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First Aid for Diphenhydramine Overdose

Last updated Feb. 26, 2018

Approved by: Maulik P. Purohit MD, MPH

Diphenhydramine is an antihistamine that relieves allergy and insomnia. Diphenhydramine Overdose is the accidental or intentional intake of the drug in dosage higher than the prescribed values.

What is Diphenhydramine Overdose?

  • Diphenhydramine is an antihistamine that relieves allergy and insomnia
  • Diphenhydramine Overdose is the accidental or intentional intake of the drug in dosage higher than the prescribed values
  • The condition is diagnosed based upon the clinical history, combination of signs and symptoms, and additional tests (that may include, in some cases, radiological studies and laboratory tests)

Diphenhydramine Overdose may be also referred to as the following:

  • Benadryl Overdose
  • Nytol Overdose
  • Sominex Overdose

What are the Causes of Diphenhydramine Overdose?

  • Diphenhydramine Overdose is caused by the intake of diphenhydramine containing drug in dosage higher than normally prescribed
  • This intake could be accidental, or in some cases intentional, to bring self-harm
  • The drug may be sold as Tylenol PM, Benadryl, Nytol and Sominex among others

Note: The drug can interact with other prescribed or non-prescribed medications in the body. Such interactions may enhance the therapeutic effects of the drug or other medications being taken, resulting in undesired side effects (such as an overdose).

What are the Signs and Symptoms of Diphenhydramine Overdose?

The signs and symptoms of Diphenhydramine Overdose can vary from one individual to another. It may be mild in some and severe in others. Several systems of the body, such as the digestive system, nervous system, vascular system, respiratory system, skin and ENT may be affected.

The signs and symptoms of Diphenhydramine Overdose include:

  • Intense drowsiness, restlessness, nausea
  • Hallucinations, delirium, anxiety
  • Difficulty speaking
  • Increased heart rate
  • Lack of muscle coordination; difficulty walking
  • Dry mouth and eyes
  • Impaired memory
  • Flushed and dry skin
  • Urination difficulties
  • Blurry vision; dilated pupils
  • Ringing in the ears
  • Seizures

How is First Aid administered for Diphenhydramine Overdose?

First Aid tips for Diphenhydramine Overdose:

  • Diphenhydramine Overdose is a life-threatening condition. If an individual is suspected to have overdosed on imipramine, call 911 (or your local emergency number) for emergency assistance immediately
  • Call the Poison Control Center at 1-800-222-1222 (or your local poison control center) for further instructions
  • Determine the amount and type of drug taken, time of consumption, patient’s age, weight, and general health status
  • Confirm that the airways are protected; also, ensure breathing and the presence of pulse
  • Take individual to emergency room for further treatment
  • Always try to take the medication strip/bottle/container to the ER

The emergency medical health professional might take the following steps towards treating the overdose:

  • Gastric lavage for elimination of drug from the stomach
  • Administer activated charcoal to avoid absorption in body
  • Medically manage serious symptoms, such as reduced heart rate and breathing difficulty
  • Also, relieve respiratory distress with an artificial respirator
  • Administer laxatives for elimination of drug from the body
  • Administer fluids by an intravenous drip line

Who should administer First Aid for Diphenhydramine Overdose?

First aid for Diphenhydramine Overdose is administered by healthcare professionals. 

  • The individual who overdosed, or someone near, should call 911 for emergency assistance (or the local emergency number)
  • They should also call the poison control center at 1-800-222-1222 (or the local poison control center) and follow instructions

What is the Prognosis of Diphenhydramine Overdose?

  • Diphenhydramine Overdose can be a life-threatening condition, due to delirious behavior caused by hallucinations, as well has increased heart rate and respiratory disturbances
  • Nevertheless, the prognosis depends on the type and amount of drug intake, time from overdose to treatment, and general health status of the affected individual (who overdosed)
  • If the individual survives the first 24 hours after overdose, the prognosis is usually good
  • In case of complications including pneumonia or unconsciousness, it may considerably worsen the outcome. Damage to the brain may become irreversible, if timely oxygen therapy is not administered

In general, overdoses are common situations in the emergency departments. A majority of the cases are often not fatal, when appropriate treatment is given.

How can Diphenhydramine Overdose be Prevented?

Diphenhydramine overdose can be prevented by:

  • Taking the right dose of medication at recommended times
  • Exercising caution while taking multiple drugs that contain diphenhydramine
  • Avoiding drugs that might interact with diphenhydramine
  • Talking to your healthcare provider, if recommended dose of diphenhydramine is not helpful, you tend to fall asleep, or the drug does not relieve allergy symptoms
  • Refrain from self-medication
  • Keep medications out of reach of children in child-proof containers
  • For older individuals and those who tend to be forgetful, medications should be stored in single dose containers with time labels, to avoid multiple dosage
  • Monitor intake of this drug especially in patients, who have depression or harbor suicidal thoughts and behavior

It is important to give your healthcare provider a complete list of prescription and non-prescription medications that are being currently taken. This will help them in assessing the possible drug interactions within various medications and help avoid/prevent accidental or unintentional toxic drug effects.

What are certain Crucial Steps to be followed?

  • Call 911 (or your local emergency number) for emergency assistance, if symptoms are life-threatening
  • Call Poison Control Center at 1-800-222-1222 (or the local poison control center) and follow the recommend steps
  • It would be helpful if the following information is readily available:
    • Type, dosage and time of administration of medication
    • Age and weight of the individual
    • And, the overall health status of the individual

What are some Useful Resources for Additional Information?

References and Information Sources used for the Article:

Helpful Peer-Reviewed Medical Articles:

Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: July 7, 2017
Last updated: Feb. 26, 2018