May 21, 2021

What You Need To Know About The Morning-After Pill

The morning-after pill is a common form of contraception, but how does it work? How is it safe to use? How often should women use it? The “morning-after pill” is one of many types of birth control, with its own side effects and risks. However, it should not be your primary form of birth control. Here’s what you need to know about this pill. 

Morning-After Pill: A Popular Plan B

What even is the “morning after pill”? This form of contraception is exactly what the popular name brand suggests—a plan B when you need it. The keyword here, however, is need. The morning-after pill is an emergency contraceptive and should not be your regular method of birth control

Suppose you’ve had unprotected sex, or your primary method of birth control method has failed. In that case, emergency contraception is up to 87% effective if taken as directed and within 72 hours after you’ve had sex. Morning-after pills contain either levonorgestrel (Plan B One-Step, Aftera, others) or ulipristal acetate (ella).

How Does The Morning-After Pill Work?

To understand how this method of birth control works, let’s go back to the basics of the female reproductive system. When you have sex, your chances of getting pregnant are greatest in the two days leading up to and including ovulation, when your body releases an egg. An egg lives for 24 hours, and sperm can live for up to three to five days. Therefore conception can occur several days after sex. 

The morning-after pill works by delaying the increase in the hormone that starts ovulation. By delaying or stopping the egg from being released, the sperm can’t reach the egg, preventing you from getting pregnant. Therefore, you need to take the morning-after pill before you have that hormone surge. 

The pill’s effectiveness decreases the closer you take it to your ovulation period, and it is not effective if you take the pill after fertilization. This is why this birth control pill is notoriously named after the optimal time to take it—the morning after you have sex. 

Birth Control Side Effects

Here are some common side effects of this birth control, which typically last only a few days:

  • Nausea or vomiting
  • Dizziness
  • Fatigue
  • Headache
  • Breast tenderness
  • Bleeding between periods or heavier menstrual bleeding
  • Lower abdominal pain or cramps

While these side effects are usually nothing to worry about, if you vomit within two hours after taking the pill, ask your health care provider if you should take another dose. In addition, you shouldn’t have sex until you start another method of birth control. The morning-after pill doesn’t offer lasting protection from pregnancy. If you have unprotected sex in the days and weeks after taking the morning-after pill, you’re still at risk of becoming pregnant. 

Woman not feeling well, sitting on couch clutching a heating pad towards her pelvic area.

Side effects are completely normal after you take the morning-after pill, but contact your doctor for any concerning or severe symptoms.

Be sure to begin using or resume use of your primary method of birth control. After taking the morning-after pill, you should use a barrier method of contraception, such as condoms, for the remainder of your cycle. Keep in mind that the morning-after pill might delay your next period. However, if your period is more than 21 days late, it’s best to take a pregnancy test.


One of the most common myths about this one-time birth control pill is that it is similar to having an abortion. This is simply not true. The morning-after pill is not the same as mifepristone (Mifeprex), also known as RU-486, the abortion pill. This drug terminates an established pregnancy, one in which the fertilized egg has attached to the uterine wall and has begun to develop. 

If you are already pregnant, morning-after pills cannot work. These pills work primarily by delaying or preventing ovulation so that fertilization does not occur in the first place. By definition, the morning-after pill cannot be deemed an abortifacient.

We’ve Got You Covered: Birth Control in Miami

Dr. Fox’s years of experience in the field has allowed her to construct a devoted group of professionals who will go the extra mile to ensure their patients are completely satisfied after each appointment. If you’re unsure which form of birth control is right for you, Dr. Susan Fox is here to help. Whether you’re looking for an IUD, a daily pill, or an arm implant, our team is knowledgeable on all types of birth control and their side effects. Give us a call and visit our Miami office today!

Birth Control, Blog, Dr. Susan Fox, OBGYN Miami, Pregnancy , ,
About OBGYN Miami