Benadryl Dosage for Dogs
The usual diphenhydramine dose range for your dog’s weight, converted into tablets and liquid. Use it to check the dose your vet gives you.
Dosing basics
Diphenhydramine is not approved by the FDA for dogs, but vets use it off-label. The Merck Veterinary Manual and Plumb’s list 2–4 mg per kg by mouth every 8–12 hours; many vets use the simpler 1 mg per pound.
- Adult tablets and capsules are usually 25 mg.
- Children’s liquid is usually 12.5 mg per 5 mL and may contain alcohol; never use a product with xylitol.
- Skip combination products (“-D”, decongestant, pain reliever).
Rounding to the nearest quarter tablet is fine; err on the lower side for small dogs.
Benadryl dosage chart for dogs
Starting dose at 1 mg per pound, with the 2–4 mg/kg published range.
| Dog weight | Starting dose | 25 mg tablets | Range (mg) |
|---|---|---|---|
| 5 lb (2.3 kg) | 5 mg | 0.25 | 5–9 |
| 10 lb (4.5 kg) | 10 mg | 0.50 | 9–18 |
| 15 lb (6.8 kg) | 15 mg | 0.50 | 14–27 |
| 20 lb (9.1 kg) | 20 mg | 0.75 | 18–36 |
| 25 lb (11.3 kg) | 25 mg | 1.00 | 23–45 |
| 30 lb (13.6 kg) | 30 mg | 1.25 | 27–54 |
| 40 lb (18.1 kg) | 40 mg | 1.50 | 36–73 |
| 50 lb (22.7 kg) | 50 mg | 2.00 | 45–91 |
| 60 lb (27.2 kg) | 60 mg | 2.50 | 54–109 |
| 70 lb (31.8 kg) | 70 mg | 2.75 | 64–127 |
| 80 lb (36.3 kg) | 80 mg | 3.25 | 73–145 |
| 100 lb (45.4 kg) | 100 mg | 4.00 | 91–181 |
Questions owners ask
How much Benadryl can I give my dog?
The commonly cited veterinary dose of diphenhydramine is 2–4 mg per kg (about 1–2 mg per pound), given every 8–12 hours (Merck Veterinary Manual; Plumb’s Veterinary Drug Handbook). Many vets start at 1 mg per pound. Always confirm with your own vet first.
Can I give my dog Benadryl for itching or allergies?
Vets sometimes suggest it for mild allergic reactions, insect stings or itchy skin, but antihistamines work poorly for chronic allergic itch in many dogs. If itching lasts, your vet has more effective options.
Which Benadryl products are safe for dogs?
Only plain diphenhydramine. Avoid anything labelled “D”, “Allergy Plus Congestion”, or with phenylephrine or pseudoephedrine, which can be dangerous. Check liquids for xylitol and alcohol; children’s liquid often contains alcohol.
What are the side effects of Benadryl in dogs?
Sleepiness is the most common. Some dogs get a dry mouth, urinary retention, fast breathing or, rarely, become excited instead of calm. Overdose signs include agitation, a racing heart and seizures — call a vet or poison line right away.
Can Benadryl help a dog with anxiety or car sickness?
Its sedating effect is unpredictable and it is not an effective anti-anxiety treatment. For travel or noise anxiety, ask your vet about medications designed for it.
When should I not give Benadryl?
Don’t use it without a vet’s advice if your dog has glaucoma, heart disease, high blood pressure, an enlarged prostate, is pregnant or nursing, or takes other medications. If your dog has facial swelling or trouble breathing, go to a vet instead.
Sources: Merck Veterinary Manual, “Antihistamines”; Plumb’s Veterinary Drug Handbook, diphenhydramine monograph; ASPCA Animal Poison Control Center.