What is the Plan B Pill?

Plan B One-Step is a type of emergency contraception, designed to prevent pregnancy after you’ve had unprotected sex. It’s sometimes called ‘the morning after pill’ which is a misleading name because you don’t have to wait until the morning after to take it. It’s more effective if you take it as soon as possible after unprotected sex. You take one pill which contains 1.5 milligrams of levonorgestrel, a synthetic hormone that’s used in some other types of contraceptive pill in a lower dose.

Plan B is an American brand. In the UK, the morning after pill which works in the same way is called Levonelle. The generic version of Levonelle is called levonorgestrel.

Dr Clair Grainger

Medically reviewed by

Dr Clair Grainger

Last reviewed: 18 Oct 2019

How Does Plan B Work?

Depending upon where you are in your cycle, Plan B One-Step can:

  • Prevent or delay ovulation (when an egg is released from an ovary)
  • Stop any eggs being fertilised

Plan B One-Step is not an abortion pill and will not cause a miscarriage or abortion. If you are already pregnant, taking Plan B One Step or any other emergency contraception will not work.

When Should I Take It?

Plan B One Step is designed to be taken soon after unprotected sex. This includes times when a condom bursts, or if you have had unprotected sex when your contraceptive pill might not have been as effective, e.g. after a stomach upset or missing a pill. If you are unsure whether you need to take emergency contraception please talk to your pharmacist or doctor (either your GP, sexual health clinic or online doctor) as soon as possible.

You can take Plan B One-Step if:

  • You didn’t use any contraception at all.
  • The condom broke or came off.
  • Your contraceptive diaphragm slipped out of place.
  • You realise that you’ve missed a contraceptive pill, patch, ring or injection or have taken this late, or if you are due a new coil or implant of are concerned it is not in the right place. Please check the information in your pill packet or talk to your doctor, nurse or pharmacist if you are using hormonal contraception (including the progesterone-only injection, progesterone-only coil, progesterone-only implant or copper coil) and are unsure if you need emergency contraception.
  • You’ve been sick or had an upset stomach, and you think your pill might not have worked.
  • You are taking any medication that might have stopped your pill from working.

Plan B and any other types of emergency contraception won’t protect you from pregnancy if if you have unprotected sex again after you’ve taken the pill.

Plan B, along with other brands of levonorgestrel morning-after pill works best the faster you take it. This type of emergency contraception is more likely to be effective if you take it very quickly after having unprotected sex. It works best within three days (72 hours) afterwards.

Where Can I Get Plan B?

Plan B One Step isn’t available in the UK, but you can buy it over the counter in the US if you need it. Although Plan B One Step isn’t available in the UK, other brands of levonorgestrel based emergency contraception available in the UK include:

  • Levonelle One Step (available from pharmacies)
  • Consilient (available from pharmacies)
  • Levonelle 1500 (on prescription from a doctor).
  • Upostelle (on prescription from a doctor)
  • Levonorgestrel 1.5mg (available from pharmacies)
  • Ezinelle 1.5mg (available from pharmacies)

In the US, Plan B One-Step can be sold over the counter in pharmacies (drugstores) without a prescription. No proof of age is needed to buy it.

Normally, levonorgestrel containing emergency contraception can’t be sold by a UK pharmacy to a girl under the age of 16 (although there are exceptional circumstances). If you’re under 16 in the UK and you need the morning after pill, you may be able to buy ellaOne (another emergency contraception pill that can be taken up to 120 hours after unprotected sex) if you are of child-bearing age – or you’ll need to see your school nurse, GP, a family planning clinic or a casualty department. Some minor injuries departments within hospitals will also give you the morning after pill. If you are under 16 and having sex you can talk to your GP, teachers, school nurse, youth/support workers, local sexual health clinic or social worker about sex. We would also recommend involving your parents if you can about any treatment, advice or support you seek.

Here are some links that you may find useful:

Child Helpline: http://www.nspcc.org.uk

Helpline: 0808 800 5000 https://www.childline.org.uk/

The Mix Charity: https://www.themix.org.uk/get-support

How Effective is it?

Emergency contraception is not as effective as regular types of contraception, but if you take it within 72 hours after unprotected sex, Plan B One-Step can reduce the risk of pregnancy by up to 89%. Taken within 24 hours it’s about 95% effective.

All levonorgestrel-containing emergency contraceptive pills available in the UK are recommended for up to 72 hours after sex, but are more effective the sooner after unprotected sex they are taken.

How Do You Take Plan B?

You’ll only need to take one pill, and you should take it as soon as you can after you’ve had unprotected sex. If possible you should take it within 12 hours but it can be taken up to 72 hours afterwards.

You can take it with or without food, but if you are sick you will need to take another one straight away as it may not have been properly absorbed.

If you need to use emergency contraception more than 72 hours after sex, you can use ellaOne. ellaOne can be taken within 120 hours of sex. A similar version of this pill is available in the US called ella. Alternatively a copper IUD (copper coil) can be fitted at a sexual health clinic (or some GP surgeries) up to 120 hours after unprotected sex.

Are There Any Side Effects?

Many women take emergency contraception and have no problems with it, but as with all medicines, it doesn’t suit everyone and there can be side effects.

The most common side effects from Plan B One Step include:

  • feeling sick
  • abdominal pain
  • tiredness
  • headaches
  • menstrual changes
  • breast tenderness
  • vomiting and diarrhoea
  • dizziness

After you’ve taken Plan B One-Step, you may also have some unexpected bleeding. This should go away by the time of your next period. Sometimes Plan B One-Step can affect your next period, making it heavier or lighter than usual.

Your period may also come later – or earlier – than expected. If you haven’t had a period after three weeks, take a pregnancy test just to make sure that you’re not pregnant.


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