Fleas at home with a dog or cat: what to do

Treat the pets and their surroundings together.

The answer in 2 lines. Scratching pets and itchy ankles can point to fleas, but bites alone cannot identify the cause. Ask your vet about suitable treatment for every pet, and tackle bedding, carpets and favourite resting places alongside it. Keep following the treatment instructions even when you stop seeing fleas. Never use a dog-only flea product on a cat: concentrated permethrin can cause fatal poisoning. If you have already applied the wrong product, contact a vet immediately and keep the packaging.

Start here

Check your pet's coat with a flea comb. Look for moving fleas and dark specks, especially around the lower back. Skin damage or persistent scratching also needs veterinary advice.
Contact your vet with each pet's species, age, current weight and details of any treatment already used. Agree suitable treatment for all pets in the household.
Vacuum carpets, upholstered furniture, floor edges and places where pets sleep. Empty the vacuum carefully and dispose of the contents securely.
Wash pet bedding and washable covers at the hottest temperature their care labels allow. Include blankets used in the car.

Stop: danger

Wrong treatment on a cat: call a vet immediately, even before symptoms appear. Drooling, twitching, wobbling or seizures after exposure need urgent treatment. Take the packaging.
A person may have been poisoned: follow the NHS poisoning guidance. Call 999 or go to A&E for suspected exposure to something harmful; call 111 if you are unsure whether the substance is harmful. Do not make the person vomit.

Why fleas keep appearing

Treating the animal alone can leave an infestation developing around it. Eggs fall into bedding and furnishings, while immature fleas remain hidden in the environment. Newly emerging adults can therefore appear after treatment has begun.

This does not automatically mean the medicine has failed. Keep cleaning and follow the prescribed repeat schedule. Do not apply extra doses because you have spotted another flea. The RSPCA's flea guide explains the life cycle: use its treatment and prevention sections to understand why both pet and home need attention.

Choose treatment for the individual animal

Check the species, weight range, minimum age and application instructions on the actual pack. Tell the vet if your pet is pregnant, unwell or taking other medicine. Rabbits and other small pets need their own advice: a product suitable for a dog or cat is not automatically safe for them.

The PDSA flea advice explains treatment options and when an examination is needed. Use it to prepare questions for your vet, rather than choosing solely by packaging or price.

What not to do

Treating only the pet that scratches most: other animals can maintain the infestation.
Splitting a large dog's pipette between smaller animals or adding another product without advice.
Using a household insecticide directly on an animal.
Assuming a product described as natural is safe for cats.

Make the home treatment safe

Concentrate cleaning on the places your pets actually use, including underneath furniture and around their beds. Continue regularly rather than stopping as soon as the visible fleas disappear.

If a household flea product is needed, follow its label exactly. Remove people and animals as instructed, protect other pets such as fish, and observe the stated ventilation and re-entry requirements. These vary between products. If the problem persists, ask a qualified pest controller to assess it and explain how their treatment fits with your animals' medicines.

Extra care when dogs and cats live together

A cat can be poisoned by contact with a dog recently treated with concentrated permethrin, including through grooming or shared bedding. Tell your vet that you have both species before choosing treatment.

Read the Veterinary Medicines Directorate's permethrin warning, particularly the dog spot-on precautions. Follow the product's separation instructions. If accidental application occurs, seek immediate veterinary treatment; the guidance also advises washing the product off with water and mild detergent.

Good to know

Heavy infestations can make vulnerable animals seriously unwell. Seek veterinary advice for weakness, pale gums or extensive skin damage.
Fleas can be involved in tapeworm infection: ask whether your pet also needs appropriate worm treatment.
These animal-care principles also apply elsewhere in the UK; local pest-control services and availability vary.

Illustrative example: in Leeds, Alex finds fleas on the dog but the cat seems comfortable. The vet recommends a suitable product for each animal and explains how to prevent contact with wet treatment. Alex washes their bedding, vacuums their resting places and keeps to the agreed schedule instead of adding another dose when a flea reappears.

A made-up story, for illustration.

Bobby

Sources, verification, confidence

Verified on 5 November 2026, for England. Confidence: high for the permethrin warning and the need to treat pets and their environment together; medium for how quickly an individual infestation will clear. Treatment choice, cleaning duration and repeat applications depend on the animals, product and infestation.