But it depends on the size of that one drink and how much alcohol
A "beverage alcohol equivalent" is equal to one 12 ounce beer, 4 ounces of wine or one ounce of whiskey or hard liquor. For most people, having one drink per night isn't harmful. Some studies suggest that there is actually a benefit to one drink per night, especially red wine due to the antioxidants. Check with your dr.