A U.S. study says women who have more than five alcoholic drinks at one sitting are at increased risk of having unsafe sex and contracting sexually transmitted diseases.

Researchers at John Hopkins University medical school in Baltimore looked at the correlation between binge drinking and risky sexual behaviours in women. They interviewed patients at an urban clinic for sexually transmitted infections to explore the link.

In their study, which will be published in the November issue of the journal Alcoholism: Clinical and Experimental Research, the researchers found that women who binge drink are at increased risk of practising unsafe sex, including having multiple partners and engaging in anal sex, leading to high rates of gonorrhea.

"The link between binge drinking and risky sexual behaviour is complex," said Heidi Hutton, assistant professor of psychiatry and behavioural sciences at the medical school and an author of the study.

"We wanted to examine one component of that relationship, whether binge drinking increased the risk of engaging in sexual behaviours and having STDs. We found ... that binge drinking increased STD risk for women."

Binge drinking was defined as having more than five drinks at one time.

Not surprising

Geetanjali Chander, assistant professor of medicine in the general internal medicine division at the school, said the results are not entirely surprising.

"Binge drinking results in a decreased ability to make clear decisions and can enable individuals to engage in behaviours that they would not if sober," she said.

"Initially, some individuals may drink with the expectation of decreasing inhibitions, or some may drink because they are anxious or depressed, and they expect alcohol to alleviate their symptoms. Regardless of why they choose to drink, many people do not perceive the potential risk or harm that may result from binge drinking."

The researchers asked 795 patients who were being evaluated or treated at the urban clinic for sexually transmitted infections whether they would be interested in being interviewed. Of that number, 671 agreed to answer questions about their recent alcohol and drug use and risky sexual behaviours.

The respondents included 322 men and 349 women, though the research focused on the women. Ninety-five per cent of the respondents were African-American. Their answers were analyzed to examine the link between binge drinking, sexual behaviours and sexually transmitted infections.

The researchers also took into consideration the age, employment and drug use of the respondents.

Hutton said the results are worthy of further study and she recommends that staff at STD clinics routinely screen for binge drinking.

"While it is standard practice in most STD clinics to discuss behavioural factors for STD risk, binge drinkers may be harder to identify than alcohol-dependent individuals because the latter have more obvious impairment of function."