The emergency contraceptive pill works quickly — but exactly how quickly depends on which type you take and how soon after unprotected sex it is used. Both main options available in the UK, levonorgestrel (such as Levonelle) and ulipristal acetate (ellaOne), begin working as soon as they are taken, primarily by delaying or preventing ovulation before fertilisation can occur. Levonorgestrel is most effective when taken within 72 hours of unprotected sex, while ellaOne can be used up to 120 hours (five days) afterwards and maintains its effectiveness more consistently across that window. Time is absolutely critical — the sooner you take the emergency contraceptive pill, the more effective it is likely to be. At G.M. Graham Pharmacies in Essex, we provide fast, confidential access to emergency contraception with no appointment needed, so you can get the help you need without delay.
Book a consultation now for fast, discreet access to the emergency contraceptive pill and expert advice tailored to your situation.
Key takeaways
- The emergency contraceptive pill works by delaying or preventing ovulation — it does not terminate an existing pregnancy.
- Levonorgestrel (e.g. Levonelle) must be taken within 72 hours of unprotected sex and is most effective the sooner it is taken — effectiveness decreases over time.
- Ulipristal acetate (ellaOne) can be taken up to 120 hours (five days) after unprotected sex and maintains effectiveness more consistently across that window.
- Neither pill is 100% effective — ellaOne is generally considered slightly more effective than levonorgestrel, particularly between 72 and 120 hours.
- Body weight may affect the effectiveness of levonorgestrel — current FSRH guidance recommends ellaOne or a copper IUD as more effective alternatives where this is a concern. Speak to a pharmacist for personalised advice.
- The copper IUD is the most effective form of emergency contraception available and can be fitted up to five days after unprotected sex.
What is the Emergency Contraceptive Pill?
The emergency contraceptive pill — often referred to as the “morning after pill” — is a form of hormonal contraception used after unprotected sex or contraceptive failure to reduce the risk of unintended pregnancy. It is important to understand that it is not the same as the abortion pill and does not end an established pregnancy. Instead, it works by interfering with the ovulation process, either delaying or preventing the release of an egg so that fertilisation cannot take place.
There are two types of emergency contraceptive pill widely available in the UK. Levonorgestrel is a synthetic progestogen that works primarily by delaying ovulation. Ulipristal acetate (ellaOne) is a selective progesterone receptor modulator that inhibits or delays ovulation and may also affect the lining of the uterus. Both are available from pharmacies across the UK, including G.M. Graham Pharmacies in Essex, without a prescription.
How Quickly Does Each Emergency Contraceptive Pill Work?
Both types of emergency contraceptive pill begin working as soon as they are absorbed into the bloodstream, which typically happens within a few hours of taking them. However, “working” in this context means initiating the hormonal process that delays ovulation — not an instant barrier to pregnancy. This is why timing is so important.
Levonorgestrel is most effective when taken as soon as possible after unprotected sex — effectiveness decreases with time and precise rates vary between studies, but the evidence consistently shows that acting quickly gives you the best possible chance of it working. After 72 hours it is not licensed for use. It is taken as a single dose.
EllaOne (ulipristal acetate) is taken as a single 30mg tablet and can be used up to 120 hours after unprotected sex. Crucially, research suggests its effectiveness does not decline as steeply over time as levonorgestrel — making it a more reliable option if more than 24 hours have passed since unprotected sex. It is also considered more effective for people with a higher body weight.
Does Body Weight Affect How Well the Emergency Contraceptive Pill Works?
This is an important and often overlooked consideration. Current FSRH guidance advises that body weight may reduce the effectiveness of levonorgestrel, and recommends that ellaOne or a copper IUD should be considered as more effective alternatives for people where this is a concern. There is no single fixed weight or BMI threshold — the most appropriate option depends on your individual circumstances, which is why speaking to a pharmacist or clinician for personalised advice is always the best course of action. For those with a very high BMI, a copper IUD offers the most reliable protection regardless of body weight.
This does not mean levonorgestrel is completely ineffective at higher body weights — it may still provide some protection — but the risk of reduced efficacy means it is always worth discussing your individual circumstances with a pharmacist or clinician. Our team at G.M. Graham Pharmacies can advise you on the most appropriate option based on your specific situation. Contact us to book a confidential consultation today and get expert, personalised advice on the most effective emergency contraception for you.
What to Expect After Taking the Emergency Contraceptive Pill
After taking the emergency contraceptive pill, most people do not experience significant side effects, though some may notice nausea, headache, breast tenderness, or abdominal discomfort. If vomiting occurs within two hours of taking levonorgestrel, or within three hours of taking ellaOne, you should seek advice from a pharmacist as you may need to take another dose.
Your next period may arrive earlier or later than expected — this is a normal response to the hormonal shift caused by the pill. If your period is more than five to seven days late, or if it is unusually light, it is worth taking a pregnancy test to confirm the emergency contraception has worked. The emergency contraceptive pill does not provide ongoing contraceptive cover, so it is important to use a reliable method of contraception going forward.
If you have taken ellaOne, you should not use hormonal contraception such as the combined pill, mini pill, or contraceptive patch for at least five days after taking it, as this can reduce its effectiveness. Your pharmacist can advise on when it is safe to resume your regular contraception. To get fast, confidential advice on next steps after taking emergency contraception, our team at G.M. Graham Pharmacies is here to help. Get in touch with us today for fast, confidential advice on your next steps and ongoing contraception options.
Frequently Asked Questions
Whether you are unsure about timing, effectiveness, or what to expect after taking it, we have answered the most common questions about the emergency contraceptive pill below.
Can I get the emergency contraceptive pill from a pharmacy without a prescription?
Levonorgestrel (such as Levonelle) is available to buy over the counter from a pharmacy without a prescription for people aged 16 and over. EllaOne (ulipristal acetate) is also available from pharmacies, though in some settings it may require a brief consultation with a pharmacist before it is supplied.
How effective is the emergency contraceptive pill?
Levonorgestrel is most effective when taken as soon as possible after unprotected sex — effectiveness decreases with time and precise rates vary between studies, so acting quickly is essential. EllaOne maintains more consistent effectiveness across the full 120-hour window and is generally considered slightly more effective overall, particularly between 72 and 120 hours after unprotected sex.
Does the emergency contraceptive pill protect against STIs?
No — the emergency contraceptive pill only reduces the risk of unintended pregnancy and provides no protection against sexually transmitted infections (STIs). If you are concerned about potential STI exposure, you should seek advice from a sexual health clinic or your GP, who can arrange appropriate testing.
Can I take the emergency contraceptive pill more than once?
The emergency contraceptive pill can be taken more than once, but it is not intended as a regular method of contraception and is significantly less reliable than ongoing methods such as the pill, implant, or coil. If you find yourself needing emergency contraception frequently, it is a good idea to speak to a healthcare professional about finding a long-term contraceptive method that suits your lifestyle.
Will the emergency contraceptive pill affect my regular contraception?
If you have taken ellaOne, you should avoid using hormonal contraception for at least five days afterwards, as it can reduce ellaOne’s effectiveness. Levonorgestrel does not interact with hormonal contraception in the same way, but your pharmacist will advise you on when it is appropriate to resume your regular method and whether additional precautions are needed.
Is the emergency contraceptive pill the same as the abortion pill?
No — the emergency contraceptive pill is not the same as the abortion pill and works in a completely different way. The emergency contraceptive pill prevents pregnancy from occurring by delaying or stopping ovulation, while the abortion pill (mifepristone and misoprostol) is used to end an existing pregnancy and is only available through specific medical services.
Getting the Emergency Contraception You Need
When it comes to emergency contraception, speed matters more than almost anything else. The sooner you act, the more options you have available and the more effective those options are likely to be. Whether you choose levonorgestrel or ellaOne, taking it as soon as possible after unprotected sex gives you the best possible chance of preventing an unintended pregnancy.
The emergency contraceptive pill is safe, widely available, and nothing to feel embarrassed about. Millions of people across the UK use it every year, and pharmacists are trained to provide it quickly, discreetly, and without judgment. If you are ever unsure which option is right for you, a quick conversation with a pharmacist can make all the difference.
At G.M. Graham Pharmacies in Essex, we offer fast, confidential access to both types of emergency contraceptive pill, as well as friendly expert advice to help you make the right choice for your situation. Nobody should have to struggle to access emergency contraception — our team is here, ready to help, with no appointment needed. Book a consultation with our team today.
Disclaimer: The information provided in this blog post is intended for general informational purposes only and does not constitute medical advice. Emergency contraception options vary depending on individual health circumstances, timing, and other factors. You should always consult a qualified pharmacist, GP, or sexual health professional before taking any medication, including the emergency contraceptive pill. If you have any concerns about your contraceptive options or sexual health, please seek professional medical advice promptly.
