Dydrogesterone, sold under the brand name Duphaston among others, is a progestin medication which is used for a variety of indications, including threatened or recurrent miscarriage during pregnancy, dysfunctional bleeding, infertility due to luteal insufficiency, dysmenorrhea, endometriosis, secondary amenorrhea, irregular cycles, premenstrual syndrome, and as a component of menopausal hormone therapy. It is taken by mouth.

Side effects of dydrogesterone include menstrual irregularities, headache, nausea, breast tenderness, and others. Dydrogesterone is a progestin, or a synthetic progestogen, and hence is an agonist of the progesterone receptor, the biological target of progestogens like progesterone. The medication is an atypical progestogen and does not inhibit ovulation. It has weak antimineralocorticoid activity and no other important hormonal activity.

Dydrogesterone was developed in the 1950s and introduced for medical use in 1961. It is available widely throughout Europe, including in the United Kingdom, and is also marketed in Australia and elsewhere in the world. The medication was previously available in the United States, but it has been discontinued in this country.