Itching / Allergies

Is Your Child Sick?®

Dosages for Diphenhydramine (Benadryl) for different weights

Medicine Name: Diphenhydramine (Benadryl) May Give Every 20-24 lbs. 25-37 lbs. 38-49 lbs. 50-99 lbs. 100+ lbs.
Liquid 12.5 mg/ 1 teaspoon (tsp) 6-8 hours 3/4 tsp. 1 tsp. 1-1/2 tsp. 2 tsp. -
Liquid 12.5 mg/ 5 milliliters (mL) 6-8 hours 4 mL 5 mL 7.5 mL 10 mL -
Chewable 12.5 mg 6-8 hours - 1 tab. 1-1/2 tab. 2 tab. 4 tab.
Tablets 25 mg 6-8 hours - 1/2 tab. 1/2 tab. 1 tab. 2 tab.
Capsules 25 mg 6-8 hours - - - 1 cap. 2 cap.

When to Use. Treatment of allergic reactions, nasal allergies, hives and itching.

A longer lasting alternative with less side effects, such as sedation or agitation, would be cetirizine (Zyrtec), loratadine (Claritin), and fexofenadine (Allegra). Follow the dosing directions on the package or discuss with your doctor.

Table Notes:

  • AGE LIMITS. For allergies, don't use under 1 year of age. (Reason: it causes most babies to be sleepy). For colds, not advised at any age. (Reason: no proven benefits). They should be not be given if under 4 years old. If under 6 years, don't give products with more than one ingredient in them. (Reason: FDA recommendations 10/2008).
  • DOSE. Find the child's weight in the top row of the dose table. Look below the correct weight for the dose based on the product you have.
  • MEASURE the DOSE. Syringes and droppers are more accurate than teaspoons. If possible, use the syringe or dropper that comes with the medicine. If not, you can get a med syringe at drug stores. If you use a teaspoon, it should be a measuring spoon. (Reason: regular spoons are not reliable.) Keep in mind 1 level teaspoon equals 5 mL and that ½ teaspoon equals 2.5 mL. 
  • ADULT DOSE. 50 mg
  • HOW OFTEN. Repeat every 6 hours as needed.
  • CHILDREN’S BENADRYL FASTMELTS. Each fastmelt tablet equals 12.5 mg. They are dosed the same as chewable tablets.

Customized from Itching Allergies v0.1 7/8/2025