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Birth Control Pills

How Soon Do Birth Control Pills Work?

When taken as directed, birth control pills are usually effective the first month you begin taking them. To be safe, some doctors recommend the use of another form of birth control, such as condoms and foam, during the first month. After the first month, you can just rely on the pill for birth control.

What If I Forget to Take a Birth Control Pill?

If you forget to take a birth control pill, take it as soon as you remember. If you don't remember until the next day, go ahead and take two pills that day. If you forget to take your pills for two days, take two pills the day you remember and two pills the next day. You will then be back on schedule. If you miss more than two pills, call your doctor. You may be told to take one pill daily until Sunday then start a new pill pack or to discard the rest of the pill pack and start over with a new pack that same day.

Any time you forget to take a pill, you must use another form of birth control until you finish the pill pack. When you forget to take a pill, you increase the chance of releasing an egg from your ovary. If you miss your period and have forgotten to take one or more active pills, get a pregnancy test. If you miss two periods even though you have taken all your pills on schedule, you should get a pregnancy test. 

With some pills you may not have a period. Talk with your doctor before you start taking your pills about what to expect, and then follow your doctor's instructions about what to do if you don't have a period. 

It is very important to take the mini pills (progestin only) at the exact same time each day. If you miss a pill or are more than three hours late for a pill you should take the pill as soon as you remember and use a backup method (such as a condom or spermicide) for the next 48 hours.

Are There Side Effects of Birth Control Pills?

Yes, there are side effects of birth control pills, although the majority are not serious. Side effects include:

  • Nausea
  • Weight gain
  • Sore or swollen breasts
  • Small amounts of blood, or spotting, between periods
  • Lighter periods
  • Mood changes

The following side effects, easily remembered by the word "ACHES," are less common but more serious. If you experience any of these, contact your doctor immediately. If you cannot reach your doctor, go to an emergency room or urgent care center for evaluation. These symptoms may indicate a serious disorder, such as liver disease, gallbladder disease, stroke, blood clots, high blood pressure, or heart disease. They include:

  • Abdominal pain (stomach pain)
  • Chest pain
  • Headaches (severe)
  • Eye problems (blurred vision)
  • Swelling or aching in the legs and thighs

WebMD Medical Reference

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