Dydrogesterone

Dydrogesterone, a progesterone-like hormone you can swallow

Natural progesterone is poorly absorbed from a tablet, so a chemist reshaped the molecule. The result, dydrogesterone, has a structure close enough to progesterone to work on the same receptors in the womb lining, and it survives the trip through the gut. It does not behave like an androgen, an oestrogen or a cortisone-type hormone, and it does not suppress ovulation. That last point matters for anyone searching for it as a contraceptive: it is not one.

Which listing to choose

PockDose has two, and they are the same strength and form:

• Duphaston, 10mg tablets, listed for menstrual cycle disorders and endometriosis.
• Dydrogesterone tablets, 10mg, listed for endometriosis, infertility and premenstrual syndrome.

Both give you dydrogesterone in a 10mg tablet, so the decision comes down to the name you want on the pack and the price on each page.

What it is used for

Cycle problems come first: painful periods, irregular or absent periods, and heavy or erratic bleeding that traces back to low progesterone. Endometriosis follows, where the aim is to quiet the misplaced tissue. Premenstrual syndrome is the third main use, taken in the second half of the cycle. Beyond the cycle, dydrogesterone is paired with an oestrogen in hormone replacement so that the womb lining is not left unopposed, and it has a place in early pregnancy when miscarriage risk is tied to low progesterone or when a woman has had repeated miscarriages. The pattern is individual: some uses run only on set days of the cycle, others continuously.

Side effects, interactions and exclusions

Headache, migraine, nausea, breast tenderness and irregular bleeding or spotting are reported most often. Less often there are allergic skin reactions, mood changes, and liver effects shown by yellowing of the skin or eyes. Leg swelling with pain, or sudden chest pain and breathlessness, point to a clot.

Anyone with undiagnosed vaginal bleeding, severe liver disease, Dubin-Johnson or Rotor syndrome (rare inherited liver conditions) or a tumour that depends on progestogens should leave it out. Enzyme inducers such as phenytoin, phenobarbital, carbamazepine, rifampicin, efavirenz and St John's wort reduce its effect.