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PetDosageChart

Nonsteroidal Anti-Inflammatory Drug (NSAID) / Antiplatelet Agent · For Cats

How much Bayer Aspirin (Aspirin (Acetylsalicylic Acid)) can I give my cat?

Standard Bayer Aspirin dose for cats is 8 mg per kg (3.63 mg per lb), given Every 48-72 hours ONLY (NOT daily). Use the calculator below for your cat's exact weight, or jump to the weight-by-weight chart.

Onset
30-60 minutes
Duration
48-72 hours in cats (due to slow metabolism)
Class
Nonsteroidal Anti-Inflammatory Drug (NSAID) / Antiplatelet Agent

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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Bayer Aspirin dose by cat weight

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Dosage Chart · 02

Bayer Aspirin dosage for cats by weight

Scroll sideways to see full table

Weight Low Dose Standard Max Safe Frequency
3 lbs (1.4 kg) 8.5mg 11mg 14mg Every 48-72 hours ONLY (NOT daily)
4 lbs (1.8 kg) 11mg 14.5mg 18mg Every 48-72 hours ONLY (NOT daily)
5 lbs (2.3 kg) 14mg 18.5mg 23mg Every 48-72 hours ONLY (NOT daily)
6 lbs (2.7 kg) 16mg 21.5mg 27mg Every 48-72 hours ONLY (NOT daily)
7 lbs (3.2 kg) 19mg 25.5mg 32mg Every 48-72 hours ONLY (NOT daily)
8 lbs (3.6 kg) 21.5mg 29mg 36mg Every 48-72 hours ONLY (NOT daily)
9 lbs (4.1 kg) 24.5mg 33mg 41mg Every 48-72 hours ONLY (NOT daily)
10 lbs (4.5 kg) 27mg 36mg 45mg Every 48-72 hours ONLY (NOT daily)
12 lbs (5.4 kg) 32.5mg 43mg 54mg Every 48-72 hours ONLY (NOT daily)
14 lbs (6.3 kg) 38mg 50.5mg 63mg (81mg tablet) Every 48-72 hours ONLY (NOT daily)
16 lbs (7.3 kg) 44mg 58.5mg 73mg (81mg tablet) Every 48-72 hours ONLY (NOT daily)
18 lbs (8.2 kg) 49mg 65.5mg (81mg tablet) 82mg (81mg tablet) Every 48-72 hours ONLY (NOT daily)
20 lbs (9.1 kg) 54.5mg 73mg (81mg tablet) 91mg (81mg tablet) Every 48-72 hours ONLY (NOT daily)
25 lbs (11.3 kg) 68mg (81mg tablet) 90.5mg (81mg tablet) 113mg Every 48-72 hours ONLY (NOT daily)

Common Uses · 03

What is Bayer Aspirin (Aspirin (Acetylsalicylic Acid)) used for in cats?

Blood clot prevention (thromboembolism prophylaxis) Aortic thromboembolism (saddle thrombus) prevention in cats with heart disease Anti-inflammatory use (very limited, with extreme caution) Fever reduction (rare, other options preferred)

Administration · 04

How to give Bayer Aspirin to your cat

CRITICAL SAFETY WARNING: Cats metabolize aspirin extremely slowly. NEVER give more frequently than every 48-72 hours. Use baby aspirin (81 mg) tablets for easier dosing. The tablet can be given whole or halved, hidden in a pill pocket or a small amount of soft food. Always give with food to reduce stomach irritation. Use a pill gun to place at the back of the tongue if giving directly. Mark your calendar clearly when each dose is given to avoid accidental double-dosing. If you miss a dose, simply give the next one at the regular 48-72 hour interval—never give two doses close together.

Available Forms

Tablet, Baby aspirin (81 mg)

Give with Food?

Yes — give with food

Side Effects · 05

Side effects of Bayer Aspirin in cats

Common side effects

Decreased appetite
Vomiting
Gastric irritation
Diarrhea

Serious side effects — call your vet

  • Gastrointestinal ulceration and hemorrhage
  • Kidney failure
  • Liver damage (hepatotoxicity)
  • Bone marrow suppression
  • Salicylate toxicity (panting, vomiting, seizures, death)

Emergency · 06

When to call the vet

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

  • Vomiting, especially with blood or dark coffee-ground material
  • Rapid breathing, panting, or open-mouth breathing
  • Black, tarry, or bloody stools
  • Lethargy, weakness, or collapse
  • Loss of appetite lasting more than 24 hours after a dose

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 Aspirin (Acetylsalicylic Acid).

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 8 mg per kg (3.63 mg per lb) of body weight, given Every 48-72 hours ONLY (NOT daily). 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

Why can't cats take aspirin like dogs or humans?
Cats have a critical deficiency in the liver enzyme glucuronyl transferase, which is needed to metabolize aspirin (and many other drugs). This means aspirin stays in a cat's body for 48-72 hours compared to 7-8 hours in dogs and 3-4 hours in humans. If dosed at the same frequency as dogs or humans, aspirin rapidly accumulates to toxic levels in cats. This is why cats can ONLY receive aspirin every 48-72 hours, never daily.
What is the correct aspirin dose for cats?
The dose for cats is 6-10 mg/kg given every 48-72 hours (NOT every 6-8 hours as in dogs). For blood clot prevention, many vets prescribe a low-dose baby aspirin (81 mg) every 72 hours for an average cat. For anti-inflammatory purposes, 10 mg/kg every 48 hours may be used short-term. NEVER give daily aspirin to a cat. Even one extra dose can push a cat toward toxicity.
What are the signs of aspirin poisoning in cats?
Signs of aspirin toxicity in cats include rapid breathing or panting, vomiting (possibly with blood), loss of appetite, lethargy, wobbliness, fever, abdominal pain, dark or bloody stool, increased drinking and urination, and in severe cases, seizures and coma. Aspirin toxicity is a medical emergency—if you suspect your cat has received too much aspirin, seek immediate veterinary care. Treatment includes decontamination, IV fluids, and supportive care.
Is aspirin used to prevent blood clots in cats with heart disease?
Yes, low-dose aspirin (81 mg every 72 hours for an average cat) has traditionally been used to reduce the risk of arterial thromboembolism in cats with hypertrophic cardiomyopathy (HCM). However, clopidogrel (Plavix) has largely replaced aspirin for this purpose, as studies have shown it to be more effective. Some cardiologists use both drugs together. Always follow your veterinary cardiologist's recommendations.
Can I give my cat baby aspirin?
Baby aspirin (81 mg) is the most commonly used aspirin formulation for cats because the dose is more manageable. However, even baby aspirin should ONLY be given under direct veterinary supervision and typically no more frequently than every 48-72 hours. An 81 mg baby aspirin may be appropriate for a 4-5 kg cat at the anti-platelet dose, but this should be confirmed by your vet. Never give aspirin to your cat on your own.

Safety · 10

More resources