Levonelle

Levonelle is an emergency contraceptive pill containing 1.5 mg of levonorgestrel, a synthetic version of the progestogen hormone your ovaries naturally produce. It works mainly by delaying or preventing the release of an egg from the ovary (ovulation). If sperm are already in the body when you take it, the idea is that ovulation is held back long enough for the sperm to die before an egg is released. It's important to understand what it doesn't do: it can't reverse a pregnancy that has already started, and it's not a regular contraceptive.

Levonelle is licensed for use up to 72 hours (three days) after unprotected sex, but the sooner you take it, the better it works. Effectiveness drops noticeably with each passing day. If more than 72 hours have passed, Levonelle is no longer the right option — ellaOne (which works up to 120 hours) or a copper coil (which is the most effective emergency contraception of all, and can be fitted up to five days after sex or up to five days after the earliest expected ovulation) becomes the better choice.

Effectiveness depends heavily on timing and where you are in your cycle. Taken within 24 hours, it can prevent the majority of pregnancies that would otherwise have occurred from that episode of unprotected sex. By 48 to 72 hours, that figure drops considerably. To put it in perspective, the copper coil prevents more than 99% of pregnancies when used as emergency contraception, which is why it remains the gold standard if it's available to you.

Probably not. Because Levonelle's main mechanism is to delay ovulation, it doesn't work once an egg has already been released. This is one of the key reasons it can fail — and why timing within your cycle matters as much as timing after sex. If you know roughly when you ovulate and unprotected sex happened around or just after that point, ellaOne or a copper coil are usually better options.

There's evidence that Levonelle becomes less reliable in women with a higher body weight or BMI. UK guidance suggests that women weighing over 70 kg or with a BMI over 26 may benefit from a double dose (3 mg) of levonorgestrel — or, often preferably, from ellaOne or a copper coil instead. A pharmacist or prescriber will weigh this up when you're seen.

If you're sick within three hours of taking Levonelle, the dose may not have been absorbed properly. You'll usually need to take another tablet as soon as possible. After three hours, the pill has generally been absorbed and a repeat dose isn't needed. Persistent nausea and vomiting are worth flagging because they can occasionally signal something else going on.

Most women tolerate it well. The most commonly reported effects are nausea, headache, tiredness, lower abdominal cramps, breast tenderness, dizziness, and changes to your next period — which might come earlier or later than expected, and may be heavier, lighter, or more uncomfortable than usual. These effects are short-lived. Severe lower abdominal pain a few weeks after taking it should always be assessed, because in rare cases it can be a sign of an ectopic pregnancy that needs urgent medical attention.

Most women find that their period arrives within a week of when they would have expected it. It can come earlier or up to a week later. If your period is more than seven days late, lighter than usual, or unusually short, take a pregnancy test. It's also worth testing if you have any concerns at all — the test is the only reliable way to rule out pregnancy after emergency contraception.

Yes. Unlike regular contraception, there's no medical limit on how many times you can take Levonelle in a single cycle if you genuinely need it. That said, repeated use suggests your usual contraception isn't working for you, and a conversation about more reliable options — such as the implant, coil, or combined pill — is well worth having.

Yes. Some medicines speed up the way the liver breaks down levonorgestrel, which lowers the level circulating in your blood. The main culprits are enzyme-inducing drugs such as rifampicin, certain epilepsy medicines (carbamazepine, phenytoin, primidone, phenobarbital), some HIV treatments, and the herbal remedy St John's Wort. If you've taken any of these in the past 28 days, Levonelle may not be effective even at a double dose, and you'll usually be advised to consider a copper coil or, in some cases, ellaOne as an alternative.

Yes. After taking Levonelle, you can resume your usual hormonal contraception (pill, patch, ring) straight away, but you'll need to use condoms or another barrier method for the next seven days (or nine days for the qlaira/Zoely-type pills) until the regular method is fully reliable again. This is one of the practical advantages of Levonelle over ellaOne, which requires a longer wait before restarting hormonal contraception.

No. Levonelle only addresses the episode of unprotected sex it was taken for. It doesn't provide ongoing protection, so any further unprotected sex in the same cycle could still lead to pregnancy. Use condoms or another reliable method for the rest of the cycle.

No. Emergency contraception only addresses pregnancy risk. If there's any concern about exposure to STIs, including HIV, it's worth booking a sexual health check. Some clinics will also discuss HIV post-exposure prophylaxis (PEP) if the unprotected sex carried a meaningful HIV risk and was within the last 72 hours.