Truvada (tenofovir/emtricitabine) as pre-exposure prophylaxis (PrEP) against HIV has comparable safety to aspirin, at least for the short- and medium-term. Publishing their findings in Open Forum Infectious Diseases, researchers compared safety data from the five major PrEP studies to data from two major aspirin safety studies, looking at the relative numbers needed to harm (NNH, or the numbers of individuals needed to take the drug to yield a specific safety outcome in one of them) between PrEP and aspirin.

Among men who have sex with men (MSM) and transgender women taking PrEP, the NNH was 114 for nausea and 96 for unintentional weight loss. Among heterosexuals, PrEP’s NNH was 68 for moderate decreased absolute neutrophil count (infection-fighting white blood cells). Participants in the PrEP trials reported no serious irreversible health problems and no hospitalizations or deaths associated with Truvada.

PrEP was associated with a mild decrease in creatinine clearance, which is an indicator of kidney function, as well as a small decrease in bone mineral density. Both of these changes reversed after individuals stopped taking Truvada. The drug has not been associated with any bone fractures, pregnancy problems or permanent kidney failure.

For aspirin, the NNH was 909 for major gastrointestinal bleeding, 123 for any gastrointestinal bleeding and 15 for any bleeding problems in men. For women, aspirin’s NNH for easy bruising was 10.

The researchers concluded that PrEP has a favorable safety profile compared to aspirin. Studies are still needed, however, to assess the long-term safety of PrEP.

To read the study abstract, click here.