College students who drink alcohol before going out to a bar, club or sporting event are more likely than their peers who don’t “pre-drink” to experience blackouts, hangovers, alcohol poisoning or absence from work or school, a new study finds.

Pre-drinking also leads to an increased risk of unprotected sex and unplanned drug use or injury, according to the Los Angeles Times.

“Changing the location during a night increases the overall amount of alcohol consumption,” lead researcher Florian Labhart said in a news release. “It’s important that young people count the number of drinks they have during a night and to remember how many drinks they had already when they reach a new drinking location.”

The researchers studied the drinking habits of more than 250 Swiss students for five weeks. They found when students drank before going to a club or bar, they consumed more than they would normally. Students engaged in pre-drinking had an average of seven drinks, compared with just over four drinks for those who drank only at a bar or event.

Students who drank before going out had a 24 percent chance of experiencing negative consequences, compared with 18 percent for those who did not pre-drink.

The study appears in Alcoholism: Clinical & Experimental Research.