The ingredient in Benadryl that causes drowsiness is diphenhydramine. Commonly used as an antihistamine to treat allergies, diphenhydramine is also used as a sleep aid. Diphenhydramine is also classified as a CNS depressant, sedative and antiemetic.Continue Reading
Following oral administration, dependent on dosage, drowsiness and other common side effects normally last between 4 to 6 hours. The side effects of diphenhydramine, such as drowsiness, are worsened by the use of alcohol, sedatives and tranquilizers, as well as MAOIs, other CNS depressants and hypnotics. These effects are more pronounced in the elderly.
Some other notable side effects of diphenhydramine include agitation, confusion, fatigue, irritability, paresthesia, blurred vision and depression. In overdose, symptoms may include excitement, ataxia, tremor, sinus tachycardia, fever, hallucination, athetosis, convulsions, seizures, hypotension, deep coma, cardiorespiratory collapse and death.Learn more about Side Effects
The lethal dose of diphenhydramine, the generic name of Benadryl, varies significantly from person to person because of differences in weight and metabolism. There have been cases of people experiencing overdose symptoms with 500 milligrams of diphenhydramine and some cases where overdose is as high as 2,800 milligrams.Full Answer >
Potential side effects of diphenhydramine include dizziness; drowsiness; nausea; vomiting; and dry mouth, nose and throat, states MedlinePlus. Constipation, headache, nervousness, muscle weakness and increased chest congestion are other side effects, and excitement may also occur, specifically in children. Reporting any severe or persistent side effects to a doctor is recommended.Full Answer >
Potential side effects of taking diphenhydramine hydrochloride 25 mg include drowsiness, irritability, paresthesia, disturbed coordination and agitation, according to the U.S. National Highway Traffic Safety Administration. Blurred vision, constipation, dry mouth and upset stomach are additional side effects, advises WebMD.Full Answer >
Patients frequently report side effects related to the nervous system, such as sedation, drowsiness and depression, after using diphenhydramine hydrochloride, states Drugs.com. Other dangers include dystonic reactions, delirium and hypersensitivity, such as eczema, pruritus and rash.Full Answer >