Is Sudafed (pseudoephedrine) toxic to cats?
No — emergency. Sudafed, Benylin Day & Night, and similar decongestants contain pseudoephedrine — a stimulant that's dangerous to cats at very small doses. A single tablet can cause significant toxicity in a 4 kg cat.
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Content compiled with reference to guidance from the Blue Cross, PDSA, Royal Veterinary College (RVC), Battersea, and Animal PoisonLine. This site does not provide veterinary advice — always consult a vet. Last reviewed: 27 September 2026.
Key facts
- Verdict: No — dangerous to cats. Sudafed (pseudoephedrine) should never be given deliberately.
- Category: Human OTC
- Onset: Signs can start 30–90 minutes — see the full timeline below.
- If it's already happened: Call your vet now, or the Animal PoisonLine on 01202 509000 (24/7, charges apply) — see the emergency steps below.
If your cat has just eaten sudafed (pseudoephedrine)
- Move your cat away from the Sudafed or decongestant.
- Don't induce vomiting at home — this is dangerous in cats.
- Call your vet or out-of-hours emergency vet immediately.
- If you can't reach a vet, call the Animal PoisonLine on 01202 509000 — 24/7, charges apply.
- Note how much Sudafed or decongestant was eaten, when, and your cat's weight.
What's the full picture?
Pseudoephedrine is a potent stimulant in cats — causes rapid heart rate, extremely high blood pressure, tremors, and seizures. The toxic dose is around 5 mg/kg; a single 60 mg Sudafed tablet is 15 mg/kg for a 4 kg cat.
Current UK OTC decongestants often use pseudoephedrine or phenylephrine. Phenylephrine is slightly less dangerous but still toxic. Combined products (cold and flu mixtures) often include paracetamol too, adding a second major toxin.
Cats that chew tablets they find on bedside tables, or lick up spilled syrup, are the common exposure. Store all cold medicines out of reach.
Symptoms to watch for
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Cat owner essentials
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Questions owners ask
How much Sudafed is dangerous to a cat?
A single standard 60mg tablet works out to around 15mg/kg for a 4kg cat — well above the roughly 5mg/kg toxic dose — so even one tablet is a serious overdose, not a borderline case. There's no fragment small enough to consider safe.
How soon would symptoms appear after a Sudafed exposure?
Agitation, a racing heart rate, dilated pupils, and tremors typically begin within 30–90 minutes. Seizures, severe high blood pressure, and dangerously elevated body temperature can follow within 1–12 hours. Given how quickly this progresses, call your vet or an emergency line the moment you suspect a tablet has gone missing, rather than waiting to see if symptoms appear.
Are there safe cold remedies for cats showing cold-like symptoms?
No human cold or flu product should ever be given to a cat. Sneezing, nasal discharge, or watery eyes in a cat usually point to a feline upper respiratory infection, which needs veterinary diagnosis and cat-specific treatment rather than a human decongestant, antihistamine, or combination remedy.
A lockable medicine box is the simplest way to keep human tablets out of reach of a curious cat.
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Related
Sources referenced for this guidance
- Veterinary Poisons Information Service (VPIS) — UK clinical toxicology reference used by vets
- International Cat Care — feline-specific clinical guidance
- BSAVA — British Small Animal Veterinary Association reference materials
- Merck Veterinary Manual — professional veterinary reference
About this guidance
Every entry on this site is compiled from published UK veterinary toxicology sources — International Cat Care, Veterinary Poisons Information Service (VPIS) references, RCVS-registered practice materials, and peer-reviewed feline medicine literature. Where the evidence is mixed, we err on the cautious side because cats are unusually sensitive to many common substances that are harmless to humans and even to dogs.
This is general information written for UK cat owners. It is not personalised veterinary advice for your specific cat, their age, weight, medical history, or the exact exposure you're dealing with. If your cat has eaten something or is unwell, call your vet first. The Animal PoisonLine on 01202 509000 is available 24/7 for a small fee and can tell you whether an emergency visit is needed.
Entries are reviewed and updated as new research emerges. Spotted an error? Let us know — corrections are investigated and applied within 24 hours. For more context on how we work, see about and our full disclaimer.
Last reviewed: · By the What Can My Cat Eat? editorial team