline, and the antibiotic linezolid
Avoid

Do not combine with midodrine. This combination can precipitate a severe hypertensive crisis. If an MAOI is prescribed by any clinician, inform biio. immediately on 1800 325 205.

CYP2C8 inhibition
Inform biio.

Montelukast inhibits the CYP2C8 enzyme, which is involved in the metabolism of some medications. This is unlikely to be clinically significant for most biio. patients, but if you are prescribed a new medication — particularly ones broken down via cytochrome P450 pathways — inform biio.

Other nicotine products
cigarettes, vapes, nicotine gum, nicotine lozenges, snus
Avoid

Do not combine. The combined nicotine dose can produce toxicity. If you start a patch trial, you must not use any other nicotine product.

Renal impairment
Inform biio.

Nizatidine is renally cleared. If eGFR is significantly reduced, dose adjustment is needed. Inform biio. of any new kidney diagnosis.

Fludrocortisone
Oversight

Promotes renal sodium retention. When fludrocortisone and oral electrolyte supplementation are used together — as they commonly are in POTS management — the effect is additive. Your sodium and fluid targets need to be set with both in mind; taking standard electrolyte targets on top of fludrocortisone without clinical review increases the risk of fluid overload and oedema. Ensure biio. knows you are on both.

Anticoagulants
warfarin, apixaban, rivaroxaban, dabigatran
No issue

No clinically significant interaction documented. PEA does not have anti-platelet effects.

Oestrogen
oral, transdermal, vaginal
Oversight

When prescribed together as combined hormone therapy, the progesterone is essential — it protects the uterine lining. Do not stop progesterone while continuing oestrogen.

Asthma and reactive airways disease
Avoid

Propranolol is contraindicated. If there is any history of asthma or bronchospasm, confirm with biio. before use.

Neuromuscular blocking agents used in anaesthesia
pancuronium, rocuronium, vecuronium
Plan ahead

Pyridostigmine significantly interacts with non-depolarising neuromuscular blocking agents, affecting their dose requirements and duration. You must inform your anaesthetist and surgical team that you take pyridostigmine before any procedure requiring general anaesthesia. Ideally, contact biio. in advance to discuss whether to pause pyridostigmine around the time of surgery.

Oral medications generally
Inform biio.

Semaglutide slows gastric emptying, which may alter the absorption of some oral medications. Most medications are not clinically affected, but inform biio. of any narrow-window oral medication you take, such as ADHD medications.

Oral medications generally
Inform biio.

Tirzepatide slows gastric emptying, which may alter the absorption of some oral medications. Most medications are not clinically affected, but inform biio. of any narrow-window oral medication you take.

Oestrogen and progesterone therapy
Oversight

Topical testosterone is often used alongside HRT in post-menopausal women. biio. will manage the regimen as a whole.

Fludrocortisone
Oversight

Also affects sodium and fluid retention. Both are sometimes used together in POTS management, but the combination increases risk of fluid overload and hyponatraemia — this combination requires clinical oversight. Do not combine without explicit biio. instruction.

Tamoxifen and aromatase inhibitors
Avoid

DHEA can be converted to oestrogen and may interfere with the intended effect of these medications. Do not combine without specialist agreement.

Proton pump inhibitors
esomeprazole, pantoprazole, omeprazole
Plan ahead

Reflux medications such as esomeprazole, pantoprazole and omeprazole can be used with famotidine, however doses may need to be staggered. Discuss this with your biio. prescriber.

Aluminium- or magnesium-containing antacids
Plan ahead

Reduce fexofenadine absorption. Separate by at least 2 hours.

Theophylline
Inform biio.

High doses of theophylline can reduce cetirizine clearance, potentially increasing sedation. If theophylline is prescribed, inform biio.

Tricyclic antidepressants (TCAs)
amitriptyline, nortriptyline
Inform biio.

These can reduce the blood pressure-lowering effect of clonidine. Inform biio. if a TCA is prescribed.

Statins
atorvastatin, rosuvastatin, simvastatin
No issue

Statins reduce endogenous CoQ10 production in the liver. Supplemental CoQ10 is sometimes used alongside statins for this reason — there is no adverse pharmacokinetic interaction and the combination is safe.

NSAIDs (ibuprofen, naproxen) and diuretics
ibuprofen, naproxen
Inform biio.

These can reduce kidney clearance of creatinine. Combined use with creatine may produce more significant creatinine elevation on blood tests, which can confuse monitoring. Inform biio. if you use NSAIDs regularly.

Renal or hepatic impairment
Inform biio.

Dosing should be reviewed if you develop significant kidney or liver disease, as elimination may be affected. Inform biio. of any new diagnoses.

High-dose vitamin C (ascorbic acid)
Caution

May inhibit DAO activity in some people. Avoid very high-dose vitamin C supplementation if you are using DAO enzyme and not achieving expected benefit.

Desmopressin
Oversight

Both affect sodium and fluid balance. The combination requires clinical oversight and carries increased risk of fluid overload or electrolyte disturbance. Do not combine without explicit biio. instruction.

CYP3A4 inducers
carbamazepine, phenytoin, rifampicin, St John's wort
Oversight

Reduce guanfacine effectiveness. May need higher doses of guanfacine.

Moderate CYP3A4 inhibitors
fluconazole, some HIV medications
Inform biio.

Inform biio. and your pharmacist — dose reduction may be needed.

Sedating medications and alcohol
Caution

Ketotifen has additive sedating effects with other CNS depressants — alcohol, benzodiazepines, sleeping medications, opioids, and some antihistamines. Avoid alcohol until you know how ketotifen affects you. If combining with other sedating medications, do so with caution and only after discussion with biio.

Alcohol
Caution

Loratadine is non-sedating and does not significantly interact with alcohol — but alcohol itself is a histamine liberator and a common MCAS trigger. Use with awareness.

CYP2D6 inhibitors
fluoxetine, paroxetine, bupropion
Inform biio.

Increases aripiprazole exposure. Inform biio.

Thyroid hormone medication
thyroxine, T3, T3/T4 combinations
Monitor

LDN may increase sensitivity to thyroid hormone in some people. If you take thyroid medication, monitor for signs of over-replacement — palpitations, tremor, sweating, anxiety — and report these to biio.

Fluvoxamine (an antidepressant used for OCD and anxiety)
Oversight

Dramatically increases melatonin blood levels — by up to 17-fold — by inhibiting the CYP1A2 enzyme that metabolises melatonin. If you take fluvoxamine, your melatonin dose should be very low (0.5 mg or less) and reviewed with biio. Do not take standard melatonin doses alongside fluvoxamine without clinical guidance.

Oral iron supplements
Plan ahead

Iron significantly reduces the absorption of methyldopa. Separate iron from methyldopa by at least 2 hours. Do not take together.

Anticonvulsants
phenytoin, carbamazepine, phenobarbital, oxcarbazepine, topiramate
Inform biio.

These accelerate progesterone metabolism and reduce its effect. Dose adjustment is sometimes needed — inform biio.

Alpha blockers
prazosin, terazosin, doxazosin, tamsulosin
Inform biio.

These drugs work in the opposite direction to midodrine — they dilate blood vessels. Combining them will reduce or negate midodrine's effect. Inform biio. if prescribed.

Rifampicin and other strong CYP enzyme inducers
Inform biio.

These drugs can reduce montelukast levels and reduce its effectiveness. If rifampicin or similar is prescribed, inform biio.

Caffeine
Caution

Nicotine increases caffeine metabolism — the same caffeine dose can feel less effective on a nicotine patch. The reverse can happen if you stop the patch — caffeine can feel stronger.

Proton pump inhibitors
Plan ahead

Reflux medications such as esomeprazole, pantoprazole and omeprazole can be used with nizatidine, however doses may need to be staggered. Discuss this with your biio. prescriber.

Desmopressin
Caution

Reduces fluid excretion from the kidney. On days you take desmopressin, restrict fluid intake for 8 hours after the dose — even if you are otherwise on a high fluid intake target. Large fluid intake with desmopressin significantly increases the risk of hyponatraemia. See your desmopressin factsheet for the specific instructions that apply on dose days.

NSAIDs
No issue

PEA is sometimes used to reduce reliance on NSAIDs. No direct interaction.

Anticonvulsants
phenytoin, carbamazepine, phenobarbital, oxcarbazepine, topiramate
Inform biio.

These accelerate progesterone metabolism and reduce its effect. Dose adjustment is sometimes needed — inform biio.

Calcium channel blockers
verapamil and diltiazem
Avoid

Combining with propranolol can cause severe bradycardia and heart block. Do not combine unless under the care of a cardiologist. (Amlodipine is generally safe.)

Anticholinergic medications
bladder medications such as oxybutynin, solifenacin; some antidepressants; some antipsychotics
Inform biio.

These directly oppose pyridostigmine's mechanism, reducing its effect. If an anticholinergic is prescribed, inform biio.

Levothyroxine
Monitor

Absorption may be modestly reduced; thyroid function should be checked at standard intervals.

Oral contraceptives
Caution

Manufacturer guidance suggests that for the first 4 weeks of starting tirzepatide and for 4 weeks after each dose increase, a barrier method or a non-oral contraceptive should be added to oral contraceptives, because tirzepatide may reduce oral contraceptive absorption during these windows. Confirm specific guidance with biio.

Anticoagulants
warfarin, apixaban, rivaroxaban, dabigatran
Monitor

Testosterone may modestly affect coagulation parameters. INR monitoring may need to be more frequent on warfarin.

Antihistamines (H1 and H2)
No issue

DAO and antihistamines work via entirely different mechanisms — DAO degrades histamine before absorption; antihistamines block histamine receptors after it reaches the bloodstream. The combination is rational and used at biio. There is no pharmacokinetic interaction.

Midodrine
Monitor

Commonly co-prescribed for POTS at biio. No significant pharmacokinetic interaction, but combining haemodynamic agents increases the importance of monitoring blood pressure.

Anticoagulants
warfarin, apixaban, rivaroxaban, dabigatran
Monitor

DHEA may modestly affect coagulation parameters. INR monitoring may need to be more frequent on warfarin.

Medications requiring acidic pH for absorption
atazanavir, ketoconazole, itraconazole capsules, certain oral iron preparations
Caution

Famotidine raises gastric pH and can reduce the absorption of atazanavir (HIV medication), ketoconazole, itraconazole taken as capsules, and certain oral iron preparations if taken within 2 hours. Separate these by at least 2 hours from famotidine if they are co-prescribed.

Renal impairment
Inform biio.

Cetirizine is primarily renally cleared. If your kidney function is significantly reduced (eGFR below 30), the dose should be halved to 5 mg daily or 10 mg every other day. Inform biio. of any new kidney diagnosis.

CNS depressants
benzodiazepines, sleeping medications, opioids, alcohol
Caution

Additive sedation. Use with caution. Avoid alcohol until you are established on a stable dose and know its sedating effect.

Antihypertensives
Monitor

CoQ10 has a mild blood-pressure-lowering effect in some people. If you take antihypertensives and your blood pressure is already on the lower side, monitor blood pressure when starting CoQ10 and report any significant further drop to biio.

Caffeine
Caution

High caffeine intake may partially reduce the performance benefit of creatine in some people. This is of limited clinical significance, but if you are a high caffeine user and not responding to creatine, it is worth considering reducing caffeine intake.

Food
No issue

There are no foods that interact with cromolyn sodium directly. The four-times-daily meal-linked schedule is about timing of gut protection, not pharmacokinetic interaction.

Erythromycin and ketoconazole
No issue

These increase fexofenadine blood levels (by approximately 100%), but without increasing adverse effects at standard doses. No dose adjustment is typically required.

Digoxin
Monitor

Hypokalemia from fludrocortisone can increase digoxin toxicity, potentially causing arrhythmias. If you take digoxin, strict potassium monitoring is required.

Other antihypertensives
Inform biio.

Additive blood pressure-lowering effect. If another clinician prescribes a blood pressure medication, inform biio.

Heart rate-slowing medications
beta-blockers, digoxin, amiodarone
Oversight

Combining with ivabradine increases the risk of symptomatic bradycardia. Beta-blocker combinations require clinical oversight and regular pulse monitoring.

H1 antihistamines
cetirizine, loratadine, fexofenadine, hydroxyzine
Caution

Commonly co-prescribed with ketotifen at biio. The combination does not produce a dangerous interaction, but additive sedation from hydroxyzine or first-generation antihistamines should be considered and you may be advised to time ketotifen separately.

Severe liver disease
Inform biio.

Loratadine is metabolised by the liver. If you have significant liver impairment, a dose reduction to 10 mg every other day may be needed. Inform biio. of any new liver diagnosis.

CYP3A4 inducers
carbamazepine, phenytoin, rifampicin, St John's wort
Inform biio.

Reduces aripiprazole exposure. Inform biio.

Immunosuppressant medications
methotrexate, azathioprine, cyclosporin, mycophenolate
Inform biio.

LDN's immune-modulating effects may interact unpredictably with immunosuppressants. Inform biio. and your prescribing specialist if you are on any of these.

Ciprofloxacin (an antibiotic)
Caution

Also inhibits CYP1A2 and increases melatonin levels. Short antibiotic courses with ciprofloxacin are common; if prescribed, take melatonin with caution and expect increased sedation or grogginess while on the antibiotic.

Clonidine
Oversight

Both are central sympatholytics with additive effects. If both are co-prescribed, close monitoring is required. Do not adjust or stop either without biio. oversight.

Rifampicin, rifabutin
Inform biio.

Reduce progesterone levels significantly. Inform biio. if these are prescribed.

Some antidepressants and antimalarials
Inform biio.

May increase midodrine levels and intensify side effects. If you are prescribed a new antidepressant or antimalarial (including prophylaxis), let biio. know.

LDN, antihistamines, desmopressin, fludrocortisone, midodrine, cromolyn sodium, ketotifen
No issue

These are commonly co-prescribed at biio. No clinically significant pharmacokinetic interactions with montelukast are expected.

Theophylline, clozapine, olanzapine, ropinirole, and other CYP1A2 substrates
Inform biio.

Nicotine induces CYP1A2; stopping the patch increases drug levels of these substrates. Relevant only if any of these are co-prescribed — inform biio.

Medications requiring acidic pH
Plan ahead

Nizatidine raises gastric pH and may reduce absorption of ketoconazole capsules, itraconazole capsules, atazanavir, and oral iron preparations if taken within 2 hours. Separate by at least 2 hours.

Diuretics
frusemide, spironolactone, hydrochlorothiazide
Inform biio.

These counteract sodium retention and may reduce the benefit of electrolyte supplementation. If a diuretic is prescribed by another clinician, contact biio. — your electrolyte targets will likely need adjustment.

Gabapentinoids
gabapentin, pregabalin
No issue

Often used together for neuropathic pain. No clinically significant pharmacokinetic interaction. The clinical effects are complementary.

Rifampicin, rifabutin
Inform biio.

Reduce progesterone levels significantly.

Clonidine
Plan ahead

If both are being stopped, clonidine should be tapered off before propranolol is withdrawn. Withdrawing propranolol first while still on clonidine carries risk of rebound hypertension (high blood pressure) — discuss any planned cessation of either with biio.

Corticosteroids
Caution

Long-term co-use with cholinesterase inhibitors can cause significant muscle weakness in some patients. This is most relevant if oral corticosteroids are started long-term.

Oral contraceptives
Caution

Potential for reduced absorption, particularly in the first 8-12 weeks of commencing GLP1. Do not rely on oral contraceptive pills for contraception.

Levothyroxine
Monitor

Absorption may be modestly affected; thyroid function should be checked at standard intervals.

Insulin and oral diabetes medication
Monitor

Testosterone may improve insulin sensitivity. Monitor for hypoglycaemia if you are on diabetes medication.

LDN, fludrocortisone, midodrine, desmopressin, cromolyn sodium, ketotifen, montelukast, and other standard biio. medications
No issue

No clinically significant pharmacokinetic interactions with DAO enzyme supplement.

LDN, antihistamines, montelukast, cromolyn sodium, ketotifen
No issue

No significant interactions with desmopressin expected.

Insulin and oral diabetes medication
Monitor

DHEA may modestly improve insulin sensitivity. Monitor for hypoglycaemia if you are on diabetes medication.

Loratadine, fexofenadine, cetirizine, nizatidine, LDN, ketotifen, montelukast, desmopressin, cromolyn sodium, fludrocortisone, midodrine
No issue

No clinically significant pharmacokinetic interactions with famotidine.

when to book a review.

09 — review triggers

Most patients only need contact between scheduled reviews when one of the following applies. When in doubt, send a message — we would rather hear from you early.

  • You have completed 3 months at a stable dose with no measurable improvement in the target symptoms.
  • A new medication has been prescribed by another clinician, including herbal or compounded products.
  • You are pregnant, planning pregnancy, or breastfeeding — the regimen will need review.
  • You have a planned surgical or interventional procedure with prolonged immobilisation.
  • New or worsening breast tenderness, breakthrough bleeding, or migraine pattern.
  • Any post-menopausal bleeding.
  • You want to stop the medication — biio. will set up a step-down schedule if relevant.
  • You are due for routine hormone therapy review (typically every 6–12 months on stable therapy).
Talk to biio.1800 325 205

For questions about your dose, side effects, or anything in this guide.

In an emergency

For the tier-three emergencies above — rebound hypertension, collapse, overdose — call 000, not this line.

Guide version
1
Last reviewed
May 27, 2026
Prepared bybiio. prescribing team

This guide supports day-to-day use of micronised progesterone under the care of a biio. prescriber and does not replace individual clinical advice. If you are on combined hormone therapy, do not stop progesterone on its own while continuing oestrogen — the two are stopped together or under biio. guidance. If you are unsure about anything here, please contact biio. before making changes.