Though commonplace for many people, birth control is a complex process that requires careful follow-through. Keep reading to learn about simple things that can render birth control ineffective.

  • Many birth control options provide excellent protection against unwanted pregnancy with perfect use, but perfect use isn’t always possible.
  • Missing a dose, not abstaining during fertile windows, or not replacing your birth control method on time may reduce effectiveness.
  • Having overweight or obesity and taking some medications can also reduce effectiveness.

There are many birth control options available to reduce the chance of unplanned pregnancy. It’s common to choose a contraceptive method based on how well it’s supposed to work.

However, there are factors that can make several kinds of birth control less reliable.

Most statistics that explain effectiveness are based on perfect use, meaning the method is used exactly as directed. But it’s important to remember that most people aren’t perfect with their birth control.

A better figure may be typical use. Oral contraception, as an example, is more than 99 percent effective when used perfectly. That drops to 91 percent with typical use.

There are other factors besides not using the method perfectly that can reduce birth control effectiveness. Read on for some examples.

Some prescription medications may make birth control less effective. These include:

  • enzyme-inducing seizure medications for epilepsy
  • some antiretroviral therapies (ART) for HIV
  • griseofulvin, an antifungal treatment

A 1996 study reported that some anti-epileptic medications reduced oral contraception hormone levels and that many treating doctors were unaware of the connection.

Most data on ART and birth control pills remains unpublished, but the Centers for Disease Control and Prevention report some ART options may lower effectiveness of oral contraceptives.

Today, healthcare professionals should be aware of these drug interactions.

Don’t worry — most of the time, antibiotics cause no problems with contraception.

However, this isn’t always the case. One antibiotic called rifampin reduces concentrations of estrogen in the blood.

A study that reviewed more than 20 years of data from 1975 to 1998 found that birth control pills aren’t reliable for contraception when combined with rifampin.

Natural, integrative, and herbal remedies can reduce the efficacy of some birth control. St. John’s wort, for example, makes many drugs less effective, including the birth control pill.

There are different brands of birth control pills, but all work on a specific schedule. Forgetting to take a dose or taking it late can mean a greater chance of pregnancy.

As an example, if you’re on progestin-only pills, you must get your dose within the same 3-hour window every day for maximum effectiveness.

Birth control injections also contains progestin. If you get the birth control shot, you’ll require a new shot every 3 months.

Not getting a new shot from a doctor on time can reduce the effectiveness of this method.

Contraceptive patches and rings also have to be changed on a regular schedule. In addition, they have to stay in place in order to properly protect against pregnancy.

Common prophylactics can fail if they aren’t used the right way.

Take care when opening a condom package not to tear the condom, and hold the tip when putting it on to make sure air doesn’t get caught inside.

Follow instructions closely when using a diaphragm, as timing makes a difference. For example, if you put in a diaphragm longer than 2 hours before sex, the spermicide won’t work as well and you’ll get less protection.

Some people use fertility awareness as a method of contraception. This means taking precautions when you’re most likely to get pregnant according to your menstrual cycle.

This is considered one of the least effective methods of contraception, but it works for some people. Not abstaining when you’re fertile or not wearing a condom during sex on those days reduces the effectiveness of this method.

Vasectomy is one of the most effective ways to prevent pregnancy. But for the first 3 months after the procedure, couples should use an additional method of birth control.

Lactational amenorrhoea method (LAM) is a temporary birth control method used by those who have just had a baby. If you’re breastfeeding your baby and haven’t yet menstruated after having the baby, your body will temporarily stop ovulating.

However, for this to be most effective, you must breastfeed often.

There’s some evidence that obesity can reduce the effectiveness of some birth control methods, but it depends on the type.

A 2013 review of studies reported that the follow birth control options may be less effective for women with overweight or obesity:

  • combined oral contraceptives
  • the patch
  • emergency contraceptive pills

Some evidence suggests continuous use or a higher dose of oral contraceptives to increase efficacy in people with overweight or obesity.

Many birth control methods come with physical and emotional changes. If this happens to you, you can work with your doctor to find another solution that balances your birth control needs with the side effects.

Here are some reasons to see a doctor:

  • It’s hard to use your current method in the right way. For example, you may have trouble remembering to take your pill on time.
  • You have abnormal bleeding, bloating, migraines, or mood swings. Sometimes these are normal side effects of the birth control, but they can also signal serious underlying medical conditions.
  • You experience a low sex drive. Sometimes birth control pills cause reduced interest in sex. If this bothers you, you may want to change your method to something that doesn’t have this effect.

You may also want to see a doctor to change your birth control method because your personal preferences have changed. For example, you may want to consider an intrauterine device (IUD) so that you don’t have to remember to take a pill to prevent pregnancy.

Individuals and couples have a number of options to help with family planning and reduce the chance of unwanted pregnancy. Many of these methods are highly effective, but imperfect use of birth control can make them less so.

A number of medications, some lifestyle factors, and some medical conditions can also cause birth control to work less effectively.

Talk with your doctor to find a method you can use the in right way that offers the benefits and level of protection that’s best for you.