Emergency contraception: levonorgestrel vs ulipristal

If you have had unprotected sex, or your usual contraception has failed, emergency contraception can still prevent a pregnancy. It works best the sooner it is used, so it is worth acting quickly rather than waiting.

There are two morning-after pills and they are not interchangeable. This article explains which is which, and when each is the right choice. No judgement, no assumptions.

The two morning-after pills

Levonorgestrel, a 1.5 mg tablet, is licensed for use up to 72 hours, three days, after unprotected sex. It works mainly by delaying ovulation, so it is only effective if you have not yet ovulated in that cycle.

Ulipristal acetate, a 30 mg tablet, is licensed for use up to 120 hours, five days, after unprotected sex. It also works by delaying ovulation, but it can do so slightly later in the cycle than levonorgestrel, which makes it the more effective of the two for many people, particularly closer to ovulation.

Both are available on prescription, and the doctor will make sure you get the one that fits your situation and timing rather than whatever happens to be nearest to hand.

How to choose between them

As a general rule, ulipristal is the more effective oral option, especially if it has been more than 72 hours or if you are around the most fertile part of your cycle. Levonorgestrel still has a place, for example if ulipristal is not suitable. The doctor will weigh up the timing, where you are in your cycle, your weight, and any other medication you take.

Weight matters for levonorgestrel: it becomes less effective at a higher body weight, so a double dose is recommended above around 70 kg or a body mass index over 26. Ulipristal is less affected by weight.

No oral emergency contraception is 100 percent effective, which is another reason to act early and to do a pregnancy test if your next period is more than a few days late or much lighter than usual.

What to expect after taking it

Most people have no more than mild effects from the morning-after pill. Some feel a little nauseous, and your next period may come a few days earlier or later than usual. If you are sick within two to three hours of taking it, the dose may not have been absorbed and you may need to repeat it, so let us know. Certain medicines that speed up the liver, such as some epilepsy treatments, can reduce how well the morning-after pill works, in which case a copper coil or a higher dose may be the better option.

The most effective option of all

The single most effective emergency contraceptive is not a pill at all. A copper coil, fitted up to five days after unprotected sex, is more than 99 percent effective and then keeps working as ongoing contraception. We do not fit coils at LoveMyLife at launch, but NHS sexual health services and most GP surgeries fit them free, often at short notice for emergency use. If you can access one in time, it is worth considering.

Starting ongoing contraception afterwards

Emergency contraception is a one-off. It does not protect you for the rest of the cycle, so if you are not on a regular method this is a good moment to start one. After levonorgestrel you can begin a hormonal method straight away and use condoms for a short period. After ulipristal you should wait five days before starting hormonal contraception, because starting sooner can stop the ulipristal working, and use condoms in the meantime. The doctor will give you the exact plan.

Breastfeeding

Levonorgestrel is fine while breastfeeding. With ulipristal, the advice is to express and discard your milk for one week after taking it. If you are breastfeeding, mention it so we choose accordingly.

When emergency contraception is not the answer

If your period is already late and there is any chance you are pregnant, a morning-after pill will not end an existing pregnancy, and a pregnancy test is the first step. If you find yourself needing emergency contraception repeatedly, that is a sign your regular method is not working for you, and it is worth a proper conversation about something that fits your life better. And if the sex was not something you consented to, support is available and we can help you find it.

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