PrEP only combats HIV and doesn’t protect against other STIs like gonorrhea, chlamydia, and syphilis. Typically, HIV-prevention patients return to their doctors every three months to get tested for all STIs, along with a basic blood profile that includes indicators of kidney health. Hendrix says because Truvada and Descovy are prophylactics, patients should take their pills every day to stay protected. From the studies he’s read, the only instances in which a person receiving PrEP eventually contracted HIV were due to them failing to take the daily pill. However, U.S. doctors and clinics have recently accepted an on-demand “2-1-1” dosage option, where patients take two pills the day before sex and one pill each day for two days after—in most cases, it’s just as effective as the daily pill.