What Happens If the Abortion Pill Doesn’t Work?

When medication abortion fails, the pregnancy either continues with a live embryo or ends incompletely, leaving tissue behind in the uterus. Either scenario requires medical follow-up, and in most cases, a procedure or additional medication finishes what the pills did not. The overall failure rate is low, roughly 2 to 5 percent when mifepristone and misoprostol are used together, but the consequences of an unrecognized failure can be serious enough that knowing what to watch for matters.

How Often Medication Abortion Fails

The standard two-drug regimen, mifepristone followed by misoprostol, succeeds about 95 to 98 percent of the time when used within the approved gestational window. A large prospective study of over 1,500 women using mifepristone with buccal misoprostol through 59 days of gestation found a success rate of 98.3 percent, with slightly lower effectiveness at later gestational ages compared to earlier ones.¹ When misoprostol is used alone, without mifepristone, success drops considerably. A systematic review of misoprostol-only regimens found that about 22 percent of women needed surgical evacuation, and roughly 7 percent had an ongoing pregnancy.²

Real-world numbers can fall below clinical trial results. One teaching hospital reported success rates dropping from 87 percent to 79 percent over time, largely because of inconsistent staff experience and unclear criteria for defining failure on ultrasound.³ In telemedicine-based services, where patients self-manage at home, around 96.4 percent reported ending their pregnancy without surgical intervention, with about 1 percent experiencing a serious adverse event.⁴ So the gap between a controlled study and everyday practice is real, but the overall picture is one of high effectiveness with a small but meaningful tail of failures.

The Two Kinds of Failure

Not all failures look the same. There are two distinct outcomes when medication abortion does not fully work, and they carry different risks and require different responses.

The first is a continuing pregnancy, where the embryo or fetus remains alive and developing. This is the rarer but more urgent scenario, because the window for a safe follow-up procedure narrows as weeks pass. In a survey of women who had medication abortions, about 2.2 percent reported a continuing live pregnancy as a complication.⁵

The second is an incomplete abortion, where the pregnancy has ended but tissue remains in the uterus. Retained tissue frequently causes irregular or continuous vaginal bleeding, lower abdominal pain, and sometimes infection-related discharge.⁶ Left untreated, retained tissue can lead to late complications including intrauterine adhesions and reduced fertility. The distinction between continuing pregnancy and incomplete abortion usually requires an ultrasound, since symptoms alone may not tell the full story.

Warning Signs That Something Is Wrong

After taking both medications, heavy cramping and bleeding are expected and are actually signs the pills are working. The concern is when symptoms are either too extreme or suspiciously absent. Research has identified several warning signs worth taking seriously: bleeding heavy enough to soak more than two pads per hour for over two hours, pain that does not respond to pain relievers and prevents normal activity, fever above 38°C lasting more than 24 hours, and foul-smelling yellow or green vaginal discharge.⁷

On the opposite end, minimal bleeding and cramping after taking misoprostol can signal that the medication did not induce the expected process. Some people assume light symptoms mean the abortion was easy, when they may actually mean it did not happen. Pregnancy symptoms that persist, like ongoing nausea and breast tenderness weeks after taking the pills, are another red flag. Neither set of symptoms provides a definitive answer on its own, which is why follow-up verification exists.

How to Confirm the Abortion Worked

Standard home pregnancy tests are not very useful in the days after a medication abortion because pregnancy hormone levels take time to drop, and a positive test does not distinguish between lingering hormones and an ongoing pregnancy. Instead, clinicians have moved toward low-sensitivity urine pregnancy tests designed to detect only higher hormone levels. These tests are tuned to pick up the sustained hormone levels of an ongoing pregnancy while ignoring the declining levels that naturally follow a completed abortion.

A systematic review of these low-sensitivity tests found that their ability to detect ongoing pregnancy ranged from 67 to 100 percent across different studies, with randomized trials showing no significant difference in detecting ongoing pregnancies between the test-at-home strategy and routine in-person follow-up.⁸ One study specifically evaluating the test at 64 to 70 days of gestation found it correctly identified every ongoing pregnancy, with 100 percent sensitivity.⁹ A comparison of two commercially available low-sensitivity tests found ongoing pregnancies were uncommon (0.4 percent in that sample) and that both formats detected them, though services should also emphasize the clinical signs that suggest a failed abortion.¹⁰

Symptom-based self-assessment also plays a role. A study in Nepal found that women’s self-assessment agreed with providers’ clinical determinations about 85 percent of the time, and roughly two thirds of those who needed further care correctly identified it themselves.¹¹ Another study found that the strategy of combining symptom evaluation with a home pregnancy test worked well enough that routine clinical follow-up after every medication abortion may not be necessary for safety.¹² Still, the data also show that a meaningful minority of people misinterpret the tests or miss warning signs, so having a clinician available is an important safety net rather than a formality.

What Happens Next if It Failed

Depending on the regimen and the reason for failure, roughly 2 to 10 percent of people who have a medication abortion will eventually need a surgical procedure, whether for a continuing pregnancy, incomplete abortion, heavy bleeding, or persistent symptoms.¹³ Vacuum aspiration (sometimes called suction aspiration) is the most common follow-up procedure. It is a brief outpatient procedure that empties the uterus and resolves the issue in nearly all cases.

In some situations, clinicians offer a second course of misoprostol instead of surgery. This approach has mixed results. One study of patients who received a repeat dose of misoprostol for a missed abortion found success in only about 47 percent of cases.¹⁴ So a second round of medication is an option, but it works less reliably than the first round, and surgical aspiration remains the definitive backup.

Complications from post-abortion care are generally uncommon. A narrative review cataloging post-abortion complications includes bleeding, retained tissue, uterine perforation (which is a surgical risk, not a medication one), and infection.¹⁵ These are manageable conditions when caught early, which circles back to why recognizing failure signs and pursuing follow-up matters.

Risks to the Fetus if the Pregnancy Continues

This is the question that causes the most anxiety: if someone takes the abortion pills and the pregnancy survives, has the fetus been harmed? The two drugs in the regimen, mifepristone and misoprostol, carry different risk profiles, and the evidence is more concerning for misoprostol than for mifepristone.

Misoprostol exposure in the first trimester has been linked to a specific pattern of birth defects. A meta-analysis found sharply elevated risks of Möbius sequence, a rare condition involving facial nerve paralysis, and terminal transverse limb defects, where fingers or toes do not fully develop.¹⁶ A Brazilian study comparing mothers of infants with Möbius syndrome found that about half had used misoprostol in the first trimester, versus 3 percent among a comparison group of mothers whose infants had neural-tube defects.¹⁷ A prospective follow-up study estimated the incidence of misoprostol’s specific pattern of malformations at about 2 percent among exposed pregnancies, and noted that brainstem injuries might be added to the recognized pattern.¹⁸

The evidence on mifepristone alone is less alarming but not fully reassuring. A 2024 systematic review concluded that the data did not support classifying mifepristone as a teratogen, though some congenital anomalies appeared in the reviewed cases and could not always be attributed to other causes.¹⁹ A separate systematic review and meta-analysis stated that the potential teratogenic effect of mifepristone cannot be ruled out.²⁰ An observational study of 105 pregnancies that continued after mifepristone exposure found an overall major malformation rate of 4.2 percent, which is slightly above background rates but based on a small sample.²¹

What this means practically is that someone who took both medications and still has a continuing pregnancy should discuss these risks with a clinician. The decision about whether to proceed with termination or continue the pregnancy is personal and depends on the specific circumstances, but the evidence suggests the fetal risks are not trivial, especially from misoprostol exposure.

The Ectopic Pregnancy Problem

Medication abortion does not treat ectopic pregnancies, and taking the pills when the pregnancy is located outside the uterus is one of the more dangerous failure scenarios. Because the medication works on uterine tissue, it has no effect on an embryo growing in a fallopian tube, at a cesarean scar, or in another abnormal location. The bleeding that occurs after taking the pills can mask the symptoms of an ectopic pregnancy, leading to delayed diagnosis.

A study at one center found that among patients with pregnancy of unknown location who were managed expectantly, about 8 percent were ultimately treated for ectopic pregnancy, including four ruptured ectopics.²² Another analysis found that among patients presenting with ectopic pregnancies, a large proportion had previously taken medication abortion pills without prior confirmation of an intrauterine pregnancy, and that the clinical picture in these cases was frequently atypical, making diagnosis harder.²³ A case report described a cesarean scar ectopic pregnancy diagnosed after a failed no-test medication abortion at just four weeks of gestation.²⁴

This is the main clinical argument for confirming an intrauterine pregnancy with ultrasound before dispensing medication abortion pills. When medications are provided without an ultrasound, which happens in some telemedicine and self-managed models, a missed ectopic is a small but real risk. If you experience severe one-sided abdominal pain, shoulder-tip pain, or feel faint after taking the pills, an ectopic pregnancy needs to be ruled out immediately, regardless of any bleeding that seemed to indicate the pills were working.

Factors That Make Failure More Likely

Gestational age is the most consistent predictor. The further along the pregnancy, the lower the success rate. In the large buccal misoprostol study, success was significantly higher below the median gestational age of 44 days compared to above it.¹ The proportion of pregnancies that continued one to two weeks after mifepristone alone varied widely by dose and gestational age, ranging from 8 to 46 percent.²⁵

Body weight is another factor that receives less attention than it should. A study comparing obese and non-obese women undergoing medication abortion for missed abortion found that success occurred in 45 percent of the obese group versus 69 percent of the non-obese group, with the obese group also taking longer to reach uterine evacuation.²⁶ A case report of medication abortion failure in a patient with class III obesity and twin gestation suggested that altered drug processing in the body may reduce effectiveness, though more research is needed before making dosing recommendations.²⁷

Twin or multiple pregnancies, the specific misoprostol regimen used (oral versus buccal or vaginal), and how precisely the protocol was followed also influence outcomes. No single risk factor guarantees failure, but someone with multiple risk factors should be aware that the probability of needing a follow-up procedure is higher than the headline success rates would suggest.

The “Abortion Reversal” Claim

Some providers and advocacy groups promote the idea that if you take mifepristone but not yet misoprostol and change your mind, taking high-dose progesterone can “reverse” the abortion. The evidence behind this claim is weak. A systematic review concluded that there is insufficient evidence to determine whether progesterone treatment after mifepristone results in a higher proportion of continuing pregnancies compared to simply doing nothing.²⁵ A more recent systematic review reached a similar conclusion: based on mostly poor-quality data, the ongoing pregnancy rate after progesterone treatment does not appear significantly higher than after mifepristone alone.²⁸

This matters because mifepristone alone does not end every pregnancy. Remember, the proportion of pregnancies continuing after mifepristone without misoprostol ranges from 8 to 46 percent depending on the dose and timing. Some pregnancies will survive mifepristone regardless of whether progesterone is given. Without a proper control group, any study showing pregnancies continuing after “reversal” treatment cannot distinguish between the drug’s effect and the pregnancy simply having survived on its own. Despite several U.S. states mandating that patients be informed about reversal as an option, the scientific consensus is that this is not an evidence-based intervention.

Access and Legal Considerations After a Failed Medication Abortion

In places where abortion is restricted, a failed medication abortion creates a complicated situation. The person still needs medical care, whether that means completing the abortion surgically or managing an incomplete abortion, but they may fear legal consequences for seeking it. Following changes to abortion law in the United States, researchers have predicted that more patients will present to emergency departments with complications from self-managed abortions, and that some will be reluctant to report what happened due to fear of prosecution.²⁹

From a clinical standpoint, the treatment for a failed medication abortion is the same as for a miscarriage. Vacuum aspiration for an incomplete medication abortion is medically indistinguishable from the management of an incomplete miscarriage, and emergency clinicians generally treat both the same way. Someone presenting with bleeding and retained tissue after a failed medication abortion does not need to disclose the cause to receive appropriate emergency care. That said, being honest with your provider about what happened, when it is safe to do so, helps them choose the right follow-up plan, including monitoring for the specific complications associated with medication exposure.

When Mifepristone Was Never Taken

A significant number of people worldwide use misoprostol alone to end pregnancies, either because mifepristone is unavailable, unaffordable, or legally inaccessible. This matters for the failure question because misoprostol-only regimens fail far more often. The systematic review noted earlier found that about one in five women using misoprostol alone needed surgical evacuation, and nearly 7 percent had an ongoing pregnancy rather than just retained tissue.² Hospitalization or blood transfusion occurred in under 1 percent, but the higher failure rate means more people end up needing a follow-up procedure.

If you used misoprostol alone and are uncertain whether the abortion worked, the same verification tools apply: low-sensitivity pregnancy tests taken about two weeks later, symptom monitoring, and ultrasound when available. The threshold for seeking follow-up should be lower than with the combined regimen, because the odds of needing additional care are meaningfully higher.