Does the effectiveness of emergency contraception pills vary based on the amount of times I've had unprotected sex?

Dear Reader, 

The short and simple answers to your questions are no and yes, respectively. As long as the emergency contraception (EC) pill is taken within the timeframe specified for each brand, its effectiveness won’t be altered. When used as directed, the EC pill is designed to prevent pregnancy before it happens regardless of how many times you’ve had sex.  

What is the emergency contraceptive (EC) pill? 

The emergency contraceptive pill is a medication that prevents pregnancy. Unlike birth control options, which are taken or used regularly, the emergency contraceptive pill is taken after sex. However, this form of birth control is used after sex. Though some call it the “morning after pill,” you can take most brands up to 72 hours after sex. In fact, it works best when taken as soon as possible, whether it’s morning, afternoon, or night!  

How does the EC pill work? 

In a nutshell (or rather, an eggshell), the EC pill stops or delays the release of an egg from the ovaries. This gives time for the sperm in the body to die and prevents the egg from being fertilized. Because the EC pill affects the egg release, the number of times you’ve had sex in a short period of time likely won’t affect how well it works.  

For more information about EC in general, consider checking out Where can I find basic information about emergency contraception? 

What can reduce the efficacy of the EC pill?? 

 The EC pill is most effective when it’s used as directed and within the timeframe specific to the brand you’re using. These directions will indicate when to take it and if there are reasons you shouldn’t use it. While the EC pill is a useful tool for many people, there are some factors that may limit its effectiveness. Some of these include:  

• Weight: The EC pill may not be as effective for people weighing over 195 pounds. In these cases, a health care provider may recommend a different form of emergency contraception, such as an intrauterine device (IUD).  
• Medication interactions: Some medications may cause harmful or unintended reactions when taken with the EC pill.  

What doesn’t the pill do? 

The EC pill can be a helpful option in preventing unwanted pregnancy. However, many people have misconceptions about what it does and doesn’t do. It’s worth noting that there are some limitations in how it can be used. The EC pill does not: 

• End pregnancy. The EC pill prevents pregnancy before it occurs. It does not cause abortion or miscarriage once a person is already pregnant.  
• Function as routine or long-lasting birth control. The EC pill cannot be used as proactive contraception and does not prevent pregnancy long-term.  
• Protect against sexually transmitted infections (STIs). Barrier methods, specifically condoms, are currently the only form of contraception that can protect against STIs.  

If you’d like to explore other forms of birth control, the Birth Control Basics fact sheet provides more information on what options are available.   

Here’s to a good night and a happy morning after!