PrEP and side effects

Most people taking PrEP do not get side effects. 

However, like all medicines, some people might get some side effects.

Less than 1 in 10 people report mild nausea, diarrhoea, bloating and headache in the first month. These side effects then usually stop.

Taking oral PrEP with food can sometimes help.

It is also okay to separate the first double dose by a few hours, if this helps.

Occasionally, PrEP can cause more serious side effects that reduce kidney function and/or bone health. This is why kidney tests are needed when using oral TD/FTC. 

Changes in bone structure are usually small and reverse after stopping TD/FTC. This is similar to a commonly used oral contraceptive but might be important if you are younger than 18 when bones are still developing. Bone strength was not fully reversed after a year in one study in adolescents aged 15 to 19.

PrEP does not increase the risk of bone fractures.

The main side effects with injectable PrEP are linked to the injections. This can sometimes be sore or leave a bump under the skin which takes a while to go down. Very few people in studies stopped PrEP for this reason.

Last updated: 1 October 2025.