Emergency Contraception

1 medicine

Emergency contraception reduces the chance of pregnancy after unprotected sex; the standard option, levonorgestrel, works best when taken within 24 hours.

Plan B

Levonorgestrel

1.5mg

Plan B is a womens health medication containing Levonorgestrel, available as 1.5mg tablets.

from $9.70 / tablet View

Key facts

  • Emergency contraception reduces the chance of pregnancy after unprotected sex or a failed contraceptive method. It is a backup option, not a routine method of birth control.
  • Timing decides how well it works. The main option, levonorgestrel, delays or prevents ovulation and works best within 24 hours, with some effect up to 72 hours.
  • It will not end an existing pregnancy, and it has no effect once ovulation has already happened or an egg has implanted.
  • Mild nausea, headache, or spotting can follow. Take a pregnancy test if your next period is more than a week late.

How quickly it needs to be taken

Timing is the single biggest factor in whether emergency contraception works. Levonorgestrel delays or prevents ovulation, and its effectiveness drops the longer you wait after unprotected sex. Taking it within 24 hours gives the highest success rate; effectiveness falls steadily after that, and it is not generally recommended beyond 72 hours. It sits within the women's health range of medicines alongside routine contraception options.

What it does not do

Emergency contraception does not end an established pregnancy. It works by stopping or delaying ovulation, so it will not help if ovulation has already occurred that cycle, and it has no effect on a fertilised egg that has already implanted. If you are already pregnant, it will not disrupt the pregnancy.

What to expect afterward

Some people notice mild nausea, a headache, or irregular spotting in the days after taking it. Your next period may arrive earlier or later than usual, and its flow can be lighter or heavier than normal. If your period is more than a week late, take a pregnancy test to check whether the dose worked.

When to see a doctor

See a doctor or pharmacist if you vomit within two hours of taking the dose, since you may need a repeat dose, or if your period is very late or unusually light. A pharmacist can also talk through more effective ongoing contraception if you want one going forward.

This page is educational and does not replace advice from a doctor or pharmacist who knows your health history.