Plan B (Levonorgestrel) Emergency Contraception – Patient Information (UK)

Plan B containing levonorgestrel is an emergency contraceptive medicine used to help reduce the chance of pregnancy after unprotected sex or contraceptive failure. It is intended for emergency use and should be taken as soon as possible.

This guide is designed to be patient-friendly and explain how Plan B works, how to take it, safety considerations, and what to expect. It is written for the United Kingdom audience.

Basic product information

Brand names and pack sizes may vary. Always check your specific product packaging and the instructions included with your medicine.

How Plan B works (mechanism of action)

Levonorgestrel is a synthetic hormone similar to progesterone. Plan B works mainly by affecting events around ovulation (the release of an egg).

• Delays ovulation: By influencing hormonal signalling, levonorgestrel can help prevent or delay the release of an egg.
• May affect sperm and fertilisation: Changes in cervical mucus can make it harder for sperm to reach the egg.
• Most effective before ovulation: If ovulation has already happened, Plan B is less likely to work.

Plan B does not work by causing an abortion. It helps prevent pregnancy from occurring in the first place.

Pharmacokinetics (how the body processes it)

After taking levonorgestrel by mouth, it is absorbed into the bloodstream and metabolised mainly in the liver. While exact values can vary between individuals, the general process is:

• Absorption: Levonorgestrel is absorbed from the gut after swallowing the tablet.
• Distribution: It circulates in the blood and binds to proteins.
• Metabolism: It is broken down (metabolised) in the liver.
• Elimination: Metabolites are removed from the body, primarily via the kidneys and/or bile.

Because the medicine is taken as a single dose for emergency contraception, it is designed to act quickly during the window before ovulation.

Typical use in the UK

In the UK, Plan B is used after situations where pregnancy risk is increased, for example:

• Unprotected sex
• Contraceptive failure (e.g., condom broke, slipped, or was used incorrectly)
• Missed emergency contraception window for another method (or if Plan B was chosen)
• Late or missed doses of oral contraception (depending on the situation)
• Sex without reliable contraception

Emergency contraception can be used at any time during the cycle, but effectiveness is generally higher when taken earlier.

When to take Plan B (timing and what to do if you’re late)

The sooner you take it, the better. Plan B is most effective when taken as soon as possible after unprotected sex. Many guidance documents describe greatest effectiveness within 24 hours, with decreasing effectiveness up to 72 hours.

If you can’t take it within 72 hours, consider seeking advice—other emergency contraception options may still be effective for longer.

• Ideal: Take the tablet immediately after unprotected sex.
• Later use: Still take it as soon as you remember if the time window has not fully passed for your product.
• Vomiting: If you vomit shortly after taking it, you may need another dose—see “Practical use tips” below.

Dosing (how much to take)

The most common emergency contraception dose for levonorgestrel (Plan B) is:

• One tablet, usually 1.5 mg levonorgestrel total, taken by mouth as a single dose.

Follow the dosing instructions on your pack or the patient information leaflet supplied with your medicine. If your product contains a different strength or dosing schedule, use the exact instructions for that specific product.

Do not exceed the recommended emergency dose. If you think you have taken too much, seek urgent medical advice or contact NHS services.

Food interactions

Food is generally not a major barrier to levonorgestrel effectiveness. You can typically take Plan B with or without food. However, if you feel nauseated, taking it with a small snack may help.

Practical point: If you vomit soon after taking the tablet (commonly within a few hours—check your leaflet), the tablet may not have been fully absorbed and you may need to take another dose or seek advice.

Alcohol and medicine interactions

Alcohol

Moderate alcohol use is not known to directly reduce the hormonal effectiveness of levonorgestrel. However, alcohol can:

• Increase nausea or vomiting (which may reduce absorption)
• Make it harder to remember timing
• Impact decision-making

If you have been drinking, focus on taking the medicine as soon as possible and seek advice if you vomit.

Other medicines (important interactions)

Some medicines can reduce the effectiveness of levonorgestrel by increasing liver metabolism. Examples include:

• Enzyme-inducing medicines such as certain antiepileptics (e.g., carbamazepine, phenytoin), some medicines for HIV (certain protease inhibitors), and rifampicin or related antibiotics
• Herbal products such as St John’s wort (Hypericum perforatum)

If you are taking any enzyme-inducing medicines, emergency contraception may be less effective with Plan B. In many cases, another method (such as a copper IUD) may be recommended, or medical advice may be needed promptly. If you’re unsure whether your medicines interact, you can seek advice from a pharmacist or clinician.

For routine medicines not listed above, interactions are less likely. Still, it’s sensible to check the leaflet or ask a pharmacist if you take regular medication.

Indications (when Plan B is appropriate)

Plan B (levonorgestrel) is indicated for use as emergency contraception after:

• Unprotected intercourse
• Contraceptive failure (e.g., condom issues, missed pills in certain circumstances)
• Situations where contraception was not used reliably

It can be used by many people, but individual circumstances (including timing in the cycle, weight/BMI, and interacting medicines) can affect effectiveness. If you have concerns, get advice quickly.

Safety profile and side effects

Plan B is widely used and is generally well tolerated. Side effects are usually mild and temporary.

Common side effects

• Nausea
• Vomiting
• Headache
• Dizziness
• Breast tenderness
• Lower abdominal pain or cramps
• Fatigue
• Changes to bleeding (spotting or changes in period timing)

Menstrual changes (what to expect)

• Your next period may come earlier or later than expected.
• You may have spotting for a few days after taking it.
• Flow can be lighter or heavier than usual.

When to seek medical advice urgently

Contact medical services promptly if you experience any of the following:

• Severe or persistent lower abdominal pain (especially with dizziness or fainting)
• Fainting or severe unusual symptoms
• Possible pregnancy symptoms with significant pain (to rule out ectopic pregnancy)

While emergency contraception reduces the likelihood of pregnancy overall, it does not fully eliminate the risk. If you become pregnant, it’s important to seek medical evaluation, especially if pain is severe.

Overdose

Taking more than the recommended dose is not advised. If you believe you have taken too much, seek advice from NHS services or a pharmacist for guidance.

Practical use tips (getting the best outcome)

• Take it as soon as possible: Don’t wait for “later that day” if you can take it now.
• Check your product leaflet: Confirm the strength and timing window for your specific pack.
• If you vomit soon after taking it: You may need another dose. Consult the leaflet or a pharmacist for the exact timing guidance.
• Use condoms (or avoid sex) until you’re protected again: Plan B does not provide ongoing contraception for future sex after you take it. Use reliable contraception immediately if you have sex again.
• Consider long-acting contraception: If emergency contraception is needed more than once, a longer-term method may be more suitable—discuss options with a healthcare professional.
• Don’t delay pregnancy testing: If your period is late, take a pregnancy test as advised below.

Effectiveness considerations (including timing, weight, and cycle)

Levonorgestrel emergency contraception works best when taken early, before ovulation. Effectiveness can be reduced by:

• Time elapsed since unprotected sex (effectiveness decreases as time passes)
• Timing in the menstrual cycle (if ovulation has already occurred, it may be less effective)
• Body weight/BMI (some studies suggest reduced effectiveness at higher weights)

If you have higher BMI, are near the time of expected ovulation, or are taking enzyme-inducing medicines, consider contacting a pharmacist/clinician quickly. Other emergency options may be more effective in some situations.

After taking Plan B: what to expect and when to test

After using emergency contraception:

• Watch your next period: It may come earlier or later.
• If your period is more than a few days late: Take a pregnancy test.
• If you have symptoms of pregnancy (e.g., persistent nausea, breast tenderness, unusual fatigue), take a pregnancy test even if your period is not late.
• If the test is positive: Seek medical advice for further assessment.

If you have concerns or want personalised advice, you can contact a pharmacist or use NHS services.

Alternative emergency contraception options

Depending on timing, individual factors, and access to services, there are alternatives to levonorgestrel. These can include:

• Copper IUD (coil): Often the most effective emergency option and can be inserted within a longer time window after unprotected sex. It provides ongoing contraception afterward if left in place.
• Ulipristal acetate: Another oral emergency contraceptive option that may maintain effectiveness for longer than levonorgestrel in some circumstances.
• Repeat dosing considerations: If you have further unprotected sex after taking Plan B, levonorgestrel does not protect for that future sex. A clinician or pharmacist can advise on what to do next.

If you’re unsure which option is best for you, it’s a good idea to speak with a pharmacist or clinician promptly.

Market and legal context in the United Kingdom

In the UK, emergency contraception is part of routine sexual health care. Levonorgestrel-based products have been used for many years and are accessible through multiple routes. Availability can depend on stock levels, product formulation, and pharmacy policies.

Key points relevant to UK access:

• Pharmacy access: Many people can obtain emergency contraception directly from community pharmacies.
• Online services: Some online pharmacies may supply emergency contraception, subject to appropriate checks and regulatory requirements.
• Clear instructions: The product leaflet and packaging should be provided and followed.

If you have questions about suitability, interacting medicines, or timing, pharmacists in the UK can provide immediate guidance.

Recent guidance (UK context)

UK healthcare guidance generally emphasizes:

• Take emergency contraception as soon as possible after unprotected sex.
• Consider the most effective option for the timing of intercourse and individual circumstances.
• Be aware of potential drug interactions (especially enzyme-inducing medicines).
• Offer follow-up and counselling where possible, including contraception after emergency contraception.

Guidance can be updated over time. For the most current advice, consult reputable UK sources such as NHS services or your local sexual health clinic, or speak with a pharmacist.

Delivery and availability (online pharmacy)

Availability can vary by location and supplier. When ordered online, delivery times depend on the carrier, region, and the dispatch schedule. Many customers aim to receive emergency contraception quickly due to the importance of timing.

• Check expected delivery: Review the estimated delivery window at checkout.
• Plan for privacy: Packaging is typically discreet.
• Keep the leaflet: Store it with your medicine for reference.
• Ensure suitability: If you’re unsure about interactions or timing, seek advice from a pharmacist promptly.

If you need help finding the fastest option in your area, you can contact a local pharmacy or sexual health service.

FAQ about Plan B (Levonorgestrel) – UK

1) Can I take Plan B more than once?

You can take levonorgestrel emergency contraception again if needed, but it is intended for emergency use. Repeated use may indicate that a more reliable ongoing contraception method would be helpful. Consider speaking to a pharmacist or clinician about longer-term options.

2) Does Plan B work if I’m already ovulating?

Plan B works mainly by delaying ovulation. If ovulation has already occurred, effectiveness may be reduced. Timing is therefore important—taking it as soon as possible increases the chance of preventing pregnancy.

3) What if I have sex again after taking Plan B?

Plan B does not provide protection for future sex acts. Use condoms or another reliable method for subsequent sex until you start/continue a dependable contraception plan.

4) Will Plan B affect my next period?

Yes. Your next period may come earlier or later than usual, and you may notice spotting. If your period is significantly late or you have pregnancy symptoms, take a pregnancy test and seek advice if needed.

5) How soon should I take a pregnancy test?

If your period is late (beyond what is normal for you) or you develop symptoms of pregnancy, take a test as soon as you can. If negative but your period still doesn’t arrive, repeat testing according to the test instructions or seek advice from a pharmacist/clinician.

6) Can I take Plan B if I’m breastfeeding?

Levonorgestrel is generally considered compatible with breastfeeding. If you have questions, you can ask a pharmacist for guidance specific to your situation. Follow the instructions for your product.

7) Will Plan B interact with my medications?

Some medicines can reduce effectiveness, especially enzyme-inducing medicines (certain anti-epileptics, rifampicin, and St John’s wort). If you take regular medicines, check the leaflet and consider asking a pharmacist if you’re unsure.

8) Does Plan B cause abortion?

Plan B is not designed to end an existing pregnancy. It is used to prevent pregnancy by acting mainly on ovulation and related processes.

9) What should I do if I vomit after taking Plan B?

Vomiting shortly after taking the tablet may prevent absorption. Check your leaflet for the exact time window; often, you may need another dose. If you’re unsure, contact a pharmacist for advice.

10) Is Plan B suitable for everyone?

Many people can use levonorgestrel emergency contraception. Suitability depends on factors such as timing, menstrual cycle stage, body weight/BMI, and interacting medicines. If you have concerns, ask a pharmacist or clinician promptly.

Summary

Plan B (levonorgestrel) is an emergency contraceptive option used after unprotected sex or contraceptive failure. It works primarily by delaying ovulation and is most effective when taken as soon as possible. While it is generally well tolerated, menstrual timing may change and side effects like nausea or spotting can occur.

If you need emergency contraception, don’t delay—take the medicine promptly or seek the most suitable option for your circumstances. If you’re worried about interactions, timing, or effectiveness, speaking with a pharmacist can help you make the safest choice.