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  • Writer's pictureGrace Health

5 Things That May Make Birth Control Less Effective

Updated: May 18, 2023

Are you relying on birth control to prevent pregnancy? While birth control is a highly effective method, several factors may reduce its efficacy. From missing pills to certain medications, it's important to understand what can impact the effectiveness of your birth control. In this blog post, we'll explore 5 things that may make birth control less effective and how to avoid them.

What factors make them less effective:

Taking other medications

Certain medications have been known to interfere with birth control and decrease its effectiveness. Some prescription medications that may make birth control less effective include:

  • enzyme-inducing seizure medications for epilepsy

  • some antiretroviral therapies (ART) for HIV

  • griseofulvin, an anti-fungal treatment

On the other hand, not all antibiotics cause problems with contraception. Most don’t but be on the lookout for an antibiotic called rifampin that reduces concentrations of estrogen in the blood. Always consult with your doctor before taking any contraceptive especially if you are on any form of medication.

Getting the timing wrong

While there are a variety of contraceptive options to choose from, most of them if not all, work on a specific schedule. This means that forgetting to take a dose or taking it late can mean a greater chance of pregnancy. For instance, if you’re on progestin-only pills, you must get your dose within the same 3-hour window every day for maximum effectiveness. Afraid you’ll forget? A good hack will be to set alarms to remind you to take your pills.

Not using barrier methods correctly

Examples of barrier methods are male or female condoms which are hormone-free and one of the most effective, cheapest and safest options available. As lucrative as they may sound, failing to use them in the right way could lead to pregnancy. When opening a condom package, be careful not to tear the condom, and hold the tip when putting it on to make sure air doesn’t get caught inside. Not sure how to use one? It helps to read instructions on the pack. Do some online research too!

Certain illnesses

Any acute illnesses or chronic conditions that prevent your body from fully absorbing your birth control pill can put you at higher risk for pregnancy, even if you use it perfectly. Another example is, if you vomit within two hours of taking your pill, your body most likely has not had enough time to absorb enough to be effective. In these cases, you should take your next active pill. It is advisable for women who have digestive disorders that cause consistent vomiting or bowel issues to seek alternative options for contraception.


There’s some evidence that suggests that obesity can reduce the effectiveness of some birth control methods, but it depends on the type. The studies argue that having a high body weight or BMI can affect the rate at which you metabolize your birth control pills.

Here are some birth control options that may be less effective for women with overweight or obesity:

  • combined oral contraceptives

  • the patch

  • emergency contraceptive pills

If you’re obese, you should talk to your doctor about whether or not birth control pills will be effective for you.

In summary

There are several 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 increase your chances of conception. Factors like medication, 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 in the right way that offers the benefits and level of protection that’s best for you.

Stay informed, stay in control Did you learn something new?

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