Progesterone is a natural hormone that controls the second half of your menstrual cycle and helps support early pregnancy. If you’ve ever heard about "luteal phase support" or hormone replacement, progesterone is often the reason. This page gives straight facts—what it does, common uses, how people take it, likely side effects, and simple tips to stay safe.
Why progesterone matters
After ovulation your body makes progesterone to prepare the uterus for a fertilized egg. If levels stay high, pregnancy can continue. If they fall, your period starts. Doctors measure progesterone with a blood test about a week after ovulation to confirm ovulation happened. Clinically, progesterone or synthetic progestins are used for: preventing endometrial overgrowth during estrogen therapy, supporting early pregnancy in some fertility treatments, treating irregular bleeding, and as part of some birth control methods.
Common forms and how people take it
Progesterone comes in several forms. Each works a bit differently and your doctor will recommend one based on the goal:
- Oral capsules (micronized progesterone): taken by mouth, often nightly for luteal support or HRT.
- Vaginal gels, suppositories, or capsules: used for fertility support because they deliver hormone directly to the uterus area.
- Intramuscular injections (often progesterone in oil): used in some fertility clinics for stronger, steady levels.
- Synthetic progestins (like medroxyprogesterone): found in many birth control pills and some HRT prescriptions; they act like progesterone but aren’t identical.
Typical dosing varies a lot by reason for use. For example, vaginal doses for fertility are usually small and frequent, while oral HRT doses differ. Follow your prescriber’s instructions—don’t guess the dose.
Possible side effects and safety notes
Many people tolerate progesterone well, but side effects can include tiredness, mood changes, breast tenderness, bloating, headaches, and spotting. If you feel severe depression, chest pain, shortness of breath, or signs of a blood clot, seek medical care right away. Progesterone interacts with some medications (CYP3A4 inducers can lower levels). Tell your doctor about all medicines and supplements you take.
Practical tips
- Take it the way your prescriber tells you—timing matters for some uses. Avoid stopping suddenly unless told to do so.
- If you’re on estrogen therapy, progesterone protects the uterine lining—don’t skip it unless directed.
- If you’re trying to conceive or are pregnant, discuss the exact form and dose; clinics often prefer vaginal or injected forms for fertility support.
- Keep a symptom diary for mood, bleeding, and side effects—this helps your clinician adjust treatment.
Want specific advice? Talk with your healthcare provider. They’ll match form and dose to your situation and monitor any side effects or interactions.
Estrogen and progesterone are key players in the regulation of ovulation and menstrual cycles, orchestrating complex processes that ensure reproductive health. Estrogen promotes the growth of the uterine lining and influences ovulation, while progesterone stabilizes this lining and prepares the body for pregnancy. Understanding the symbiotic relationship between these hormones offers insights into managing menstrual health and addressing related disorders.
