There has been one reported case of lactic acidosis in a person taking Truvada as PrEP, but this case has not been confirmed or published. There have also been rare cases in people taking one of the drugs in Truvada for treatment of hepatitis B.

The US FDA-approved Truvada label and the EMA Summary of Product Characteristics both include warnings about lactic acidosis. EMA says lactic acidosis is rare and occurs more often in women (especially if overweight) and in people with pre-existing liver disease.

While lactic acidosis is serious, it is also exceptionally rare.