Dog Benadryl Dosage Calculator
Enter your dog's weight to get the safe Benadryl (diphenhydramine) dose — in milligrams, tablets, or children's liquid. Includes a safety check before you dose.
Use your pet's current weight. Not sure? Round to the nearest pound.
Safety check — read before dosing
Enter a weight to see the dose.
Educational estimate only — not veterinary advice. Confirm the dose and suitability with your veterinarian before giving any medication.
How much Benadryl is safe for a dog?
Benadryl is the brand name for diphenhydramine, an antihistamine vets commonly recommend for mild allergic reactions, itching, bug bites, and motion sickness in dogs. The widely accepted dose is 1 mg of diphenhydramine per pound of body weight, up to three times a day. Because tablets come in fixed strengths (usually 25 mg), the calculator above converts that into the actual number of tablets — or millilitres of children's liquid — for your dog's weight.
The single most important rule: use plain diphenhydramine only. Combination products labelled "Allergy Plus Congestion", "Sinus", or "-D" contain decongestants and pain relievers that can seriously harm dogs. Always read the active-ingredient panel, and run through the safety check in the calculator before giving anything.
How this Benadryl dose is calculated
The standard veterinary dose of diphenhydramine for a dog is about 1.0 mg per pound (2.2 mg/kg) of body weight, given every 8–12 hours, up to 3× per day. We multiply your pet's weight by that rate, then divide by the strength of the product you selected to show the number of tablets or millilitres — rounded to an amount you can actually measure.
Benadryl dosage chart for dogs by weight
A quick reference for common weights. Your pet's exact dose is shown by the calculator above.
| Dog weight | Dose (diphenhydramine) | Tablet |
|---|---|---|
| 5 lb | 5 mg | 0.25 tablets |
| 10 lb | 10 mg | 0.5 tablets |
| 15 lb | 15 mg | 0.5 tablets |
| 20 lb | 20 mg | 0.75 tablets |
| 25 lb | 24.9 mg | 1 tablet |
| 30 lb | 29.9 mg | 1.25 tablets |
| 40 lb | 39.9 mg | 1.5 tablets |
| 50 lb | 49.9 mg | 2 tablets |
| 60 lb | 59.9 mg | 2.5 tablets |
| 80 lb | 79.8 mg | 3.25 tablets |
| 100 lb | 99.8 mg | 4 tablets |
Doses shown for Tablet — 25 mg. Round to the nearest practical amount and confirm with your vet.
When not to give Benadryl
- Pets with glaucoma, cardiovascular disease, or hyperthyroidism without vet approval.
- Any product containing xylitol, decongestants (pseudoephedrine), or pain relievers (acetaminophen, ibuprofen).
Frequently asked questions
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