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PetDosageChart

Antihistamine (H1 Receptor Antagonist) · For Cats

How much Atarax (Hydroxyzine) can I give my cat?

Standard Atarax dose for cats is 1.5 mg per kg (0.68 mg per lb), given Every 8-12 hours. Use the calculator below for your cat's exact weight, or jump to the weight-by-weight chart.

Onset
30-60 minutes
Duration
8-12 hours
Class
Antihistamine (H1 Receptor Antagonist)

Calculator estimate from Plumb’s Veterinary Drug Handbook. Not yet vet-reviewed — see our methodology .

This dosage information is for educational purposes only. Always consult your veterinarian before giving any medication to your pet. Dosages may vary based on your pet's health conditions, other medications, and individual factors.

Content reviewed by licensed veterinarians. Sourced from Plumb's Veterinary Drug Handbook and the Merck Veterinary Manual.

Dosage Calculator · 01

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Atarax dose by cat weight

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Dosage Chart · 02

Atarax dosage for cats by weight

Scroll sideways to see full table

Weight Low Dose Standard Max Safe Frequency
3 lbs (1.4 kg) 1.5mg 2mg 3mg Every 8-12 hours
4 lbs (1.8 kg) 2mg 2.5mg 3.5mg Every 8-12 hours
5 lbs (2.3 kg) 2.5mg 3.5mg 4.5mg Every 8-12 hours
6 lbs (2.7 kg) 2.5mg 4mg 5.5mg Every 8-12 hours
7 lbs (3.2 kg) 3mg 5mg 6.5mg Every 8-12 hours
8 lbs (3.6 kg) 3.5mg 5.5mg 7mg Every 8-12 hours
9 lbs (4.1 kg) 4mg 6mg 8mg (10mg tablet) Every 8-12 hours
10 lbs (4.5 kg) 4.5mg 7mg 9mg (10mg tablet) Every 8-12 hours
12 lbs (5.4 kg) 5.5mg 8mg (10mg tablet) 11mg (10mg tablet) Every 8-12 hours
14 lbs (6.3 kg) 6.5mg 9.5mg (10mg tablet) 12.5mg Every 8-12 hours
16 lbs (7.3 kg) 7.5mg (10mg tablet) 11mg (10mg tablet) 14.5mg Every 8-12 hours
18 lbs (8.2 kg) 8mg (10mg tablet) 12.5mg 16.5mg Every 8-12 hours
20 lbs (9.1 kg) 9mg (10mg tablet) 13.5mg 18mg (2 × 10mg) Every 8-12 hours
25 lbs (11.3 kg) 11.5mg (10mg tablet) 17mg 22.5mg Every 8-12 hours

Common Uses · 03

What is Atarax (Hydroxyzine) used for in cats?

Allergic dermatitis and itching Atopic dermatitis Urticaria (hives) Mild anxiety Mast cell tumor management (adjunctive)

Administration · 04

How to give Atarax to your cat

Hydroxyzine tablets or capsules can be given whole, hidden in a pill pocket or small piece of cheese or deli meat. For cats that refuse pills, the tablet can be crushed and mixed into a small amount of strong-flavored wet food, though this may reduce palatability. A compounded flavored liquid is often the easiest option for finicky cats. Use a pill gun to place the pill at the back of the tongue if giving directly, then offer a treat or syringe a small amount of water to ensure it is swallowed. Give with food to minimize stomach upset.

Available Forms

Tablet, Capsule, Oral suspension, Compounded liquid

Give with Food?

Yes — give with food

Side Effects · 05

Side effects of Atarax in cats

Common side effects

Sedation and drowsiness
Dry mouth
Decreased appetite
Paradoxical excitement or hyperactivity in some cats

Serious side effects — call your vet

  • Severe paradoxical agitation
  • Urinary retention
  • Cardiac arrhythmias (rare, at high doses)
  • Seizures (very rare)

Emergency · 06

When to call the vet

Call your vet immediately if your cat shows any of these signs:

  • Severe hyperactivity or agitation (paradoxical reaction)
  • Difficulty urinating or no urine output
  • Rapid or irregular heartbeat
  • Excessive sedation or inability to wake
  • Facial swelling or difficulty breathing (allergic reaction to the medication)

For Dogs

Looking for Atarax dosage for dogs?

View the Atarax dosage chart and calculator for dogs.

Related · 08

Related medications for cats

Sources · 09

Sources & references

The dosage information on this page is compiled from the following veterinary and pharmaceutical references:

  • Plumb's Veterinary Drug Handbook — the standard veterinary pharmacology reference used by veterinarians worldwide.
  • Merck Veterinary Manual — a trusted, peer-reviewed resource for veterinary professionals and pet owners.
  • DailyMed (FDA Drug Labels) — official FDA-approved drug labeling and prescribing information for Hydroxyzine.

Read more about our methodology and how we calculate dosages.

Transparency · 11

How this page was made

Sourced from Plumb's Veterinary Drug Handbook, the reference used in US vet schools. Every dose, frequency, and tablet count on this page is generated from that data, then checked against the published references below.

Sources cited
  • Plumb's Veterinary Drug Handbook
  • Merck Veterinary Manual
Calculator formula
Doses scale linearly from a standard basis of 1.5 mg per kg (0.68 mg per lb) of body weight, given Every 8-12 hours. The calculator multiplies that basis by your cat's weight and rounds to the closest available tablet size.
Last-reviewed status
Automated from Plumb’s, not yet vet-reviewed.

More on our methodology and editorial process — how we source, calculate, and review cats dosage data.

Frequently Asked · 07

Questions about this medication

Can hydroxyzine make my cat hyper instead of sleepy?
Yes, some cats experience a paradoxical reaction to hydroxyzine where they become more agitated and hyperactive instead of sedated. This is more common in cats than in dogs. If your cat becomes unusually restless, vocal, or aggressive after taking hydroxyzine, discontinue the medication and contact your vet. An alternative antihistamine may be better suited for your cat.
Is hydroxyzine better than Benadryl for cats?
Hydroxyzine is often considered more effective than diphenhydramine (Benadryl) for allergic conditions in cats because it has both antihistamine and mild anti-anxiety properties. It also has some mast cell-stabilizing activity. However, response varies between individual cats—some do better on one antihistamine versus another. Your vet can help determine which is the best choice for your cat.
How long does it take for hydroxyzine to help my cat's itching?
Hydroxyzine typically starts working within 30-60 minutes of oral administration. However, for chronic allergic conditions, it may take several days of consistent dosing to see the full benefit. Antihistamines work best as preventatives, so giving them before expected allergen exposure is ideal. If you see no improvement after 2 weeks of regular dosing, consult your vet about alternatives.
Can I give my cat hydroxyzine every day?
Yes, hydroxyzine can be given daily for chronic allergy management in cats. It is generally safe for long-term use when dosed appropriately. Your vet may recommend giving it every 8-12 hours depending on symptom severity. Periodic check-ups are advisable during long-term use to monitor for any side effects.
What is the correct hydroxyzine dose for a cat?
The typical hydroxyzine dose for cats is 1-2 mg/kg given every 8-12 hours. For an average 4 kg cat, this is approximately 5-10 mg per dose. Always start at the lower end to assess your cat's response, as some cats are more sensitive than others. Your veterinarian will determine the ideal dose based on your cat's specific condition and weight.

Safety · 10

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