Drinking alcohol increases the chances of having unprotected sex, according to new research.
Experts found that for every slight increase in alcohol consumption, a person's willingness to engage in risky sex got stronger.
Canadian researchers looked at 12 studies that examined the link between people's blood alcohol content (BAC) and how likely they were to say they would use a condom during intercourse.
After pooling the results, they found alcohol consumption affects decision-making, and this impact rises with the amount of alcohol consumed.
Every increase in blood alcohol level of 0.1 mg/ml led to a 5 per cent increase in the intention to engage in unprotected sex.
"Drinking has a causal effect on the likelihood to engage in unsafe sex, and thus should be included as a major factor in preventive efforts for HIV, says Dr Jurgen Rehm, lead author on the study.
"This result also helps explain why people at risk often show this behaviour despite better knowledge: alcohol is influencing their decision processes."