Anti-abortion proponents claim that it’s possible to reverse emergency contraception, such as Plan B, or medical abortion — but “abortion pill reversal” is unproven and dangerous.

“Abortion reversals” are sometimes offered by crisis pregnancy centers, which are anti-abortion organizations that look like legitimate healthcare centers.

Despite claims to the contrary, there are no treatments proven to reverse abortions or emergency contraception.

Many states have passed laws requiring abortion providers to tell people that abortion reversal is possible if they change their minds. But “abortion pill reversal,” as it’s often called, is an unproven and unsafe procedure.

Currently, the Food and Drug Administration (FDA) hasn’t approved abortion reversal treatments, and the American College of Obstetricians and Gynecologists (ACOG) explicitly warns against these treatments because they haven’t been proven to be effective or safe.

It’s important to know that Plan B and other emergency contraceptive pills aren’t the same as abortion medication, though they’re often referred to as abortion pills by anti-abortion proponents.

There’s no controlled, clinical study that proves “abortion reversal” is possible.

If you have a medical abortion, you’ll likely take two kinds of pills: first mifepristone, and then misoprostol.

Mifepristone stops a pregnancy from growing by temporarily blocking your body from making or using progesterone properly, while misoprostol causes your uterus to shed its lining.

‘Reversal’ with progesterone

In 2012, a San Diego physician named George Delgado gave progesterone to a pregnant person who had taken mifepristone but not misoprostol.

According to Delgado, the pregnancy continued successfully. Delgado repeated this process with other people.

Delgado then co-authored a report detailing the experiences of six pregnant people who received progesterone injections after taking mifepristone. Only four people carried their pregnancies to term.

In 2018, Delgado authored a larger study, observing 547 people who were given progesterone after using mifepristone. About 48% of people who received progesterone continued their pregnancies.

But as ACOG highlighted, there was no control group, no ethical review committee approval, and no reported safety outcomes. ACOG also noted that data was under-reported in the study.

It’s worth noting that up to 46% of pregnancies will continue if you take mifepristone but not misoprostol.

A 2015 review found no evidence that taking progesterone after mifepristone would increase the likelihood of your pregnancy continuing compared with taking mifepristone alone.

But, taking mifepristone without misoprostol can lead to severe bleeding, which is dangerous.

‘Reversal’ risks

A 2020 study was the first of its kind to evaluate medication abortion reversal in a controlled setting, but it ended early because of safety concerns for its participants.

The authors intended to enroll 40 people but only enrolled 12. All participants ingested mifepristone and were then either given a placebo or progesterone.

Six participants received a placebo and the other six received progesterone as per the previous studies. All participants were planning to have a surgical abortion at a later stage.

Two people — one who received progesterone, one in the placebo group — voluntarily discontinued their pregnancies after three days due to nausea, vomiting, and bleeding.

Six people — four who received progesterone, two in the placebo group — continued their pregnancies for 2 weeks, until their surgical abortion.

Four pregnancies — one from a person who received progesterone, three in the control group — ended.

Three people — one who received progesterone, two in the placebo group — had to be taken to hospital by ambulance due to severe bleeding. This led the authors to end the study early.

These limited results couldn’t verify if “abortion reversal” was possible, but the authors noted that using mifepristone without misoprostol could cause significant bleeding.

There are no studies on reversing emergency contraceptive or “morning after” pills. It’s worth noting that emergency contraception pills and IUDs do not contain mifepristone or misoprostol.

Emergency contraception can only prevent pregnancy from occurring — it’s unable to end an existing pregnancy.

Although “abortion reversal” treatments are unproven and possibly dangerous, the myth has persisted and gained traction in recent years.

Several states have laws that require healthcare professionals to give people scientifically unsound “counseling” before an abortion — and some require them to tell people that “abortion reversal” is possible.

At the same time, healthcare professionals aren’t allowed to tell people about the lack of scientific evidence supporting “reversal” or about the associated dangers.

The concept of “abortion reversal” is pushed by the Abortion Pill Rescue Network. The Abortion Pill Rescue Network is backed by Heartbeat International, an anti-abortion group that supports a large network of crisis pregnancy centers.

Crisis pregnancy centers are designed to discourage abortion and contraception use. They look like legitimate health clinics, but they’re not regulated or licensed.

If you look up abortions, abortion clinic, or “abortion reversal,” you’re likely to come across websites claiming that abortion is unsafe or reversible.

Some of these websites may look like they’re run by legitimate health clinics. But, many are crisis pregnancy centers funded by anti-abortion organizations.

In the only controlled study on “abortion reversal,” 3 of the 12 participants were hospitalized with severe bleeding after taking mifepristone without misoprostol. This happened to one participant in the study group and one in the control group.

The other major risk is that it won’t work. As mentioned, there’s no evidence that this potentially dangerous method actually works.

Even Delgado’s own studies — which had no control groups and weren’t overseen by an ethics committee — found that the “abortion reversal” procedure only appeared to work in 48%66% of cases.

Even so, those studies were criticized for under-reporting data and not covering safety and side effects.

It’s possible that you won’t experience any side effects after taking emergency contraception. A lack of side effects doesn’t mean it’s not working.

Possible side effects can include:

  • abdominal pain or cramps
  • breast or chest tenderness
  • dizziness
  • headaches
  • nausea
  • vomiting

Your next menstrual period might be heavier, lighter, earlier, or later than usual. These changes are temporary.

Levonorgestrel emergency contraceptive pills, such Plan B One-Step, can reduce the chance of pregnancy by 75%–89% if taken within 72 hours (3 days) of sex.

Levonorgestrel may be less effective if your body mass index (BMI) is 26 or higher. It’s still safe for you to use.

Ella (ulipristal acetate) can lower your chances of becoming pregnant by 85% if taken within 5 days of sex. It’s more effective than levonorgestrel pills if you have a BMI of 26 or higher.

Mifepristone on its own doesn’t always cause abortion. Up to half of people who take mifepristone but not misoprostol continue their pregnancies. If you carry to term, it’s unlikely to cause birth defects.

But, taking mifepristone but not misoprostol can cause severe bleeding several days later. If you’re bleeding significantly, consider staying with a friend or having a loved one check in on you frequently so that they can help you get to a hospital if needed.

If you want to have an abortion, you must take misoprostol 24–48 hours after taking mifepristone.

Although medical abortion is more effective when mifepristone and misoprostol are used together, misoprostol alone usually works if used in the early stages of pregnancy.

A 2019 study concluded that misoprostol-only abortions are safe and effective in the first 12 weeks of pregnancy. The typical dose is 800 micrograms (mcg) or four tablets of 200 mcg each.

If you don’t take all tablets, there’s a chance — though a very low chance — that your pregnancy will continue.

Taking fewer doses than prescribed can be dangerous, as the contents of your uterus may become toxic to your body. You may require a surgical abortion at a later stage.

Consult with a healthcare professional as soon as possible.

If you need immediate help, you can contact:

For compassionate and nonjudgmental post-abortion counseling:

You may also find help through:

Healthline has compiled numerous articles about abortion and emergency contraception, including:

Sian Ferguson is a freelance health and cannabis writer based in Cape Town, South Africa. She’s passionate about empowering readers to take care of their mental and physical health through science-based, empathetically delivered information.