Plan B (Levonorgestrel) — Emergency Contraception for Australians

Plan B is an emergency contraceptive medicine containing levonorgestrel. It is designed to help reduce the chance of pregnancy after unprotected sex or certain types of contraception failure.

This page provides patient-friendly information about how Plan B works, how to take it, what to expect, and important safety and interaction considerations. If you are unsure which option is best for you, consider speaking with a pharmacist or clinician.

Key Product Information

Note: Product strength and dosing instructions can vary by brand and local availability. Always follow the instructions provided with your specific Plan B product and packaging.

How Plan B Works (Mechanism of Action)

Levonorgestrel is a synthetic hormone similar to progesterone. When taken as emergency contraception, it mainly works by:

• Delaying ovulation: If you have not yet ovulated, levonorgestrel can help postpone the release of an egg.
• Reducing the chance of fertilisation: By delaying ovulation (and potentially affecting cervical mucus and sperm transport), it may reduce the chance that sperm will meet an egg.
• Not reliably stopping an existing pregnancy: If implantation has already occurred, levonorgestrel is unlikely to work. Emergency contraception is most effective before pregnancy begins.

In practical terms, earlier use provides the best chance of preventing pregnancy.

Pharmacokinetics (How the Body Handles Levonorgestrel)

After taking a levonorgestrel tablet:

• Absorption: Levonorgestrel is absorbed through the gastrointestinal tract, typically reaching peak blood levels within a few hours (often within about 2–3 hours, depending on the formulation and individual factors).
• Distribution: It binds to plasma proteins, including sex hormone binding globulin (SHBG).
• Metabolism: The medicine is metabolised primarily in the liver.
• Elimination: Metabolites are excreted mainly via urine and faeces.

Because the main effect is on ovulation timing, the effectiveness of Plan B depends strongly on how close you are to ovulation when you take it.

Typical Use in Australia (When to Take Plan B)

Plan B may be used after any situation where pregnancy risk is increased, including:

• Unprotected sex (including condom failure or missed condom use)
• Contraceptive failure (e.g., a missed pill, late injection, problems with a contraceptive device)
• Sex without a condom when pregnancy is possible
• Rape or sexual assault (if relevant, urgent access to emergency contraception and support services is important)
• Vomiting shortly after taking regular contraception (if this leads to reduced protection, emergency contraception may be considered)

It is intended for emergency use and not as regular contraception.

Timing: How Soon Should You Take Plan B?

Take it as soon as possible. Plan B is more effective the earlier it is taken after unprotected sex. Effectiveness decreases with time.

General guidance:

• Best: within 24 hours
• Still can be used: up to 72 hours after unprotected sex (depending on product guidance and clinical recommendations)

After 72 hours: Some emergency contraceptive options may be more effective, depending on the time since intercourse and your circumstances. A pharmacist or clinician can help you decide what option is most appropriate.

If you’re not sure when you ovulated (or might ovulate), the safest approach is still to take emergency contraception promptly.

How to Take Plan B (Dosing Instructions)

For most Plan B levonorgestrel products used as emergency contraception:

• Adults (and adolescents of appropriate age, per local product instructions): 1.5 mg as a single dose, taken by mouth.
• Timing: Take the dose as soon as possible after unprotected sex.

How to take it:

• Swallow the tablet with water.
• You can usually take it with or without food (see food section below).
• If you vomit soon after taking it (timing depends on the product and clinical advice), you may need to repeat the dose—check the leaflet or ask a pharmacist.

After taking Plan B:

• You can typically continue your usual contraception (if you have it), but emergency contraception does not replace regular ongoing methods.
• Consider using condoms or avoiding unprotected sex until you have resumed reliable contraception.

Food Interactions (Can You Take It With Meals?)

Generally, food does not significantly reduce the effectiveness of levonorgestrel emergency contraception. You may take Plan B with or without food.

What matters more:

• Taking it promptly after unprotected sex
• Avoiding vomiting soon after the dose (if this happens, you may need further advice)

Alcohol and Medicine Interactions

Alcohol

There is no specific “alcohol interaction” that is known to directly cancel levonorgestrel’s emergency contraceptive effect. However:

• Alcohol may increase the likelihood of nausea or vomiting, which could reduce absorption.
• It may affect your ability to follow instructions correctly.

Practical advice: If you choose to drink alcohol, do so in moderation and avoid binge drinking. If vomiting occurs after taking Plan B, seek advice promptly.

Medicine interactions (important)

Some medicines can reduce the effectiveness of levonorgestrel by increasing drug metabolism or altering hormone levels.

• Enzyme-inducing medicines (e.g., certain anti-seizure medicines, some tuberculosis treatments, and some herbal products like St John’s Wort) may reduce effectiveness.
• HIV medicines and other long-term medications may also interact depending on their specific components.
• If you take regular medicines, it is wise to check with a pharmacist to confirm whether there are known interactions.

If Plan B may be less effective:

• Your pharmacist may recommend an alternative emergency contraception option that is not as affected by enzyme inducers.

Always tell a pharmacist about:

• All medications and supplements you are currently taking
• Any recent doses of enzyme-inducing medicines
• Any history of vomiting or diarrhoea around the time of taking emergency contraception

Indications (What Plan B Is Used For)

Plan B (levonorgestrel) is indicated for:

• Emergency contraception to reduce the risk of pregnancy after unprotected sex or contraception failure.
• Use as soon as possible after the event, with diminishing effectiveness as time passes.

It is not intended as ongoing contraception.

How Effective Is It?

Effectiveness varies with how soon you take it, timing in relation to ovulation, and other individual factors.

• Earlier is better: Taking levonorgestrel sooner after unprotected sex improves chances of preventing pregnancy.
• Ovulation timing matters: If you have already ovulated, it may be less effective.
• Body weight/BMI considerations: Some evidence suggests reduced effectiveness at higher body weight for levonorgestrel emergency contraception. If this may apply to you, talk to a pharmacist about the best option.

If you require a higher-reliability emergency option, a pharmacist can discuss alternatives.

Safety Profile and Common Side Effects

Plan B is generally well tolerated.

Common side effects

• Nausea
• Abdominal pain or cramps
• Headache
• Dizziness or tiredness
• Breast tenderness
• Changes in bleeding (spotting or altered timing of your next period)

What to expect with your period

• Your next period may come earlier or later than expected.
• Spotting or light bleeding can occur.
• If your period is more than 7 days late, take a pregnancy test and seek advice.

Serious or urgent symptoms

Seek medical advice urgently if you experience:

• Severe lower abdominal pain that does not improve
• Fainting, shoulder pain, or heavy bleeding
• Symptoms that could suggest ectopic pregnancy (rare, but important to rule out, especially if pain is one-sided)

Emergency contraception does not increase the risk of ectopic pregnancy, but pregnancy that occurs after any emergency contraception should be assessed appropriately.

Practical Use Tips (Maximise Effectiveness)

• Act quickly: The best time to take Plan B is immediately after the event.
• Take the full dose: Do not split it unless your product instructions specifically say so.
• Follow vomiting guidance: If you vomit soon after taking it, you may need another dose—check the patient information or ask a pharmacist.
• Use condoms until regular contraception is reliable: Emergency contraception is not ongoing protection.
• Get pregnancy testing at the right time: If your period is late or you have symptoms of pregnancy, use a home pregnancy test or seek clinical advice.
• Consider ongoing contraception options: A pharmacist can discuss methods such as the pill, patch, ring, implant, injection, or an IUD (see alternatives).

Alternative Emergency Contraception Options

Depending on timing, personal factors, and medicine interactions, other emergency contraception options may be considered:

• Ulipristal acetate (where available): an emergency contraception pill that may remain effective for longer after unprotected sex and may be less affected by some timing factors.
• Copper intrauterine device (IUD): the most effective emergency contraception option and can provide ongoing contraception. It must be fitted by a qualified clinician.
• Repeat dosing considerations: If you have ongoing unprotected sex after taking Plan B, you may need additional emergency contraception. A clinician/pharmacist can advise the safest plan.

Your best option may depend on:

• How long it has been since the event
• Body weight/BMI
• Current medication interactions (especially enzyme-inducing medicines)
• Whether an IUD is acceptable to you

Market and Legal Context for Australia (Overview)

In Australia, emergency contraception products are available through pharmacy channels. Access may vary depending on state/territory and supplier. Many services support convenient purchasing and advice from pharmacists.

Australian healthcare guidance generally emphasises:

• Early access to emergency contraception
• Informed choice regarding the most appropriate option for your timing and health profile
• Pregnancy testing follow-up if your period is late or symptoms occur

Recent guidance trends: Clinical recommendations commonly favour options that maintain effectiveness for longer after unprotected sex and provide alternative strategies when levonorgestrel may be less effective due to timing or medicine interactions. Pharmacists are encouraged to provide updated advice consistent with national and specialty guidance.

Delivery and Availability (Online Pharmacy Considerations in Australia)

Availability of Plan B can vary by stock and brand in the Australian market. Many online pharmacy providers offer:

• Secure online ordering
• Discreet packaging where permitted
• Fast delivery options depending on location

Delivery tips:

• Choose the fastest shipping option available to minimise delay.
• Check product page details for estimated delivery times.
• Ensure you can receive the package promptly, especially if you need it within the shortest timeframe.

If you need emergency contraception urgently and cannot receive delivery quickly enough, consider immediate in-pharmacy options or other locally available urgent care routes.

When to Take a Pregnancy Test

• If your period is more than 7 days late: take a pregnancy test.
• If you have pregnancy symptoms (unusual breast tenderness, nausea, persistent fatigue) or ongoing concerns: consider testing.
• If the pregnancy test is positive or you have severe pain: seek medical advice promptly.

If you had unprotected sex again after taking Plan B, the pregnancy test reflects the most recent risk window. In that case, you may need to test based on timing of the later event as advised.

Frequently Asked Questions (FAQ)

1) Does Plan B work if I already ovulated?

If you have already ovulated, levonorgestrel may be less effective because its main action is to delay ovulation. However, because ovulation timing can be difficult to predict, Plan B can still be worth taking as soon as possible after unprotected sex.

2) Can I take Plan B more than once?

It can be used more than once if emergency contraception is needed again, but repeated use is not ideal as a regular strategy. If you anticipate recurring risk, consider a reliable ongoing contraceptive method or discuss the most suitable emergency option with a pharmacist.

3) Will Plan B stop an abortion that has already started?

Plan B is not intended to end an established pregnancy and is unlikely to work if implantation has already occurred.

4) Will Plan B affect future fertility?

Plan B does not permanently affect fertility. After taking it, your natural cycle should continue, though bleeding patterns may temporarily change.

5) What if I vomit after taking Plan B?

If vomiting occurs soon after taking the dose, absorption may be incomplete. Check the patient information for guidance on whether you need another dose, or ask a pharmacist promptly.

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

Levonorgestrel is generally considered compatible with breastfeeding. For personalised advice, especially if you have concerns or specific medical conditions, speak with a pharmacist.

7) Is Plan B effective for everyone?

No emergency contraception method is 100% effective. Effectiveness depends on timing after unprotected sex, ovulation timing, medicine interactions, and sometimes body weight/BMI. If you’re concerned about reduced effectiveness, ask a pharmacist about alternative emergency options.

8) What about sexually transmitted infections (STIs)?

Emergency contraception does not protect against STIs. Consider STI testing and prevention strategies (such as condoms) after unprotected sex.

9) Can I use Plan B with my regular contraception?

Many people can continue hormonal contraception after taking emergency contraception, but the safest advice depends on what method you’re using and where you are in the cycle. A pharmacist can guide you on whether you need backup contraception and for how long.

10) Are there any people who should avoid levonorgestrel?

Most people can use levonorgestrel emergency contraception. However, if you have a history of serious adverse reactions to levonorgestrel or are taking interacting enzyme-inducing medicines, you should get personalised advice to choose the most suitable emergency option.

Final Notes

Plan B (levonorgestrel) is an emergency contraception option for reducing the chance of pregnancy after unprotected sex or contraception failure. The most important step is to take it as soon as possible and follow the instructions for your specific product.

If you have questions about timing, medicine interactions, or the most effective option for your situation, a pharmacist can help you make an informed choice.