If you need emergency contraception, ella gives you more room than most. Its active ingredient, ulipristal acetate, can be taken up to five days after unprotected sex, and across that window it has been shown to work more effectively than the older levonorgestrel option, particularly in the later days.

It works by delaying ovulation, the release of an egg, which is the point at which pregnancy can otherwise occur. A single tablet is all it takes. As with any emergency contraception, the sooner it is used the better it performs, so it is worth acting promptly rather than waiting.

• Effective for up to five days after unprotected sex
• More effective than levonorgestrel later in that window
• A single tablet, taken as soon as you can

This is for emergencies, not regular contraception, and it does not protect against sexually transmitted infections. It is taken as a one off when needed.

Take the single tablet as soon as possible after unprotected sex, at any point up to five days; the sooner the better. If you are sick within three hours, take another tablet. It can be taken with or without food.

Ulipristal acetate 30 mg, the active ingredient.

Headache, nausea, abdominal discomfort, painful periods, tiredness and dizziness can follow, and the next period may arrive earlier or later than usual. Effects are short lived.

For emergency use only, not regular contraception, and it gives no protection against sexually transmitted infections. It will not work if you are already pregnant. Regular hormonal contraception started afterward may need extra precautions for a few days.