You may have spotting or bleeding between periods. This is called breakthrough bleeding and is not harmful. If it persists for more than 3 months, contact your clinician. Some women using the Pill experience unpleasant side effects that are not dangerous and are unlikely to damage their health, such as breast tenderness, mild nausea, or minor weight changes, often due to fluid retention. These are the most common and usually subside after the body adjusts to the change in hormone levels.
Many women have no side effects at all.
If side effects become intolerable, consult your clinician. As with other medications, there are certain risks but serious problems are relatively rare. The most serious risk to the Pill is abnormal blood clotting. Cigarette smoking increases the risk of serious adverse effects on the heart and blood vessels. Women who use the pill should not smoke.