When to Use Backup Birth Control

Medically Reviewed by Traci C. Johnson, MD on June 11, 2022
5 min read

While you may hope you never need it, it’s important to know about backup birth control -- what your choices are, which type works best, and when to use it. Even the most careful couples can make a mistake.

You use backup birth control when you add a second, or even a third, type of contraception. This might be because your main method fails, you’re not consistent about using it, or you want to ensure you prevent pregnancy. It can include:

  • Condoms, which also protect against sexually transmitted infections (STIs), including HIV
  • Other easily reversible methods like a diaphragm, spermicide, or the sponge
  • Withdrawal, which isn’t highly effective on its own but which you can use with any other type of birth control
  • Emergency contraception like the morning-after pill

These are some of the reasons you might want to use a secondary method:

You want to be extra-sure to avoid pregnancy. No birth control method except abstinence is 100% effective. And human error reduces the effectiveness of many types. Using a backup method can give you peace of mind. Also, when you take a medication like the acne drug isotretinoin, which can cause birth defects in developing babies, your doctor may require you to use two types of contraception. You might combine an implant with a cervical cap, for example.

You’re afraid a condom might slip or tear. When used correctly, external condoms prevent pregnancy about 82% of the time. Internal condoms work about 79% of the time. But both types of condoms can break or slip. Backup birth control, like spermicide, can help avoid a pregnancy. So can emergency contraception after the fact. But you and your partner should never both use condoms at the same time during sex. That increases the chances one or both condoms will tear.

You don’t take the pill consistently.Birth control pills are almost 100% effective if you take them every day at about the same time. But if you forget them for a few days or don’t stick to a schedule, the odds of pregnancy increase to about 9 out of every 100 couples. If you miss one or more pills or start a pill pack late, use another form of birth control like a condom and foam until your next period. Or use emergency contraception.

You switch birth control methods midcycle. You need backup if you change the type of birth control pill you’re taking, or switch from one form of contraception to another (like from the pill to a hormonal IUD) more than 7 days after your period starts. Either don’t have sex or use a secondary method for the next 7 days. (You don’t need to do this if you get a copper IUD inserted, since it starts protecting you immediately.) If you switch to or from a vaginal ring or contraceptive skin patch, your doctor or nurse may tell you to use backup birth control in case you ovulate before the ring or patch starts working.

Your vaginal ring comes out. A vaginal ring is a hormonal form of birth control, but it can get displaced. You might not have put it in correctly, or it could slip out during sex. If it stays out for more than 3 hours, use another form of birth control for 7 days.

You use a diaphragm. Even if you use a diaphragm every time you have sex, you may not always insert it exactly right or use enough spermicide. Diaphragms also can slip, tear, or be taken out too soon, allowing sperm to reach your uterus. If you’ve gained or lost more than 15 pounds, they may no longer fit properly.

You use withdrawal, temperature, or calendar methods. Some people like these methods because they feel the most natural. But they don't work as well as other forms of birth control, failing 20% to 30% of the time. You and your partner also need some time to learn how to use these types of contraception correctly. Using more than one of these methods at a time – or adding another form of birth control, especially at fertile times of the month – will lower your chances of pregnancy.

You take medicine or supplements that interfere with your birth control. Sometimes, medications or supplements can interfere with your hormones and your birth control. Some medicines for HIV and epilepsy, and even certain antibiotics, lessen the effects of hormonal types of birth control like the pill, patch, implant, or ring. Some herbal supplements, like St John’s wort, saw palmetto, and chaste tree berry, may also make hormonal birth control less effective. Ask your doctor whether any new medication or supplement could mean you need a backup method.

You need emergency contraception. Use this form of backup birth control in the first few days after:

  • You had unprotected sex
  • You missed several birth control pills in a row
  • A condom slipped or broke during sex
  • You inserted your diaphragm, vaginal ring, or sponge incorrectly
  • You were the victim of a sexual assault

You can get several types of emergency contraceptives. Some contain hormones and some block the process of conception. Some, like ulipristal acetate (ella), require a prescription. You can buy others, like progestin-only pills (Next Choice, Plan B One-Step) over the counter. A copper IUD can also serve as emergency contraception (a doctor or nurse needs to insert it).

Emergency contraception is most effective when you use it within the first 3-5 days of having sex. It prevents pregnancy about 95% of the time if you take it in the first 24 hours. Don’t use emergency contraception as a regular form of birth control, since it’s not as reliable as things like the pill, IUD, or condoms.

How effective your backup birth control is depends on what types you use.

Some types of birth control work best when used together, like a condom and contraceptive foam. This method prevents pregnancy 97% of the time when used correctly. That’s more effective than either method by itself (82% for external condoms, 79% for internal ones, and 72% for spermicides).

You might want to double up if you use these types of birth control:

  • Withdrawal, with a failure rate of 18% to 19% for typical use
  • Fertility awareness-based methods (sometimes called the rhythm method): 24% failure rate
  • Cervical cap: 17%-23% failure rate
  • Sponge: 18%-24% failure rate
  • Diaphragm: 12% failure rate

For most hormonal contraceptives, like the shot, pill, patch, or vaginal ring, failure rates are 6% to 9%. IUDs and implants are long-lasting and work nearly 100% of the time.