Oral contraceptive pills often contain progesterone and/or estrogen. Some variations include the progesterone-only pill. This particular pill is sometimes referred to as the "mini-pill" when used as birth control. The progesterone-only pill is used as an emergency contraceptive after unprotected sexual intercourse. Women may choose to use a progesterone-only birth control pill because it often has fewer side effects than pills containing estrogen as well, according to FamilyDoctor.org.
Bleeding
Bleeding between periods for several months after beginning progesterone-only pills is not uncommon. This typically goes away on its own, but FamilyDoctor.org recommends discussing heavy or persistent bleeding with a doctor. The National Institutes of Health (NIH) point out that some women may have irregular menstrual periods when they first begin this medication. This side effect should be temporary. Any woman who experiences long-lasting bleeding or a lack of menstrual periods should contact a doctor right away, as these are considered to be serious side effects.
Hunger
One common side effect of this type of pill is hunger. Feeling hungry frequently can lead to weight gain that goes away after the pill is discontinued. In addition to feeling hungry, some stomach upset is common but should diminish over time. Serious abdominal pain, states the NIH, is considered a cause for concern.
Other Side Effects
Breast tenderness is a common side effect that is not considered to be a health risk. Headaches, dizziness and acne are other potential side effects associated with progesterone-only pills. The NIH suggests some women may experience increased hair growth form the hormone in the pill.
