Progesterone: What It Does and How to Use It Safely

Progesterone is a hormone your body makes naturally. It helps regulate the menstrual cycle, supports early pregnancy, and balances estrogen in hormone therapy. People use prescription progesterone for missed periods, abnormal bleeding, fertility support, and as part of menopausal hormone therapy. There are also synthetic versions called progestins. Knowing the difference and how each form works matters for safety and results.

Common forms and when they’re used

Progesterone comes as oral capsules, vaginal gels or suppositories, and injections. Micronized oral progesterone (often called Prometrium) is a common natural form. Medroxyprogesterone acetate is a widely used progestin and behaves a bit different in the body. Vaginal forms deliver the hormone straight to the uterus and may cause fewer systemic side effects. Injections are used less often and usually under medical supervision. Your doctor will choose a form based on the condition being treated and your personal health history.

For fertility or luteal phase support, vaginal progesterone is common. For protecting the uterus during estrogen therapy in menopause, oral or cyclic progesterone schedules are typical. Dosing varies widely—what’s right for heavy bleeding is not the same as what’s used in fertility clinics. Always follow a prescriber's instructions.

Side effects, risks, and interactions

Side effects can include tiredness, breast tenderness, bloating, mood swings, and spotting. Some people notice increased hair growth or acne with certain progestins. Serious risks are rare but include blood clots, especially in smokers over 35 or people with clotting disorders. If you have liver disease, active cancer affected by hormones, or a history of stroke or deep vein thrombosis, talk to your doctor before taking progesterone.

Progesterone can interact with medications that change liver enzymes, like some antifungals, anticonvulsants, and certain antibiotics. That can make progesterone less effective or increase side effects. If you take other hormone medicines, blood thinners, or antidepressants, mention them when you get a prescription.

Practical safety tips: get a clear reason for prescribing, ask which form fits your goals, and confirm dose and schedule in writing. If you’re buying online, use a licensed pharmacy and keep the prescription. Watch for new or worsening symptoms and report them. For fertility, follow clinic protocols for timing and storage of vaginal suppositories or gels. For menopausal use, review benefits and risks yearly with your clinician.

Want specifics for your case? Talk to a healthcare pro who knows your history. Progesterone can help a lot when used correctly, but it’s not one-size-fits-all. A short conversation with your doctor can avoid common mistakes and get you the right form and dose.