Studies have shown that PrEP is safe; however some people who take PrEP may experience side effects (though most do not). Headache, weight loss, nausea, vomiting, and abdominal discomfort are the most common side effects and these most often resolve with time (after a few weeks of taking PrEP).
In a very small number of people, PrEP can affect the kidneys. These issues usually go away after stopping PrEP. Whilst using PrEP, you will have regular kidney function tests, during your clinic check-ups.
You will need to be tested for HIV before starting PrEP. People with HIV should not take PrEP as it is not sufficient to treat HIV.