Those who suffer from alcohol use disorder can experience severe withdrawal symptoms once they stop drinking, including shakes, anxiety, depression, insomnia, and heightened cravings. This combination of physical and psychological withdrawal symptoms makes it incredibly challenging to quit drinking, but a drug originally designed to treat high blood pressure may help alcoholics in their life’s battle with addiction.

In a new double-blind study published in the American Journal of Psychiatry, researchers at Yale University gave the drug prazosin or a placebo to 100 participants who were diagnosed with alcohol use disorder and had entered outpatient treatment. Prior to receiving treatment, all patients had experienced varying degrees of withdrawal symptoms.

But those who took prazosin, a substance that belongs to a class of medications called alpha-blockers, significantly reduced the number of heavy drinking episodes and days they consumed alcohol compared to those who received just a placebo. Those who experienced very little or no withdrawal symptoms saw little improvements from prazosin.

“There has been no treatment readily available for people who experience severe withdrawal symptoms and these are the people at highest risk of relapse and are most likely to end up in hospital emergency rooms,” said corresponding author Rajita Sinha, the Foundations Fund Professor of Psychiatry, a professor of neuroscience, and director of the Yale Stress Center.

Prazosin has been used for years to treat high blood pressure and prostate problems in men, among other conditions. According to previous studies that investigated the body’s reaction to prazosin, the drug acts on stress centers in the brain, improves working memory, and curbs anxiety and cravings.

When an alcoholic suddenly stops drinking, stress centers in the brain start to flare up. The more severe the withdrawal symptoms and the higher the cravings, the higher the disruption in the stress centers. But the activation of the stress centers diminishes the longer a person with alcohol use disorder stays away from drinking.

Prazosin may help ease this transition and increase the odds that a patient stays sober. Alcohol use disorder is an issue that affects 17 million U.S. adults and 855,000 youths ages 12 to 17, according to the National Institutes of Health. Most people who want to quit, however, find it difficult to do it completely on their own, especially if they lack coverage.

The only major drawback is that treatment with prazosin for alcohol withdrawal needs to be administered three times daily to be effective, the researchers said. On the upside, this is a drug that has been in use for years in a clinical setting, so it is safe.