Most people who take PrEP do not experience side effects, but some people do, especially in the first days or weeks after starting. About 1 out of every 5 people experience some side effects after starting PrEP. The most common are headache and gastrointestinal distress (nausea, gas or bloating, or abdominal pain). Some people also experience sleep disturbances, including unusually vivid dreams. For almost everyone, these side effects occur only when starting PrEP and last only a few days or, less commonly, a few weeks.

Weight gain is not associated with Truvada as PrEP, but a small percentage of people do experience minor weight loss.

Truvada as PrEP does not cause liver problems.

Over the first 6 months of taking Truvada for PrEP, many people experience a slight decrease in bone mineral density (in the range of ½% to 1-½%). This change is not clinically significant, meaning it does not lead to fractures or other problems in people who had normal bone density to begin with.

Over the longer term, a very small number of people (about 1 in 200) experience some change in kidney function. Your kidney function will be assessed by your health care provider before prescribing PrEP and periodically monitored for so long as you are on PrEP. For a very small percentage of people, a change in kidney function may lead your health care provider to recommend you stop taking PrEP. In almost all cases, after stopping PrEP, kidney function returns to normal. Again, changes in kidney function are rare in people on PrEP, but occur most often in patients who are older than 40, have diabetes or hypertension, or take other medications that are processed by the kidneys.