What is DoxyPEP? 

With DoxyPEP, the antibiotic doxycycline is taken after sex to prevent syphilis and chlamydia infection. Studies have shown efficacy with a single 200 mg dose of doxycycline taken 24 hours after sex. Never take more than 200 mg per 24 hours.

Its effectiveness has been proven for cis men, trans women and other people who were assigned male at birth and have sex with cis men. There are no studies that have demonstrated efficacy for cis women, trans men and other individuals assigned female at birth.

What does DoxyPEP protect against? 

The data on efficacy and epidemiological impact is still relatively limited. Studies tend to indicate that taking the antibiotic doxycycline after sex could prevent infections with chlamydia and syphilis. With other bacterial STIs, and particularly gonorrhoea, however, the effectiveness is lower or non-existent. Very important: doxycycline does not prevent viral infections such as HIV, hepatitis B, herpes or HPV.

What side effects are there?

• Its use leads to a considerable sensitivity to light: constant UV protection is required.
• Its use contributes to the development of antibiotic resistance in STIs (particularly gonorrhoea) and other microorganisms, including some that are transmitted during sex.
• Its use affects the microbiome and the extent of the possible consequences is not yet known (e.g. digestive disorders, high cholesterol levels, diabetes).
• Weight gain may occur with prolonged use.

What should I keep in mind?

DoxyPEP is not recommended in Switzerland, in particular because of the risks to public health. If you are taking doxycycline, we recommend:

• Openly discuss self-medication with a healthcare professional or contact a sexual health centre.
• Safer Sex: HIV protection strategy and STI test every three months in the event of an STI diagnosis: check efficacy and resistance