The Food and Drug Administration is warning people not to take up the so-called "Benadryl Challenge" that has gone viral on TikTok, saying that overdosing on the antihistamine can be fatal.
FDA deputy secretary-general Supattra Boonserm said on Tuesday that an overdose of diphenhydramine, sold under the brand name Benadryl, could cause fast and irregular heart beats, hypertension and a heart attack.
She was responding to international reports of casualties among young people who took up the "Benadryl Challenge" by taking large quantities of the drug to induce hallucinations.
Ms Supattra said the antihistamine was used to treat respiratory allergies and cold symptoms like runny nose and sneezing.
A child could take 6.26-12.6 milligrammes (0.5-1 teaspoon) every 4-6 hours while the safe dosage for an adult was set at 25-60 mg (1-2 capsules) during that time.