US health officials have told some people they should proactively take an antibiotic after sex to prevent sexually transmitted infections. The Centers for Disease Control and Prevention finalised guidance this week for potentially higher-risk groups on taking doxycycline to reduce infection rates of chlamydia, syphilis and gonorrhoea. The guidelines apply to men who have sex with men and transgender women who have had at least one STI in the past year. The guidance was proposed in October 2023 based on clinical trial data that showed taking a 200mg dose after unprotected sex cut chlamydia and syphilis infections by more than 70 per cent and gonorrhoea infections by half. The UK’s Health Security Agency has also raised concerns over an increase in STIs in 2023, including the highest number of syphilis infections since 1948. The Local Government Association responded that a 10-year sexual health strategy was needed to prevent and treat infections.