What to avoid after taking Plan B?

Asked by: Dr. Pierre Kub  |  Last update: December 19, 2025
Score: 4.7/5 (20 votes)

There are certain medications and herbal supplements that you should avoid after taking Plan B, as they may lower the efficacy of the drug. These include: Barbiturates (including primidone) Bosentan.

What should you not do after Plan B?

Don't have sex until you start another type of birth control. The morning-after pill doesn't offer lasting protection from pregnancy. If you have sex without protection in the days and weeks after taking the morning-after pill, you're at risk of becoming pregnant. Be sure to start using or resume use of birth control.

Does anything interfere with Plan B?

A number of other medications can make it less effective. Plan B may interact with topiramate (Topamax), carbamazepine (Tegretol, Equetro), and St. John's wort. Efavirenz (Sustiva) and rifampin (Rifadin) can also interact with Plan B.

What cancels out Plan B?

Examples of drugs or herbal products that could decrease the effectiveness of Plan B include barbiturates, bosentan, carbamazepine, felbamate, griseofulvin, oxcarbazepine, phenytoin, rifampin, St. John's wort, topiramate, and certain HIV/AIDS medications.

What things make Plan B less effective?

Things that make Plan B less effective include:
  • Taking it more than 72 hours after unprotected sex or contraceptive failure. ...
  • Taking it with interacting medications. ...
  • Vomiting within 2 hours of taking Plan B can prevent it from working in your body. ...
  • Taking it at certain times of your cycle. ...
  • Taking expired medication.

The Science of 'Plan B' - Emergency Contraception

29 related questions found

What will cause Plan B to fail?

Some reasons Plan B might fail include: Ovulation: Plan B works primarily by delaying or preventing ovulation. If a person ovulates before taking it, they may still get pregnant. Weight: Some studies suggest that Plan B works less well in people with a body mass index (BMI) of over 30 .

What can I drink to prevent pregnancy after unprotected?

Ginger: Consuming ginger in the form of tea is believed to have contraceptive properties as it can induce a period and prevent pregnancy naturally. To prepare ginger tea, you can add crushed or grated ginger to boiling water and let it steep for 5 minutes.

What foods cancel Plan B?

Levonorgestrel Food

You may want to limit your consumption of grapefruit and grapefruit juice during treatment with levonorgestrel.

Does Plan B mess with anything?

There have been no reports of serious problems out of the millions of people who've taken it. After you take the morning-after pill, it's totally normal for your next period to be different from what you're used to. It may come earlier or later, and be heavier, lighter, or more spotty.

What to avoid while on birth control pills?

Medicines That Interfere With Birth Control Pills
  • Antibiotics.
  • Anti-HIV Drugs.
  • Anti-Fungal Medications.
  • Anti-Seizure Drugs.
  • Modafinil (Provigil)
  • Herbal Remedies.

What makes Plan B less likely to work?

Emergency contraception does not work after ovulation has already occurred. The longer you wait to take emergency contraception after unprotected sex, the less likely it is to help because it's possible that ovulation has already occurred.

How long does Plan B stay in your system?

Plan B leaves the body through elimination of urine and feces. About 45% of emergency contraception leaves the body through urine, and about 35% leaves the body through feces. Small amounts of this medication can stay in the body for up to 5 days after consumption.

Does alcohol mess with Plan B?

There is no known loss in efficacy when drinking alcohol after taking ECPs. The National Institute on Alcohol Abuse and Alcoholism doesn't list any contraceptive methods on its list of commonly used prescription and over-the-counter medicines that interact with alcohol.

What not to mix with Plan B?

The following medications can make Plan B less effective:
  • Anti-HIV drugs.
  • Anticonvulsants.
  • Antibiotics.
  • Rifampicin.
  • Rifabutin.
  • Griseofulvin.
  • St. John's wort.
  • Ulipristal acetate.

Is it safe to come inside after Plan B?

The morning-after pill (AKA Plan B or emergency contraception) can help prevent pregnancy when you take it after having unprotected sex. But, it won't prevent pregnancy for any sex you may have after taking it. So if you use the morning-after pill and then have unprotected sex, you'll need to take it again.

How long will I feel bad after Plan B?

Plan B One-Step (levonorgestrel) is a form of emergency contraception that can prevent pregnancy after birth control failure or unprotected sex (also known as condomless sex). 1 While it is generally considered safe and effective, people who take it may experience mild side effects that typically pass within 24 hours.

What would make a Plan B fail?

Other possible reasons for failure include: Vomiting within two hours of taking it. Weight (levonorgestrel may be less effective if you have overweight) Interaction with other medications making it less effective (like certain barbiturates or St. John's wort)

Does cramping after Plan B mean it's working?

Cramping after Plan B does not necessarily mean it is working. Taking Plan B causes hormone fluctuations which can cause side effects. Lower abdominal cramps are one of the side effects of Plan B. However, you cannot rely on these side effects to tell if the emergency contraception worked.

Can Plan B cause weight gain?

Plan B shouldn't cause weight gain or weight loss. Body weight changes weren't reported by people taking Plan B in its original clinical trials. In fact, most forms of birth control don't cause weight gain. It's possible to experience bloating when taking progestin-based birth control.

What not to eat after taking the contraceptive pill?

Most foods and supplements are safe to combine with the pill. But a few may affect how well birth control pills work. Eating large amounts of grapefruit products can raise your risk of birth control pill side effects. Some research suggests that soy products may change hormone levels in the body.

Can you be pregnant if you took Plan B and got your period?

Some irregular bleeding — also known as spotting — can happen after you take the morning-after pill. It's also normal for your period to be heavier or lighter, or earlier or later than usual after taking EC. But once you get your period after taking emergency contraception (EC), that's a sign that you're not pregnant.

Will Plan B work if he came in me twice in one day?

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.

How to wash out sperm to prevent pregnancy?

If someone prefers to clean their vagina and vulva after sex, the safest way to do so is with unscented soap and warm water. Some people claim that urinating, showering, bathing, or using vinegar may help remove semen. However, once semen passes through the cervix, there is no scientifically proven way to remove it.

What can I do to stop 1 week of pregnancy?

The “abortion pill” is the popular name for a safe and effective way to end an early pregnancy using a combination of two medicines: mifepristone and misoprostol. Mifepristone stops the pregnancy from growing. After taking mifepristone, you take a second medicine (misoprostol) up to 48 hours later.

How long does the morning-after pill last in your system?

The morning-after pill, a go-to for unexpected contraception hiccups, typically remains active in your system for a few days, gradually dissipating within 24 to 48 hours post-consumption. It offers a temporary solution for unplanned situations, such as unprotected sex or contraceptive failure.