You'll need a prescription for the minipill from your health care provider. Minipills usually come in packs of 28 active pills. This means that all the pills contain progestin. There are no inactive pills without hormones.

As long as you aren't pregnant, you can start taking the minipill anytime — ideally on the first day of your menstrual period.

You might be able to skip the recommended two days of avoiding sex or using backup birth control, such as a condom, if you start taking the minipill:

• During the first five days of your period.
• Between six weeks and six months after giving birth if you are fully breastfeeding and haven't had a period.
• Within the first 21 days after giving birth if you're not breastfeeding.
• The day after you stop using another hormonal method of contraception.
• Right away after a pregnancy loss or abortion.

If you start taking the minipill more than five days after the start of a period, you may need to avoid sex or use a backup method of birth control for the first two days you take the minipill.

If you're switching from a combination birth control pill to the minipill, start taking the minipill the day after you take your last active combination birth control pill.

Talk with your provider so that you know when you need to avoid sex or use a backup method of birth control when starting and using the minipill.

The minipill norethindrone is an oral contraceptive that contains the hormone progestin. Oral contraceptives are medicines used to prevent pregnancy. These medicines also are called birth control pills.

Unlike combination birth control pills, the minipill — also known as the progestin-only pill — doesn't have any estrogen in it.

The minipill thickens cervical mucus and thins the lining of the uterus. These prevent sperm from reaching the egg and a fertilized egg from implanting in the womb. The minipill may keep you from ovulating. This means that the pill keeps your ovaries from releasing an egg. However, about half the people using the minipill still ovulate.

To be effective in preventing pregnancy, you must take the minipill every day at the same time.

Pregnancy

With typical use, as many as 9 out of 100 people who use the minipill will get pregnant during the first year of use. With perfect use as directed, the pregnancy rate is less than 1 in 100 people every year. This rate is close to that of other birth control methods that use hormones.

If you get pregnant while taking the minipill, there appears to be a slightly higher chance that the fertilized egg will implant outside the uterus, usually in a fallopian tube. This is called an ectopic pregnancy. The fallopian tubes carry eggs from the ovaries to the uterus.

There doesn't seem to be an increased risk of birth defects in babies born to people taking the minipill while pregnant. But you should stop taking the minipill as soon as you find out you're pregnant.

Sexually transmitted infections

The minipill won't protect you from sexually transmitted infections. To help protect against these infections, practice safer sex.

Side effects

Side effects of the minipill might include:

• Irregular menstrual bleeding and spotting.
• Acne.
• Breast tenderness.
• Decreased sex drive, also called libido.
• Depression.
• Headaches.
• Nausea.
• Ovarian cysts.

While taking the minipill, you may have less bleeding during periods or you may not have any bleeding at all.

To use the minipill:

• Talk to your health care provider about a starting date. Make sure you have a backup method of birth control available if needed.
• Choose a routine time to take the pill. It's important to take the minipill at the same time every day. If you take the minipill more than three hours later than usual, avoid sex or use a backup method of birth control for at least two days.
• Know what to do if you miss pills. If you miss taking a minipill by more than three hours after your routine time, take the missed pill as soon as you remember, even if it means taking two pills in one day. Avoid sex or use a backup method of birth control for the next two days. If you've had unprotected sex, talk to your health care provider about the type of emergency contraception you should use.
• Don't take breaks between pill packs. Always have your next pack ready before you finish your current pack. Unlike combination birth control pills, minipill packs don't contain a week of inactive pills.
• Know what to do when you're sick. If you have vomiting or severe diarrhea while using the minipill, the progestin might not be absorbed by your body. Avoid sex or use a backup method of birth control until two days after the vomiting and diarrhea stop. If you throw up within three hours of taking a minipill, take another pill as soon as possible.
• Tell your health care provider about all medicines you take. Some medicines may make the minipill less effective. For example, you may need to use a backup method of birth control when taking certain antibiotics.

If your period is heavier than expected or lasts for more than eight days, talk to your health care provider. Also contact your provider if you have any concerns or if you'd like to change to another method of birth control.

Your health care provider can talk with you about birth control options to decide if minipills are right for you.

The minipill is a method of birth control that's easy to reverse. And your fertility is likely to return quickly. You can get pregnant almost right away after you stop taking the minipill.

Besides preventing pregnancy, the minipill may reduce or stop heavy or painful periods. The minipill also may help treat a type of skin irritation called estrogen dermatitis that seems to be related to the menstrual cycle.

You might consider the minipill if:

• You've given birth or are breastfeeding. The minipill is safe to start any time during breastfeeding. It does not affect the amount of milk produced. You can begin using the minipill right away after giving birth, even if you're not breastfeeding.
• You have certain health problems. If you have a history of blood clots in the legs or the lungs, or if you have an increased risk of those conditions, your provider might advise that you take the minipill. The minipill also might be a good choice if you have high blood pressure or heart problems.
• You're concerned about taking estrogen. Some women choose the minipill because of possible side effects of birth control pills containing estrogen.

But the minipill isn't the best choice for everyone. Your health care provider may not advise you to take the minipill if you:

• Have past or present breast cancer.
• Have certain liver diseases.
• Have unexplained uterine bleeding.
• Take certain medicines for tuberculosis or HIV/AIDS or to control seizures.

If you'll have trouble taking the pill at the same time every day due to a changing work schedule or other factors, the minipill may not be the best birth control choice.