Patients taking PrEP should be informed of TD*/FTC side-effects experienced by participants in PrEP trials. These include headache, nausea, flatulence and the potential for renal injury. Hepatotoxicity can occur but it is very uncommon. In these trials, side-effects were uncommon and usually resolved within the first month of taking PrEP (known as ‘start-up syndrome’). Clinicians should discuss the use of over-the-counter medications for headache, nausea and flatulence should they occur. Patients should also be counselled about symptoms that indicate a need for urgent evaluation (e.g. those suggesting possible acute renal injury or acute HIV infection). See Clinical assessment before starting PrEP for a review of the signs and symptoms of acute HIV infection.