Norethindrone acetate (brand names include Aygestin® and Gallifrey®) is a pill that contains the hormone progestin. Healthcare providers prescribe it to lighten or stop period bleeding. It works by keeping the lining of the uterus thin, so there is very little of it left to bleed during a period.

This medicine does not prevent pregnancy, so be sure to use birth control if you have sex.

• Follow your healthcare provider's instructions for dosing. The dose may change over time, but you will take pills every day.
• Take the pills at the same time every day. Setting a reminder on your phone can help you remember.
• If you forget to take a dose, take it as soon as you remember. If you miss more than two pills, call your healthcare provider. Missing doses can cause bleeding that can take a few days to stop.
• Do not stop taking the pills unless you talk to your healthcare provider first.

You:

• Have spotting or bleeding for more than a week after starting the medicine
• Stop bleeding, but then start to spot or bleed again
• Have symptoms of anemia (such as pale skin and lips, dizziness, tiredness, or a fast heartbeat) that don't start to get better within a few weeks or get worse
• Are gaining a lot of weight
• Develop acne or had acne but it's gotten worse

Why would someone want to take norethindrone acetate to stop periods? This can help someone who has:

• Very heavy or painful periods
• Anemia (low red blood cell counts) from heavy periods
• Bleeding between periods (including from some types of birth control)
• Prolonged periods (lasting more than two weeks)
• Trouble using pads and tampons because of physical or developmental challenges
• Endometriosis (tissue similar to the lining of the uterus but grows outside of the uterus)

Is it safe to stop periods? It's OK not to have monthly bleeding as long as your healthcare provider says that hormone medicines to stop periods are safe for you. However, if someone stops taking hormone medicines, their periods will start again.

Does norethindrone acetate cause side effects? Most people don't have any side effects. If they do have side effects, such as headaches or nausea (sick to the stomach), they usually go away within a few weeks. Less often, someone may have an increased appetite that can lead to weight gain, feel very moody, or have acne that gets worse.

What problems can happen? Norethindrone acetate is generally safe. But if it's taken for a long time, it may cause changes in cholesterol levels. It does not cause infertility (trouble getting pregnant) and does not cause cancer.