Itching / Allergies

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.

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.
Medicine Name: Cetirizine (Zrytec) May Give Every 6mo to 2yr 2-5yr 6yr and older
Liquid 1mg/1ml 24 hours 2.5 mg/2.5ml 5mg/5ml 10mg/10ml
Children's Chewable 24 hours 1/2 chew 1 chew 2 chew
Adult Tab 24 hours 1/2 tab 1 tab

The standard dose of cetirizine 10 mg once daily is appropriate for adults and children ages ≥6 years.
The usual dose for children ages 2 to 5 years is 5 mg once daily. Smaller children ages 6 months to 2 years may be given 2.5 mg once daily. The maintenance dose for patients with significant renal and/or hepatic insufficiency should be reduced by one-half. Zyrtec dosing once daily

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