Safety & honesty
What it feels like, what to watch for, and what we won't promise.
Progesterone has decades of use and a prescribing label that states its risks in full, boxed warning included. Here it is without the small print, so you know what the first capsules may feel like and when to stop.
Most reported, usually mild
- Drowsiness or dizziness after the capsule — expected — it is why the dose is taken at bedtime, and why you don't drive or operate machinery after it 1
- Breast tenderness — the effect most clearly tied to the capsule in the clinical trial 1
- Headache — common — and nearly as common on placebo 1
- Bloating or fluid retention — progesterone can hold some fluid; tell your clinician if you have a heart or kidney condition 1
- Low mood — reported more often than on placebo; worth telling your clinician early 1
- Vaginal discharge, nausea, joint aches — less often, and usually passing 1
Stop, and seek care straight away
- Bleeding you weren't expecting — any bleeding that doesn't fit the pattern your clinician set, or any bleeding after menopause, is checked — never watched 1 2
- Leg pain or swelling, chest pain, sudden breathlessness — a possible clot — treat it as an emergency 1
- Sudden weakness or numbness, trouble speaking, a severe headache — a possible stroke — treat it as an emergency 1
- Sudden loss of vision, double vision, a bulging eye or a new migraine — stop, and be examined before taking any more 1
- A new breast lump — examined promptly 1
Not prescribed if
- Undiagnosed abnormal vaginal bleeding 1
- Known, suspected or past breast cancer 1
- An active blood clot, or a history of clots in the legs or lungs 1
- A stroke or heart attack, now or in the past 1
- Liver disease 1
- Known or suspected pregnancy 1
- A peanut allergy, where the dispensed product contains peanut oil 1
Medicines that need care
- Estrogen from any prescriber — not a conflict — the reason. Tell the intake the form and the strength so the pattern is set with it in mind 2
- Ketoconazole, and other medicines that block the same liver enzyme — may raise progesterone levels; how much that matters in practice is unknown, so your clinician weighs it 1
- Anything else you take at night — the capsule's own drowsiness is enough to plan around — tell your clinician what else you take in the evening 1
- Other hormone products, including creams and pellets — listed one by one, so nothing doubles up
Monitoring
No blood test tells your clinician whether progesterone is protecting the lining. The signals are your bleeding pattern and your symptoms, reviewed periodically — the Menopause Society asks for individualized, periodic reassessment of the benefits and risks of continuing. 2
What it is for, and what it isn't
Progesterone alone is not the treatment of choice for hot flushes — estrogen is — and it isn't a sleeping pill. 2 The reference product is approved to protect the uterine lining alongside estrogen and to bring on a bleed when periods have stopped 1; taking it on its own for flushes or for sleep is off-label, with no long-term safety studies behind it 2. Your clinician tells you which reason you're being prescribed for.
If you stop
Nothing to taper. But if you take estrogen, don't stop the progesterone without stopping or discussing the estrogen — the lining loses its protection the moment the progesterone goes. 2 Any bleeding after stopping is reported.
Results vary. No outcome is guaranteed — your clinician will discuss what's realistic for you.