Foods Poisonous to Cats (and the Safe Human Foods You Can Share)

Cats are fussy, but they're also curious, and the two don't always cancel each other out. A cat that would never touch a piece of onion might happily lick gravy off a plate, groom lily pollen out of its fur, or absorb a flea treatment meant for the dog. Some of these are mildly upsetting; a few are deadly within days. Here's what genuinely harms UK cats, how much it takes, and exactly what to do if it happens.

The quick toxic list

If you only remember a handful of things, remember these. They cover the exposures UK vets see most often.

| Food or item | Why it's dangerous | Rough danger level | | --- | --- | --- | | Lilies (true lilies & daylilies) | Acute kidney failure from tiny amounts, including pollen | Life-threatening | | Onion, garlic, leeks, chives | Destroy red blood cells (anaemia) | High | | Permethrin (dog flea spot-on) | Tremors, seizures, death | Life-threatening | | Chocolate | Theobromine affects heart and nervous system | Moderate to high | | Grapes, raisins, sultanas, currants | Linked to kidney damage | Uncertain but treat as high | | Xylitol (sugar-free sweetener) | Blood-sugar crash, possible liver damage | High (mainly dogs) | | Alcohol & raw bread dough | Ethanol poisoning, bloating | High | | Caffeine (tea, coffee, energy drinks) | Heart and nervous-system stimulant | Moderate to high |

The rest of this page explains each one, how much matters, and the safe foods you can share without worry.

Onion, garlic, leeks and chives

This whole family, the alliums, contains compounds called organosulphoxides that damage a cat's red blood cells and can cause a type of anaemia. Cats are more sensitive to it than dogs, and it doesn't matter whether the onion is raw, cooked, dried or powdered. In fact concentrated forms are worse: onion gravy granules, garlic powder, stock cubes, some baby foods and the odd "garlic supplement" sold as a natural flea remedy are all risks.

The damage can be cumulative, so small amounts eaten regularly are a problem, not just one big binge. Signs often lag a few days behind the meal and include lethargy, pale gums, reduced appetite, and reddish or brown urine. If your cat has been nibbling anything oniony or garlicky, don't wait for symptoms.

A common mistake: assuming "a little bit of gravy won't hurt." Rich human leftovers are one of the more frequent low-level allium exposures, precisely because owners don't think of gravy as onion.

Chocolate and caffeine

Chocolate contains theobromine and caffeine, both of which cats struggle to process. Cats are far less likely than dogs to actively seek out chocolate, but it still happens, especially with cake, ice cream or hot-chocolate dregs. The darker the chocolate, the more theobromine, so cooking chocolate and high-percentage dark are the most dangerous, while white chocolate has very little.

Caffeine on its own is just as much of a concern. Tea bags, coffee grounds, energy drinks and some human painkillers can all cause a racing heart, restlessness, tremors and, in bad cases, seizures. Keep used coffee pods and tea bags out of reach; cats have been known to chew them.

Grapes, raisins, sultanas and currants

Grapes and their dried forms are firmly linked to kidney failure in dogs, and vets treat them as a risk to cats too. The honest picture: the evidence in cats is thinner than in dogs, and researchers now think tartaric acid is the likely culprit. Because the toxic dose seems unpredictable and the consequence is so severe, the sensible approach is simple: keep all grapes, raisins, sultanas and currants away from your cat, and that includes things like mince pies, Christmas cake, hot cross buns and flapjacks.

Alcohol and raw bread dough

Alcohol is toxic to cats in small quantities, and it turns up in more than just drinks: some desserts, sauces and even household products contain it. A cat is tiny, so a splash goes a long way.

Raw bread dough is a sneaky one. In the warm environment of a cat's stomach, the yeast keeps fermenting, producing alcohol and gas. That can cause both alcohol poisoning and a painfully bloated stomach. Never leave proving dough where a cat can reach it.

Xylitol (and "birch sugar")

Xylitol is an artificial sweetener in sugar-free chewing gum, some sweets, certain peanut butters, and a few medicines and toothpastes. It's sometimes listed as "birch sugar" on labels. In dogs it causes a dangerous drop in blood sugar and can lead to liver failure, which is why the PDSA flags it as one of the most serious pet poisons.

The evidence for xylitol harming cats is much weaker, and cats seem less affected than dogs. But given how little is known and how severe the dog reaction is, treat sugar-free products as off-limits and phone for advice if your cat swallows any. This is exactly the kind of grey area where a quick call beats guessing.

The two non-food killers every cat owner must know

Lilies

Lilies aren't a food, but they cause more sudden feline deaths than almost anything on this list, so they belong here. True lilies (Lilium species, such as Easter, Tiger, Stargazer and Asiatic lilies) and daylilies (Hemerocallis) can cause fatal kidney failure in cats. Every part is toxic: petals, leaves, stem, pollen and even the water in the vase. A cat doesn't have to eat the plant; brushing past the flower and then grooming pollen off its coat is enough.

Cats Protection is blunt about this, and so am I: don't have these lilies in a home or garden with cats. If you're sent a bouquet, check it and pull any lilies out before the cat investigates. Early signs are drooling, vomiting, hiding and going off food, often within hours, followed by kidney damage over the next day or two. This is a same-hour emergency, not a wait-and-see.

Not every plant called a "lily" is the deadly kidney type. Peace lily, calla lily and lily of the valley are different plants with their own risks (mouth irritation or heart effects), but the true lilies and daylilies are the ones that cause the swift kidney failure. If you're unsure which you've got, treat it as dangerous.

Permethrin: the dog flea treatment that kills cats

This is the one that catches out loving, careful owners. Permethrin is an insecticide used in many dog spot-on flea treatments. Dogs handle it fine. Cats can't break it down the same way, so a dose that's safe for a dog can cause severe tremors, twitching, seizures and death in a cat.

It happens two ways: applying a dog product to a cat by mistake, or a cat grooming or snuggling a recently treated dog in the same household. The RSPCA lists permethrin among the common causes of cat poisoning for good reason. Only ever use flea products labelled for cats, check with your vet if you have both species, and keep a treated dog separate from the cat until the product has dried and settled.

Safe human foods you can share

Cats are obligate carnivores, so their diet should be built on proper cat food. Treats and scraps should stay under about 10% of what they eat. Within that, a few plain human foods are fine in small amounts:

| Usually safe (plain, small amounts) | Notes | | --- | --- | | Cooked chicken or turkey | No skin, bones, salt, oil or seasoning | | Cooked white fish or a little tinned tuna | Boneless; tuna as an occasional treat, not a staple | | Cooked egg | Fully cooked, never raw | | Small amount of cooked plain meat | No onion, garlic or gravy | | A few pieces of cooked pumpkin or carrot | Some cats like them; purely optional |

A word on milk. Cow's milk isn't poisonous, but most adult cats can't digest lactose, so it commonly causes an upset stomach and diarrhoea. The saucer-of-milk image is a myth worth retiring. Fresh water is what your cat actually needs.

Avoid raw meat and raw fish as a routine (risk of bacteria and, with some raw fish, an enzyme that depletes vitamin B1), cooked bones (splinter risk), and anything heavily salted or seasoned.

What to do if your cat eats something poisonous

Act quickly and calmly. The single biggest mistake is "watching and waiting" to see if the cat gets ill, because with lilies and alliums the damage is already underway before symptoms show.

1. Move your cat away from the source and stop any further eating or licking. 2. Don't try home remedies. Never make your cat vomit and never give salt water, milk or anything else unless a vet tells you to. Inducing vomiting can do more harm. 3. Gather the evidence. Note what it was, roughly how much, and when. Keep the packaging, plant or a sample if you safely can. 4. Phone for advice straight away. Ring your own vet, or your out-of-hours emergency vet if it's after hours. UK practices always have emergency cover. 5. Consider the Animal PoisonLine on 01202 509000. It's the UK's only 24-hour poison advice line for pet owners, run by the Veterinary Poisons Information Service. There's a fee per call, but they'll tell you whether you genuinely need to rush to the vet or can safely monitor at home. 6. If poison gets on the coat, wash it off with mild pet shampoo and warm water so the cat doesn't groom it in.

For prevention, a bit of routine helps: keep human food, bins and used tea bags secure, store flea treatments where they can't be muddled up, and think twice before bringing cut flowers home.

Common mistakes to avoid

• Feeding gravy, stuffing or Sunday-roast trimmings that contain onion or garlic.
• Assuming a plant labelled "lily" is safe, or that pollen alone can't harm.
• Using a dog flea treatment on a cat, or letting a cat cuddle a freshly treated dog.
• Leaving raw bread dough proving on a worktop.
• Giving milk as a treat because "cats love milk."
• Waiting for symptoms before ringing a vet. Speed is what saves kidneys and lives.

If your cat is otherwise poorly or off its food, it's worth understanding related feline behaviours too. Our guide to whisker fatigue in cats explains one surprisingly common reason cats go off eating from a bowl.

Sources

• RSPCA – Poisoning in cats
• PDSA – Poisons and hazards for your pets
• Cats Protection – Plants poisonous to cats
• Animal PoisonLine (Veterinary Poisons Information Service)