benadryl allergic reaction Benadryl dosage chart

How much benadryl do you take for an allergic reaction

A life-threatening allergic reaction (anaphylaxis) can cause shock, a sudden drop in blood pressure and trouble breathing. In people who have an allergy, anaphylaxis can occur minutes after exposure to a specific allergy-causing substance (allergen). In some cases, there may be a delayed reaction, or anaphylaxis may occur without an obvious trigger.

If you're with someone having an allergic reaction with signs of anaphylaxis:

  • Immediately call 911 or your local medical emergency number.
  • Ask if the person is carrying an epinephrine autoinjector (EpiPen, Auvi-Q, others) to treat an allergic attack.
  • If the person needs to use an autoinjector, ask whether you should help inject the medication. This is usually done by pressing the autoinjector against the person's thigh.
  • Have the person lie face up and be still.
  • Loosen tight clothing and cover the person with a blanket. Don't give the person anything to drink.
  • If there's vomiting or bleeding from the mouth, turn the person to the side to prevent choking.
  • If there are no signs of breathing, coughing or movement, begin CPR. Do uninterrupted chest presses — about 100 every minute — until paramedics arrive.
  • Get emergency treatment even if symptoms start to improve. After anaphylaxis, it's possible for symptoms to start again (recur). Monitoring in a hospital for several hours is usually necessary.

If you're with someone having symptoms of anaphylaxis, don't wait to see whether symptoms get better. Seek emergency treatment right away. In severe cases, untreated anaphylaxis can lead to death within half an hour.

An antihistamine pill, such as diphenhydramine (Benadryl), isn't enough to treat anaphylaxis. These medications can help relieve allergy symptoms, but they work too slowly in a severe reaction.

Symptoms of anaphylaxis include:

  • Skin reactions, including hives, itching, and skin that becomes flushed or changes color
  • Swelling of the face, eyes, lips or throat
  • Narrowing of the airways, leading to wheezing and trouble breathing or swallowing
  • A weak and rapid pulse
  • Nausea, vomiting or diarrhea
  • Dizziness, fainting or unconsciousness

Some common anaphylaxis triggers include:

  • Medications
  • Latex
  • Foods such as peanuts, tree nuts, fish and shellfish
  • Insect stings from bees, yellow jackets, wasps, hornets and fire ants

If you've had any kind of severe allergic reaction in the past, ask your doctor if you should be prescribed an epinephrine autoinjector to carry with you.

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July 02, 2022

  1. Anaphylaxis. Merck Manual Professional Version. //www.merckmanuals.com/professional/immunology-allergic-disorders/allergic,-autoimmune,-and-other-hypersensitivity-disorders/anaphylaxis. Accessed June 7, 2022.
  2. AskMayoExpert. Anaphylaxis. Mayo Clinic; 2022.
  3. Anaphylaxis. American Academy of Allergy, Asthma and Immunology. //www.aaaai.org/conditions-treatments/allergies/anaphylaxis. Accessed June 7, 2022.
  4. McHugh K, et al. Anaphylaxis: Emergency department treatment. Emergency Medical Clinics of North America. 2022; doi:10.1016/j.emc.2021.08.004.
  5. Burks AW, et al. Anaphylaxis. In: Middleton's Allergy: Principles and Practice. 9th ed. Elsevier; 2020. //www.clinicalkey.com. Accessed June 7, 2022.

See also

  1. Abdominal pain
  2. Allergies
  3. Allergy medications: Know your options
  4. Allergy shots
  5. Allergy-proof your home
  6. Alpha-gal syndrome
  7. Anaphylaxis
  8. Aspirin allergy
  9. Avoid rebound nasal congestion
  10. Blood in urine (hematuria)
  11. Creatinine tests
  12. Diarrhea
  13. Dizziness
  14. Does honey offer sweet relief for allergies?
  15. Drug allergy
  16. Egg allergy
  17. Fatigue
  18. Food allergy
  19. Food allergy or intolerance?
  20. Hemodialysis
  21. Hemodialysis
  22. Kidney dialysis: When is it time to stop?
  23. Milk allergy
  24. Nasal Cleaning
  25. Nasal spray addiction: Is it real?
  26. Nausea and vomiting
  27. Peanut allergy
  28. Penicillin allergy
  29. Seizures
  30. Shellfish allergy
  31. Sulfa allergy
  32. Urinalysis
  33. Wheat allergy
  34. Wheezing

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How much Benadryl does it take to stop an allergic reaction?

For mild allergy symptoms in adults and children ages 12 years and older, 25 mg to 50 mg of Benadryl is recommended every 4 to 6 hours. The most you should take in a 24-hour period is 300 mg. For children ages 6 to 11 years, the recommended dose is 12.5 mg to 25 mg every 4 to 6 hours as needed.

Can Benadryl help a severe allergic reaction?

Seek emergency treatment right away. In severe cases, untreated anaphylaxis can lead to death within half an hour. An antihistamine pill, such as diphenhydramine (Benadryl), isn't enough to treat anaphylaxis. These medications can help relieve allergy symptoms, but they work too slowly in a severe reaction.

Can you take 3 Benadryl for an allergic reaction?

Although online challenges may encourage it, it is not safe to take more than the recommended dosage of Benadryl. Doing so can lead to overdose and severe symptoms, including abnormal heart rhythms, hallucinations, seizures, and even death in rare cases.

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