Hydroxyzine Dosage Calculator for Dogs by Weight
Dose ranges on this page are published veterinary references for education only. Your veterinarian's prescribed dose always wins. When in doubt, call your vet first.
Hydroxyzine (Atarax, Vistaril) is an antihistamine veterinarians prescribe for dogs with itchy skin conditions such as atopic dermatitis, hives, and allergic reactions. The commonly published canine dose is 1 mg per pound of body weight, given 2–3 times daily.
Because it is prescription-only and has meaningful contraindications (glaucoma, urinary obstruction, pregnancy), the calculator below is a reference to use with your veterinarian's prescription — not a substitute for one.
Dose calculator
Dosage chart by weight
| Dog weight | Dose range per dose |
|---|---|
| 5 lb | 5 mg |
| 10 lb | 10 mg |
| 15 lb | 15 mg |
| 20 lb | 20 mg |
| 30 lb | 30 mg |
| 40 lb | 40 mg |
| 50 lb | 50 mg |
| 60 lb | 60 mg |
| 80 lb | 80 mg |
| 100 lb | 100 mg |
Chart uses the same conservative range as the calculator (1 mg per lb of body weight). Always confirm with your veterinarian.
Common formulations
- Tablets — 10 mg tablets
Also available as 25 mg and 50 mg tablets
Use the calculator above to convert any of these sizes into an amount for your pet's weight.
How often to give it
Every 8–12 hours (2–3 times daily). 1 mg per lb of body weight.
Common veterinary uses
- Atopic dermatitis and itchy skin
- Hives and allergic skin reactions
- Insect bite / vaccine reactions (vet-directed)
- Mild sedation for anxiety (vet-directed)
Safety warnings
Possible side effects
- Sedation / drowsiness (common)
- Dry mouth
- Difficulty urinating
- Rarely: paradoxical excitability
- Rarely: tremors
- Hydroxyzine requires a veterinary prescription — do not use leftover human medication.
- Use caution in working dogs — sedation can impair performance.
Do not use (or ask your vet first)
- Dogs with glaucoma
- Dogs with urinary or intestinal obstruction
- Dogs with severe heart disease
- Pregnant or nursing dogs
- With barbiturates, tranquilizers, or other CNS depressants unless your vet directs
When to see a veterinarian
- Trouble urinating or complete inability to urinate
- Tremors, seizures, or collapse
- Extreme or worsening sedation
- Itching does not improve within the timeframe your vet described
- Signs of allergic reaction to the drug itself (facial swelling, hives, vomiting)
Frequently asked questions
How much hydroxyzine can I give my dog?
The commonly published dose is 1 mg per pound of body weight, 2–3 times daily — for example, a 30 lb dog would be about 30 mg per dose. It is prescription-only, so your vet sets the exact dose.
How fast does hydroxyzine work in dogs?
It is well absorbed orally and typically starts working within 20–45 minutes, though full benefit for chronic itching builds over several days.
Can I give my dog hydroxyzine for anxiety?
Veterinarians do sometimes use it for mild sedation, but anxiety treatment should be vet-directed — there are often better-targeted options, and dosing for anxiety differs.
Is hydroxyzine stronger than Benadryl for dogs?
They are different drugs with different profiles. Hydroxyzine is prescription-only and often chosen for persistent atopic itch. Your vet decides which fits your dog's condition.
What are the main risks of hydroxyzine in dogs?
Its anticholinergic effects — dry mouth, urinary difficulty, and problems in dogs with glaucoma or obstruction. That is why it should never be started without veterinary guidance.
Sources
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Dose ranges on this page are published veterinary references for education only. Your veterinarian's prescribed dose always wins. When in doubt, call your vet first.