Intestinal worms are extremely common in cats, particularly kittens and any cat that goes outdoors or hunts.
Most infections produce no visible signs at all, which is why treatment is scheduled by risk rather than triggered by symptoms.
This covers the main types, how cats catch them and what treatment intervals look like. The specific product and dose belong with your vet.
The main types
| Worm | How cats catch it | Visible sign | Risk to people |
|---|---|---|---|
| Roundworm | Mother’s milk, environment, prey | Spaghetti-like worms in vomit or faeces | Yes — especially children |
| Tapeworm | Swallowing infected fleas, or prey | Rice-grain segments near the tail | Low but possible |
| Hookworm | Environment, skin penetration, prey | Usually none; anaemia in heavy burdens | Yes — skin |
| Whipworm | Environment | Uncommon in cats | Low |
| Lungworm | Slugs, snails, prey | Coughing, breathing difficulty | No |
Roundworm and tapeworm account for the large majority of cases. The Companion Animal Parasite Council publishes detailed guidance on roundworm specifically.
Roundworm and kittens
Kittens are the highest-risk group, because roundworm larvae pass through the mother’s milk. A large proportion of kittens are infected from the first days of life.
Heavy burdens in kittens cause a distinctive picture: a pot-bellied appearance with poor overall condition, a dull coat, and failure to gain weight despite eating.
- Pot-bellied appearance with thin limbs.
- Poor growth and weight gain.
- Dull, staring coat.
- Diarrhoea, sometimes with visible worms.
- Vomiting, occasionally containing worms.
- Lethargy and poor appetite in heavy infections.
This is why kittens are wormed repeatedly from an early age rather than once. Our guide to what to do when you find newborn kittens covers early care.
Tapeworm and the flea connection
The commonest tapeworm in cats is transmitted by swallowing an infected flea during grooming — which means tapeworm and fleas travel together.
If you see rice-grain segments around the cat’s rear or in its bedding, treat for both. Worming alone leaves the source in place and reinfection follows.
Our guide to fleas and ticks in cats covers treating the household as well as the animal, which is the part people skip.
Why most infections are invisible
Adult cats with moderate worm burdens frequently show nothing. They eat normally, look well and pass no visible worms.
Visible signs generally indicate either a heavy burden or a vulnerable animal — a kitten, a senior, or a cat with another illness.
That is why the sensible approach is scheduled treatment based on lifestyle rather than waiting for symptoms.
How often to treat
Intervals depend on risk rather than on a universal rule, and your vet will tailor them.
| Cat | Typical interval | Reasoning |
|---|---|---|
| Kittens | Repeatedly from 2–3 weeks old | Transmission via milk is near-universal |
| Indoor-only adult, no fleas | Less frequently | Low exposure |
| Outdoor cat that hunts | Every 1–3 months | Prey is a constant source |
| Cat with fleas | Treat worms and fleas together | Tapeworm follows fleas |
| Household with young children | More frequently | Zoonotic risk |
| Newly adopted or found cat | On arrival, then per vet advice | History unknown |
| Community cats at TNR | At surgery | Often the only handling opportunity |
Indoor cats are not exempt. Fleas arrive on clothing, and an indoor cat that catches a single flea can acquire tapeworm.
The risk to people
This deserves a straight, proportionate answer. Roundworm and hookworm are zoonotic.
Roundworm eggs are ingested from contaminated soil or surfaces, most often by young children. In rare cases larvae migrate through tissue and can affect the eye or other organs.
Hookworm larvae can penetrate human skin, causing an itchy tracking rash, typically from contact with contaminated soil.
- Wash hands after handling cats, litter or soil.
- Scoop litter boxes daily — roundworm eggs need days to become infective.
- Supervise young children around litter boxes and sandpits.
- Cover outdoor sandpits when not in use.
- Wear gloves when gardening.
- Keep cats wormed on an appropriate schedule.
Daily scooping is the single most effective household measure, because freshly passed eggs are not yet infective.
Choosing a product
Different worms need different active ingredients, and no single product covers everything.
- A product effective against roundworm may not treat tapeworm.
- Some combination products cover worms, fleas and mites together.
- Dosing is by weight — guessing risks under-dosing or toxicity.
- Never use a dog product on a cat without veterinary confirmation.
- Kittens need formulations licensed for their age and weight.
That fourth point matters. Our guide to fleas and ticks in cats covers the permethrin warning, which applies to combination products too.
When to see a vet rather than self-treat
Routine worming is straightforward. These situations are not.
Visible worms in a kitten, diarrhoea lasting more than a day or two, weight loss, a pot-bellied kitten, blood in the faeces, or coughing and breathing difficulty all warrant an appointment.
Lungworm in particular presents as a respiratory problem rather than a digestive one, and is easily mistaken for asthma.
Our guides to why a cat is vomiting and how often a cat should see the vet cover where parasite control fits into wider care.
Worming a newly adopted or found cat
An unknown history means an unknown parasite status, and this is one of the first things to sort out.
- Ask the shelter or rescue what was given, and on what date.
- Take that record to your own vet within two weeks.
- Expect your vet to treat again if history is incomplete.
- Treat every animal in the household, not just the newcomer.
- Keep the new cat in its settling-in room until treated.
Retreating a cat that may already have been wormed is safe and standard practice where records are unclear. It is not a wasted expense.
Our guide to fleas and ticks in cats covers the parallel treatment, and the two frequently need doing together because tapeworm follows fleas.
Frequently Asked Questions
How do I know if my cat has worms?
Often you cannot — most adult cats with moderate burdens show nothing. Visible signs such as worms in faeces, a pot-bellied kitten or poor coat usually indicate a heavy burden or a vulnerable animal.
How often should I worm my cat?
It depends on lifestyle. Kittens need repeated treatment from a few weeks old, outdoor hunting cats typically every one to three months, and indoor cats less often. Your vet will tailor the interval.
Do indoor cats need worming?
Yes, though less frequently. Fleas arrive on clothing and shoes, and a single swallowed flea can transmit tapeworm. Indoor living reduces exposure but does not eliminate it.
What are the rice-like grains near my cat’s tail?
Tapeworm segments. The commonest cat tapeworm is transmitted by swallowing infected fleas, so treat for both — worming alone leaves the source in place and reinfection follows.
Can people catch worms from cats?
Roundworm and hookworm are zoonotic. Roundworm eggs are ingested from contaminated soil or surfaces, most often by children. Wash hands, scoop litter daily and cover outdoor sandpits.
Why does scooping the litter box daily matter?
Roundworm eggs need several days in the environment to become infective. Removing faeces daily means eggs are gone before they can transmit, making it the single most effective household measure.