Common side effects of progestin include abdominal pain, cramping, mild headache, mood changes or drowsiness, according to Mayo Clinic. Additional side effects include swelling of the feet or ankles, weight gain, dizziness, nervousness and a mild increase in blood pressure.
Less common side effects that normally don't require medical attention include breast tenderness, brown spots on the skin, acne and hot flashes, notes Mayo Clinic. Patients may also experience difficulty sleeping, a loss of sexual desire, and changes in scalp or body hair. Patients should contact a doctor if these side effects are bothersome or persistent. In large doses, progestin occasionally causes blood clots, strokes, eye problems, liver problems and heart attacks. In the event of a blood clotting issue, which requires emergency medical attention, the patient may experience vision changes, coordination problems, headaches, shortness of breath, or numbness in the chest or limbs.
Patients should consult a doctor as soon as possible if certain common side effects occur, confirms Mayo Clinic. These include changes in vaginal bleeding, such as bleeding between menstrual periods or increased bleeding during menstrual periods, and symptoms of low blood sugar, such as frequent urination, loss of appetite and dry mouth. Less common symptoms include skin rash, depression and an increase in breast milk.