Trimegestone, sold under the brand names Ondeva and Totelle among others, is a progestin medication which is used in menopausal hormone therapy and in the prevention of postmenopausal osteoporosis.

[4][2][3] It was also under development for use in birth control pills to prevent pregnancy, but ultimately was not marketed for this purpose.

[2] Side effects of trimegestone include headache, breast tenderness, nervousness, abdominal pain, bloating, muscle cramps, nausea, depression, and vaginal bleeding among others.

[16][10][3][7] Trimegestone is available both alone (as Ondeva) and in combination with estradiol (as Ginotex, Lovelle, Minique, Totelle), both of which are approved for the treatment of menopausal symptoms and prevention of postmenopausal osteoporosis.

[18] The most common side effects of trimegestone alone at dosages of 0.25 to 0.5 mg/day include breast tenderness (40.7–43.0%), abdominal pain (13.9–16.7%), headache (16.0–19.4%), nervousness (12.7–16.0%), bloating (10.3–16.0%), muscle cramps (12.3–13.9%), nausea (4.8–12.3%), and depression (3.0–3.1%).

[16][2] Unlike progesterone, trimegestone does not metabolize into neurosteroids and hence does not influence GABAA receptor signaling or produce sedative side effects.

[2][22] The 1β- and 6β-hydroxy metabolites of trimegestone are progestogens with considerable potency similarly and show little or no affinity to other steroid hormone receptors.

[9][21][25] The medication originated by Sanofi-Aventis in France, where promegestone was developed, and was first marketed by Wyeth in Sweden.

[14][6][27] Trimegestone is or has been marketed in Europe and Latin America, including in Argentina, Austria, Belgium, Brazil, Chile, Denmark, Finland, France, Italy, Lithuania, Mexico, Norway, Sweden, and Venezuela.

[15][14][6] The oral combination of trimegestone and ethinylestradiol was under development by Wyeth in the United States as a birth control pill to prevent pregnancy and the oral combination of trimegestone and conjugated estrogens was under development by Wyeth in the United States to treat menopausal syndrome and to prevent postmenopausal osteoporosis, but the development of both formulations was discontinued and they were never marketed.