Side Effects

Drug information provided by: Merative, Micromedex®

Along with their needed effects, progestins used in high doses sometimes cause some unwanted effects such as blood clots, heart attacks, and strokes, or problems of the liver and eyes. Although these effects are rare, some of them can be very serious and cause death. It is not clear if these problems are due to the progestin. They may be caused by the disease or condition for which progestins are being used.

The following side effects may be caused by blood clots. Although not all of these side effects may occur, if they do occur they need immediate medical attention.

Get emergency help immediately if any of the following side effects occur:


  1. Symptoms of blood clotting problems, usually severe or sudden, such as:
  2. headache or migraine
  3. loss of or change in speech, coordination, or vision
  4. numbness of or pain in chest, arm, or leg
  5. unexplained shortness of breath

Check with your doctor as soon as possible if any of the following side effects occur:

More common

  1. Changes in vaginal bleeding (increased amounts of menstrual bleeding occurring at regular monthly periods, lighter vaginal bleeding between menstrual periods, heavier vaginal bleeding between regular monthly periods, or stopping of menstrual periods)
  2. symptoms of blood sugar problems (dry mouth, frequent urination, loss of appetite, or unusual thirst)

Less common

  1. Mental depression
  2. skin rash
  3. unexpected or increased flow of breast milk


For megestrol—During chronic treatment
  1. Backache
  2. dizziness
  3. filling or rounding out of the face
  4. irritability
  5. mental depression
  6. nausea or vomiting
  7. unusual decrease in sexual desire or ability in men
  8. unusual tiredness or weakness

Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

  1. Abdominal pain or cramping
  2. bloating or swelling of ankles or feet
  3. blood pressure increase (mild)
  4. dizziness
  5. drowsiness (progesterone only)
  6. headache (mild)
  7. mood changes
  8. nervousness
  9. pain or irritation at place of injection site
  10. swelling of face, ankles, or feet
  11. unusual or rapid weight gain

Less common

  1. Acne
  2. breast pain or tenderness
  3. brown spots on exposed skin, possibly long-lasting
  4. hot flashes
  5. loss or gain of body, facial, or scalp hair
  6. loss of sexual desire
  7. trouble in sleeping

Not all of the side effects listed above have been reported for each of these medicines, but they have been reported for at least one of them. All of the progestins are similar, so any of the above side effects may occur with any of these medicines.

After you stop using this medicine, your body may need time to adjust. The length of time this takes depends on the amount of medicine you were using and how long you used it. During this period of time check with your doctor if you notice the following side effect:

For megestrol

  1. Dizziness
  2. nausea or vomiting
  3. unusual tiredness or weakness

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.