This article discusses the health effects from an overdose of diphenhydramine, a type of medicine called an antihistamine, which is found in various allergy and sleep medicines.
This is for information only and not for use in the treatment or management of an actual poison exposure. If you have an exposure, you should call your local emergency number (such as 911) or the National Poison Control Center at 1-800-222-1222.
Benadryl overdose; Sominex overdose; Nytol overdose
The ingredient diphenhydramine may be found in the following products:
- Tylenol PM
This list is not all-inclusive.
Agitation Blurred vision Coma Confusion
- Dry cotton-like mouth
- Flushing on the face and skin
- Inability to urinate
- Incoherence (not understandable)
- Lack of sweat
- Low grade fever
- Movement problems
- Rapid heart rate
Stomach pain Unsteadiness
Before Calling Emergency
Determine the following information:
- Patient’s age, weight, and condition (for example, is the person awake or alert?)
- Name of the product (ingredients and strengths, if known)
- Time it was swallowed
- Amount swallowed
However, do NOT delay calling for help if this information is not immediately available.
Poison Control, or a local emergency number
The National Poison Control Center (1-800-222-1222) can be called from anywhere in the United States. This national hotline number will let you talk to experts in poisoning. They will give you further instructions.
This is a free and confidential service. All local poison control centers in the United States use this national number. You should call if you have any questions about poisoning or poison prevention. It does NOT need to be an emergency. You can call for any reason, 24 hours a day, 7 days a week.
What to expect at the emergency room
The health care provider will measure and monitor the patient’s vital signs, including temperature, pulse, breathing rate, and blood pressure. Symptoms will be treated as appropriate. The patient may receive:
- Activated charcoal
- Breathing support
- Fluids through a vein (by IV)
- Tube through the mouth into the stomach to wash out the stomach (
Recovery is likely if the patient survives the first 24 hours.
Few patients actually die from an antihistamine overdose, unless there have been serious heart rhythm disturbances or breathing problems.