How it works
Emergency pills work mainly by delaying or preventing ovulation, so they are not abortion pills and will not end an existing pregnancy. A copper IUD stops sperm from fertilizing an egg and may also stop a fertilized egg from implanting.
Anyone who has had unprotected sex or a contraceptive failure, such as a split condom or missed pills, and wants to lower the chance of pregnancy.
How effective is it?
Typical use
Varies
Copper IUD over 99%; pills reduce risk
Perfect use
n/a
No yearly rate: this is a one-off backup.
The copper IUD is the most effective option; both pills work better the sooner they are taken
See how it ranks against every method in the effectiveness chart.
How to use it
Act quickly: a copper IUD can be fitted up to 5 days (120 hours) after unprotected sex, or up to 5 days after the earliest likely date of ovulation; it is the most effective option and needs a clinic or doctor.
Ulipristal acetate pills can be taken up to 120 hours (5 days) after sex; levonorgestrel pills up to 72 hours (3 days), and work best the sooner they are taken.
Get pills from a pharmacy (over the counter in many countries, including the US, UK and India), a sexual health clinic or a doctor; a pharmacist may suggest a different option or dose depending on your weight, medicines or timing.
If you vomit within 3 hours of taking a pill, get advice, as you may need another dose.
Use condoms until your regular contraception is working, and take a pregnancy test 3 weeks after the unprotected sex, or sooner if your period is more than 7 days late or unusually light.
Pros and cons
Advantages
- Can prevent pregnancy after sex has already happened
- Pills are available without a prescription in many countries
- The copper IUD is over 99% effective and can stay in as long-term contraception
- Safe for most people, including those who can't use regular hormonal contraception
- Can be used more than once if needed
Disadvantages
- Pills are less effective than the copper IUD and less effective the longer you wait
- Pills do not protect against pregnancy for the rest of the cycle
- Levonorgestrel may work less well at higher body weight or BMI
- The copper IUD needs an appointment for fitting, which can be hard to get quickly
- Does not protect against STIs
Effect on periods: Your next period may come earlier or later than usual.
Possible side effects
- Nausea or, less often, vomiting
- Headache or tiredness
- Tummy pain or breast tenderness
- Spotting or a change in the timing of your next period
- With a copper IUD: cramping when fitted and possibly heavier periods
Who it may not suit
A clinician checks your medical history before you start. This list is not complete.
May not be suitable if
- You take certain medicines, such as some epilepsy, HIV or TB medicines or St John's wort, which can make pills less effective (a copper IUD may be advised)
- You have severe asthma treated with steroid tablets (ulipristal may not suit)
- You have already taken a different type of emergency pill in the same cycle, or recently took hormonal contraception (this affects which pill suits)
- You have certain conditions of the womb or a current pelvic infection (an IUD may not suit)
Get medical help if
- Your period is more than 7 days late, or unusually short or light
- You have sudden or severe lower tummy pain, which could be an ectopic pregnancy and needs urgent care
- You vomited within 3 hours of taking the pill
- You need advice on restarting your regular contraception
Frequently asked questions
How long after sex can I use emergency contraception?
A copper IUD can be fitted up to 5 days (120 hours) after sex, ulipristal acetate pills can be taken up to 120 hours after, and levonorgestrel pills up to 72 hours after. All work better the sooner they are used.
Is the morning-after pill an abortion pill?
No. Emergency pills work mainly by delaying ovulation, so they prevent pregnancy from starting. They do not end an existing pregnancy and are not the same as medication abortion.
Does body weight affect the morning-after pill?
Levonorgestrel may be less effective in people with a higher body weight or BMI. A copper IUD is not affected by weight, and a pharmacist may suggest a different option or dose, so mention your weight when you ask.
When can I restart my regular contraception after emergency contraception?
After levonorgestrel you can usually restart hormonal contraception straight away. After ulipristal, UK guidance (FSRH) advises waiting 5 days before restarting hormonal contraception, because it can make ulipristal less effective; use condoms or avoid sex until your method is working again.
Do I need a prescription for the morning-after pill?
In many countries, including the US, the UK and India, levonorgestrel pills are available over the counter at pharmacies. Rules for ulipristal vary: it is pharmacy-available in the UK but needs a prescription in the US.
Sources
Reviewed 1 November 2026. We link to the guidance itself so you can check it.