Most women are familiar with what emergency contraception or morning after pills are, but relatively few are aware of all of the details and nuances. When you need the morning after pill, decisions have to be made quickly. Which pill is right for you, how long you have, and what to expect afterwards can all affect the decision you need to make as well as the outcome.
Here are five things worth knowing before you ever need them.
1. There Are Two Different Morning After Pills - and They Cover Different Time Windows
The two morning after pills available in the UK are ellaOne (ulipristal acetate 30mg) and Levonelle (levonorgestrel 1.5mg). Although both are emergency contraceptives, they each have their unique characteristics which need bearing in mind.
Levonelle is effective for up to 72 hours (three days) after unprotected sex, with effectiveness declining over that period.1 ellaOne is effective for up to 120 hours (five days) and is considered to maintain its effectiveness more consistently across that full window compared to levonorgestrel.2
If you're within the 72 hour window, both options are available to you. Between 72 and 120 hours, only ellaOne is suitable.
2. The Sooner You Take It, the Better It Works
Both morning after pills work primarily by delaying or preventing ovulation. Neither is a form of abortion - they work before fertilisation occurs, and neither has any effect if you're already pregnant.1
Because timing is central to how the pill works, acting quickly is important. Levonelle taken within 24 hours of unprotected sex is estimated to be up to 95% effective. Taken between 25 and 48 hours, this falls to approximately 85% and between 49 and 72 hours, to around 58%.1 ellaOne is thought to maintain stronger effectiveness across its five-day window, though taking it as soon as possible is still recommended.2
Both pills are available without a prescription from UK pharmacies. You can also order emergency contraception online through a registered UK pharmacy without a GP appointment. Getting it quickly is the priority.
3. Your Weight May Affect Which Option Is Most Suitable
This is one of the least widely known considerations around the morning after pill. Evidence suggests that levonorgestrel-based pills may be less effective in women above a certain body weight or body mass index. The Faculty of Sexual and Reproductive Healthcare (FSRH) advises that effectiveness may be reduced in women with a body weight above 70 kg or a BMI above 26.3
For these women, the FSRH recommends either a higher dose of levonorgestrel, switching to ellaOne, or considering a copper intrauterine device (IUD) - which is the most effective form of emergency contraception regardless of weight and can be kept long-term as continual contraception.3
If you're unsure which option is right for you, ask the pharmacist before purchasing. They can advise based on your individual circumstances.
4. Side Effects Are Normal - and a Delayed Period Doesn't Mean It Has Failed
After taking the morning after pill, it's common to experience nausea, headache, dizziness, fatigue, or irregular bleeding. These are well-recognised morning after pill side effects and generally resolve without treatment.4
A specific point worth keeping in mind. Emergency contraception can delay your next period by a few days or, in some cases, by up to a week. This is a normal effect and does not indicate that the pill hasn't worked.4 However, if your period is more than seven days late, or noticeably lighter than usual, take a pregnancy test.
If you vomit within three hours of taking either pill, it may not have been absorbed properly. If this happens, contact a pharmacist or GP as soon as possible, as you may need to take another dose.
5. It's Worth Having Emergency Contraception at Home Before You Need It
Both ellaOne and Levonelle have a shelf life of several years, so buying in advance is a practical option rather than an unusual one.2 4 Since effectiveness is directly tied to how soon you take it, having a pill at home removes the most common source of delay - finding an open pharmacy, waiting for same-day delivery, or arranging a consultation under pressure.
You can order emergency contraception online through Pharmica with a short consultation, without a GP appointment, and have it delivered for next-day use. Preparing in advance means that if you ever need it, acting quickly is straightforward.
If you do keep a pill at home, check the expiry date periodically and replace it when needed. And as with any use of emergency contraception, if you find yourself relying on it regularly, speak to a pharmacist or GP about a longer-term contraceptive method.
Frequently Asked Questions
How effective is the morning after pill?
Both pills are most effective when taken as early as possible. Levonelle is up to 95% effective within 24 hours of unprotected sex, falling to around 85% between 25 and 48 hours, and 58% between 49 and 72 hours.1 ellaOne is considered more effective later in its window and remains suitable for up to 120 hours.2 No morning after pill is 100% effective, and neither is a substitute for regular contraception.
How does the morning after pill work?
Both pills work primarily by delaying or preventing ovulation - the release of an egg - so that fertilisation cannot occur. They do not cause an abortion and have no effect if you are already pregnant.1 ellaOne (ulipristal acetate) works by blocking the action of progesterone to delay ovulation. Levonorgestrel works by mimicking a hormone that prevents the ovaries from releasing an egg.2
Can the morning after pill delay your period?
Yes. It is common for the morning after pill to shift your next period by a few days to a week, either earlier or later than expected.4 This is a normal hormonal effect and does not mean the pill has not worked. If your period is more than seven days late or significantly lighter than usual, take a pregnancy test.
Can I take the morning after pill more than once?
There is no medical reason you cannot take the morning after pill more than once, including within the same menstrual cycle. However, it is not designed to replace regular contraception and becomes less reliable with repeated use within a single cycle.1 If you are finding yourself using it frequently, speak to a pharmacist or GP about long-term contraceptive options.
References
- NHS. Levonelle and ellaOne (emergency contraception). Available at: nhs.uk
- Electronic Medicines Compendium (eMC). Zentiva Ulipristal 30mg — Summary of Product Characteristics. Available at: medicines.org.uk/emc
- College of Sexual and Reproductive Healthcare (COSRH). Emergency Contraception guideline. Available at: cosrh.org
- Electronic Medicines Compendium (eMC). Levonelle 1500 micrograms tablet — Summary of Product Characteristics. Available at: medicines.org.uk/emc
This article is intended for informational purposes only and does not replace professional medical advice. Always read the patient information leaflet supplied with your medication and speak to a healthcare professional if you have specific concerns.