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This calculator provides general guidance only. DO NOT give Benadryl to children under 2 years without a doctor's approval. Always read product labels and consult a healthcare provider for proper dosing, especially for young children or those with health conditions.
Calculate the appropriate diphenhydramine dose for your child based on weight and age
| Weight (lbs) | Weight (kg) | Dose (mg) | Liquid (12.5mg/5mL) | Chewables |
|---|---|---|---|---|
| 22-32 | 10-14 | 12.5 | 5 mL (1 tsp) | 1 tablet |
| 33-43 | 15-19 | 18.75 | 7.5 mL (1½ tsp) | 1½ tablets |
| 44-54 | 20-24 | 25 | 10 mL (2 tsp) | 2 tablets |
| 55-65 | 25-29 | 25 | 10 mL (2 tsp) | 2 tablets |
| 66-76 | 30-34 | 25-37.5 | 10-15 mL | 2-3 tablets |
| 77-87 | 35-39 | 37.5 | 15 mL (3 tsp) | 3 tablets |
| 88+ | 40+ | 50 (max) | 20 mL (4 tsp) | 4 tablets |
* For children 6 years and older. Children 2-5 years should only use under doctor supervision.
Common:
Paradoxical (especially in children):
Call 911 or go to ER immediately if your child experiences:
For severe allergic reactions (anaphylaxis): Use epinephrine (EpiPen) first if available, then call 911. Benadryl is NOT a substitute for epinephrine in anaphylaxis.
Benadryl (diphenhydramine) is NOT recommended for children under 2 years old without explicit direction from a healthcare provider. The FDA has not established safe dosing for this age group, and serious side effects can occur. Always consult your pediatrician first.
Oral Benadryl typically starts working within 15-30 minutes, with peak effects occurring at 1-2 hours. Effects usually last 4-6 hours. For faster relief in emergencies, liquid forms may work slightly quicker than tablets.
Yes, Benadryl can generally be given with acetaminophen (Tylenol) or ibuprofen (Motrin) as they work differently. However, AVOID combination cold medicines that already contain diphenhydramine to prevent accidental overdose. Always check labels.
This is called a 'paradoxical reaction' and is more common in children than adults. Instead of sedation, some children experience hyperactivity, excitability, or insomnia. If this occurs, consult your doctor about alternative antihistamines.
Benadryl is intended for short-term use (a few days). If your child needs antihistamines regularly for allergies, talk to your doctor about non-sedating options like cetirizine (Zyrtec) or loratadine (Claritin) that are designed for daily use.
The active ingredient (diphenhydramine) is the same, but concentrations differ. Children's liquid is 12.5mg/5mL, while adult tablets are typically 25mg each. Never assume you can give half an adult dose—always use children's products and proper dosing.
While Benadryl can help dry up runny noses and post-nasal drip that cause some coughs, it's not specifically a cough suppressant. For coughs, consider products designed for that purpose. The American Academy of Pediatrics recommends against cough medicines for children under 6.