Fleas on cats: how to check, treat and clear your home

Fleas on cats are common, even in indoor cats, and they’re more than an itch. They can cause skin disease, spread tapeworms and, in kittens, cause life-threatening blood loss. The good news is that they can be cleared with the right cat-safe products and a plan for your home. Not sure if that spot on the skin is fleas or something else? Try our symptom photo check.

How do I know if my cat has fleas?

Adult fleas are fast and small, so you often won’t see them. The easiest test is to look for flea dirt, which is flea poop made of digested blood.

1. Comb your cat over white paper. Use a fine-toothed flea comb, working from the neck down the back to the base of the tail.
2. Look for dark specks. Merck Veterinary Manual describes flea dirt as reddish black, pellet- or comma-shaped bits.
3. Do the wet test. Put the specks on damp cotton wool or a wet paper towel. International Cat Care explains that flea dirt slowly dissolves and leaves red-brown marks. Ordinary dirt stays dark.

Other signs of fleas on cats include:

• Scratching, licking or chewing at the skin, sometimes a lot
• Small crusty bumps, like millet seeds, under the fur along the back and neck
• Thinning hair or bald patches, especially along the back
• Tiny, fast-moving brown insects when you part the fur

Itching can have other causes, like mites or allergies. A vet needs to examine your cat to know the cause for sure.

What is the flea life cycle?

Understanding the life cycle explains why one treatment rarely solves the problem. International Cat Care estimates that 95% of fleas are in the home, not on your cat. Adult fleas on the cat lay eggs that fall into carpets, bedding and furniture.

Figures from Merck Veterinary Manual and CAPC.

CAPC notes that a female flea starts laying eggs within 20 to 24 hours of her first blood meal and can lay 40 to 50 eggs a day. Merck says the whole cycle usually takes 3 to 8 weeks, but can be as short as 12 to 14 days.

Cocoons are the hard part. International Cat Care notes they’re very resistant to treatment, and the flea inside can stay dormant for a long time before it hatches. That’s why new fleas can appear weeks after you start treating.

What is the safest flea treatment for cats?

The safest option is a vet-recommended cat flea product, used exactly as the label says and matched to your cat’s weight. International Cat Care warns that some off-the-shelf products from shops may not be safe for cats and may work less well than products from your vet.

Keep these rules in mind:

• Use a product made for cats. Check the label every time, even if you’ve used the brand before.
• Treat every pet. International Cat Care and CAPC both stress that every dog and cat in the home must be treated at the same time, or fleas keep moving between them.
• Keep going. CAPC recommends year-round flea control for cats throughout their lives, not just in summer.
• Ask about kittens and pregnant cats. Young kittens may be too young for some flea products, and pregnant or nursing cats need a product that’s safe for them.
• Don’t double up. Don’t combine flea products, or add sprays, powders or essential oils, unless your vet says it’s safe. Some essential oils are toxic to cats (see our guide to essential oils and cats).

If you’re unsure which product fits your cat, a quick vet call or chat can help before you buy.

Can dog flea treatment kill cats?

Yes. Some dog flea products contain permethrin, an insecticide that is very dangerous for cats. International Cat Care explains that a cat’s liver can’t break permethrin down into a harmless form, so it builds up in the body and attacks the nervous system.

The strength matters. The AAFP notes that permethrin dog products typically contain 45% to 60% permethrin, while products marketed for cats contain less than 0.1%.

Cats are poisoned in two main ways:

• An owner puts a dog spot-on on a cat, often by mistake or to save money
• A cat rubs against or grooms a recently treated dog, or lies where the dog has been

International Cat Care advises keeping cats and dogs apart for 72 hours after a dog is treated with a permethrin product. Permethrin can also be found in some flea powders, collars and insect-repelling clothing.

Signs of permethrin poisoning include drooling, twitching, trembling, sensitivity to touch or sound, a wobbly walk and seizures. If you think your cat has been exposed, call your vet or a poison hotline right away, even before signs appear. International Cat Care says cats treated early can make a full recovery, but severe cases with uncontrolled seizures may be fatal.

For other dangerous products around the home, see our guide to household toxins for cats.

How do I get rid of fleas in my home?

Treating the house is just as important as treating your cat.

• Vacuum often. Focus on carpets, rugs, sofas, under furniture and anywhere your cat sleeps. Empty the vacuum or throw the bag away outside straight after.
• Wash or replace bedding. Wash your cat’s bedding often, and throw out heavily infested bedding.
• Use a household flea spray. International Cat Care notes that a single application can last six months to a year, depending on the product. Ask your vet for one that’s safe to use in a home with cats, and keep pets out of the room until it’s dry, as the label directs.
• Repeat. Merck notes a second house treatment may be needed 7 to 10 days later, because new fleas keep emerging from cocoons.

Be patient. Merck says controlling an infestation can take 2 to 3 months. Seeing a few fleas after treatment starts is normal while cocoons in the home hatch.

What is flea allergy dermatitis?

Flea allergy dermatitis is an allergic skin reaction to flea bites. Cats with it can be very itchy.

Merck describes small bumps spread over the back, neck and face, along with hair loss. Some cats develop a “racing stripe” of inflamed skin along the back. The itching can range from mild to severe, and cats may lick and chew themselves raw.

Your vet may treat the itch and any skin infection, but strict flea control for every pet in the home is the main treatment. A vet needs to examine your cat to confirm the cause, because other allergies and mites can look similar.

Can fleas give my cat tapeworms?

Yes. The flea tapeworm, Dipylidium caninum, is spread by fleas. CAPC explains that cats become infected when they swallow an infected flea while grooming.

You may see small segments in the litter box or around your cat’s rear end. CAPC describes them as 10 to 12 mm long and shaped like cucumber seeds. Many infected cats show few other signs, though Merck notes some may have diarrhea.

Your vet can prescribe a dewormer. CAPC stresses that tapeworm treatment must be combined with flea control, or your cat is likely to be reinfected. Children can occasionally catch this tapeworm by swallowing an infected flea, though CAPC says the illness is generally mild and easily treated.

Fleas can also carry other infections, including Bartonella henselae, the bacteria behind cat scratch disease in people.

Why are fleas dangerous for kittens?

Fleas feed on blood, and a heavy infestation can cause serious blood loss in a small kitten. International Cat Care warns that flea infestations in kittens can cause life-threatening anemia, and CAPC lists death in young animals among the harms fleas cause.

Kittens may also be too young for some flea products, so don’t treat a kitten yourself. Call your vet for advice on a safe product and a plan for the mother cat and the home. If a kitten with fleas seems weak or won’t eat, see a vet the same day.

To budget for treatment and checkups, see our guide to cat vet visit costs.

Written by the CatsMed Team from the sources above. This guide isn’t reviewed by a veterinarian and isn’t a substitute for one. See how we research.