Does Alcohol Affect Plan B? The Facts

If you are reading this, you likely took Plan B and then had a drink, or you are planning to take it and wondering if that glass of wine matters. The short answer is no — alcohol does not stop Plan B from working. The emergency contraceptive pill prevents pregnancy based on hormones, and alcohol does not change how those hormones act on your body. However, alcohol can still complicate the situation in ways that matter, and understanding those differences is what this article is about.

Does Alcohol Affect Plan B’s Effectiveness?

No. Alcohol does not directly reduce the effectiveness of Plan B or other levonorgestrel emergency contraceptives. The medication works by delaying ovulation, and alcohol does not interfere with that hormonal mechanism.

What alcohol can do is make you vomit. If you vomit within two hours of taking Plan B, the pill may not have been fully absorbed, and it may not work. This is the real risk — not a chemical interaction, but a physical one.

Vomiting is the only way alcohol meaningfully threatens Plan B’s effectiveness, and it only matters if it happens within that two-hour window after you take the pill.

How Plan B Actually Works

Plan B contains levonorgestrel, a synthetic form of the hormone progesterone. It works primarily by delaying ovulation. If ovulation has not happened yet, delaying it means the egg is released later, after sperm have died off. Sperm can survive in the reproductive tract for up to five days, so the timing matters.

The pill does not end a pregnancy. It does not work if ovulation has already occurred. It is not an abortion pill, and it has no effect on an implanted embryo.

This is why timing is everything. Plan B is most effective when taken within 72 hours of unprotected sex, and it works best the sooner it is taken. Some research suggests it may have some effect up to 120 hours, but the evidence for effectiveness drops significantly after the first 72 hours.

Alcohol does not change any of this. It does not speed up or slow down how your body processes levonorgestrel in a way that matters clinically.

What the Research Says About Alcohol and Plan B

There are no large human trials specifically testing alcohol and Plan B together. That does not mean the combination is dangerous — it means researchers have not needed to study it because there is no biological reason alcohol would interfere with the drug’s mechanism.

Levonorgestrel is processed by the liver, and alcohol is also processed by the liver. Some people assume this means alcohol could speed up the breakdown of the medication, leaving less of it in your system. The evidence does not support that concern at the doses of alcohol people typically consume.

The liver processes alcohol and levonorgestrel through different pathways. Occasional drinking does not meaningfully alter how your body uses emergency contraception. Chronic heavy alcohol use can affect liver function over time, but that is a different situation from having one or two drinks around the time you take Plan B.

The Real Risk: Vomiting Within Two Hours

This is the one scenario where alcohol can cause Plan B to fail. If you drink enough to vomit, and that vomiting happens within two hours of taking the pill, the medication may not have been fully absorbed.

If this happens, the standard guidance is to take another dose. The packaging for Plan B does not include this instruction, but it is the accepted clinical practice based on how the medication is absorbed.

If you are concerned you may vomit, some clinicians recommend asking your pharmacist about an anti-nausea medication. This is not a standard recommendation for everyone — it is a practical option for people who are prone to nausea or who have had a reaction to hormonal medication before.

Nausea is a known side effect of Plan B itself, affecting a meaningful number of people who take it. Adding alcohol to that can make nausea worse. You do not need to be vomiting from alcohol to feel unwell — the combination can simply make you miserable even when it still works perfectly.

Does Drinking Make Plan B Less Effective If You Are Overweight?

There is separate evidence that body weight may affect how well levonorgestrel emergency contraceptives work. Some studies suggest that Plan B may be less effective in people who weigh more than about 165 pounds, and possibly less effective in people with a BMI over 25 or 30.

Alcohol does not interact with this. Drinking does not make the weight-related effectiveness issue worse, and it does not make it better.

If you weigh more than 165 pounds and you need emergency contraception, the alternative is ella (ulipristal acetate), which requires a prescription. Some research suggests ella may be more effective than Plan B in people with higher body weight. This is a conversation to have with a doctor or pharmacist before you need emergency contraception, not in the moment.

This is not directly related to alcohol, but it matters because it is a common misunderstanding. People sometimes assume that drinking was the reason Plan B failed when the real issue was weight or timing.

Alcohol Does Not Cause Plan B to Fail — But It Can Cause You to Make Mistakes

This is the less obvious risk. Alcohol impairs judgment. If you are drunk enough to need emergency contraception, you may also be drunk enough to forget to take the pill, take it late, or take it incorrectly.

Plan B requires precise timing. Taking it at 72 hours is less effective than taking it at 24 hours. If alcohol delays your decision-making, you may miss that window entirely.

There is also the risk of taking a second dose by mistake. If you forget you already took Plan B and take another one, you will likely experience more nausea and more disruption to your menstrual cycle. It will not harm you, but it is not pleasant.

The practical advice is simple: if you need Plan B, take it as soon as possible. Do not wait until you sober up if you can avoid it. The medication works regardless of whether you have been drinking, and the only reason to wait is if you think you might vomit immediately.

What to Do If You Took Plan B and Then Drank

If you already took Plan B and then had alcohol, nothing needs to change. The pill is still working. You do not need another dose just because you drank.

If you drank and then vomited within two hours of taking the pill, contact a pharmacist or a healthcare provider. They will likely advise you to take another dose. Do not take a second dose without checking first, because the instructions are different depending on the exact medication you used.

If you are within the 72-hour window and you are unsure whether the first dose stayed down, it is better to ask a professional than to guess. Pharmacists can answer this question without a doctor’s visit, and they are trained to handle exactly this kind of situation.

Common Myths About Alcohol and Emergency Contraception

Myth: Alcohol cancels out the hormones in Plan B.
False. There is no mechanism by which alcohol neutralizes levonorgestrel.

Myth: You should not take Plan B if you have been drinking.
False. The opposite is true. If you need emergency contraception, you need it regardless of your blood alcohol level. Waiting makes it less effective.

Myth: Drinking while taking Plan B causes permanent damage.
False. There is no evidence of any lasting harm from combining occasional alcohol use with emergency contraception.

Myth: You need to drink lots of water or “flush” the alcohol out before taking Plan B.
False. Hydration is generally good for you, but it has no effect on how Plan B works.

When to Take a Pregnancy Test After Plan B

Plan B is not 100% effective. No emergency contraceptive is. If your next period is more than seven days late, take a pregnancy test.

Alcohol can also delay your period if you have been drinking heavily, which can make the situation confusing. If you get a negative pregnancy test but your period still does not come, wait a few days and test again, or see a healthcare provider.

Plan B can also cause spotting or changes to your next period that are not pregnancy-related. This is a known side effect. The only way to know for certain is to test.