Progesterone (Micronised) — NZ Medication Guide
📋 Reviewed by a Registered Pharmacist NZ — This information is for general educational purposes only and does not replace professional medical advice. Always consult your doctor or pharmacist before starting, stopping, or changing any medication.
What is Progesterone (Micronised)?
Micronised progesterone is a bioidentical progesterone used as part of menopausal hormone replacement therapy to protect the uterine lining. This medication is funded by Pharmac as part of HRT.
What is Progesterone (Micronised) Used For?
Micronised progesterone (Utrogestan®) is used as the progestogen component of menopausal HRT in women with an intact uterus — protecting the endometrium from oestrogen-induced hyperplasia and cancer. It is also used in early pregnancy to support the luteal phase.
How Does Progesterone (Micronised) Work?
Progesterone binds to progesterone receptors in the uterine endometrium, converting the proliferative endometrium (stimulated by oestrogen) into a secretory endometrium that is less responsive to oestrogen — preventing endometrial hyperplasia and cancer.
How to Take Progesterone (Micronised)
For HRT: taken orally 200 mg/night for 12–14 days per month (cyclical HRT) or 100 mg/night continuously (continuous combined HRT). Utrogestan® is best taken at bedtime as it has a sedative effect. Vaginal administration (same capsule) provides local endometrial protection with fewer systemic side effects.
Common Side Effects of Progesterone (Micronised)
- Drowsiness and sedation (particularly with oral use — take at bedtime)
- Breast tenderness
- Headache
- Dizziness
- Mood changes
Serious Side Effects — Seek Medical Attention
Contact your doctor or call 111 immediately if you experience any of the following:
- Breast cancer (combined HRT with synthetic progestogens carries higher breast cancer risk than natural progesterone — micronised progesterone appears to have lower risk than synthetic progestogens based on observational data)
- Thromboembolism (lower risk than synthetic progestogens — largely neutral)
Drug Interactions
Progesterone (Micronised) may interact with other medicines. Always inform your doctor and pharmacist of all medications you are taking. Key interactions include:
- CNS depressants (additive sedation with oral micronised progesterone)
- Enzyme inducers (carbamazepine, rifampicin — reduce progesterone levels)
- Ciclosporin (increased levels)
New Zealand Prescribing Information
Micronised progesterone (Utrogestan® 100 mg and 200 mg capsules) is funded by Pharmac. It is increasingly preferred over synthetic progestogens in HRT due to its more favourable side effect profile, neutral cardiovascular effects, and potentially lower breast cancer risk based on observational studies (though RCT evidence is limited). Its sedative property at the oral dose makes bedtime dosing advantageous.
Frequently Asked Questions
Is micronised progesterone better than other progestogens in HRT?
Observational studies (particularly the large French E3N cohort) suggest micronised progesterone (and dydrogesterone) have a lower risk of breast cancer than synthetic progestogens. However, this is based on observational evidence, not randomised trials. It is currently the preferred progestogen option at many NZ menopause clinics.
Can I take Utrogestan® vaginally?
Yes — Utrogestan® capsules can be inserted vaginally. Vaginal administration delivers progesterone directly to the uterus with lower blood levels and fewer systemic side effects (less sedation, mood effects). This route is commonly used in NZ for women who find the sedative effect of oral Utrogestan® troublesome.
⚠️ Disclaimer: This page is for educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your doctor or a qualified health provider. In New Zealand, medication availability and funding may vary — check with Pharmac or your pharmacist for current information.
Reviewed by a Registered Pharmacist NZ
References & Further Information
The following New Zealand and international resources were used to inform this page: