Six years after the “Benadryl challenge” first appeared on TikTok, doctors are once again warning parents and teens about the deadly phenomenon re-emerging on social media. The challenge provokes people to purposely take too much Benadryl and fight the drowsy side effects that come with it, which will produce a high. Benadryl contains the active ingredient diphenhydramine, which is an antihistamine. When used properly, the drug is meant to relieve symptoms of seasonal or situational allergies or the common cold, such as a runny nose or sneezing. Consuming too much Benadryl also has a lot of medical side effects, such as high heart rate, urinary retention that can cause kidney dysfunction, and arrhythmia, or an irregular heartbeat. One case saw a 14-year-old female who had a seizure after participating in the Benadryl challenge. Dr.…