Question: how long do you have to wait to take benadryl after drinking?
Answer: Most studies report that the vast majority of diphenhydramine and associated metabolites, for most people, are excreted via the kidneys within 24—48 hours of a dose. Based on the above information, if you are looking to completely avoid alcohol while Benadryl is in your system, you need to wait 24 to 48 hours.