How often should you deworm and flea-treat cats and dogs?

Worms: the right frequency depends on risk

How often to deworm depends on how likely your pet is to pick up worms — there’s no single number for every cat or dog. The European Scientific Counsel Companion Animal Parasites (ESCCAP), in the June 2025 edition of its worm-control guideline, recommends deworming or testing stool at least 4 times a year whenever a pet’s risk can’t be clearly assessed. It also notes that studies show 1–3 dewormings a year don’t give enough protection. ESCCAP’s risk-based schemes look roughly like this:

Situation	ESCCAP suggestion (deworm or test stool)
Lives indoors, unlikely to eat prey, not fed raw food	1–2 times a year
Risk unclear	At least 4 times a year
Goes outdoors, meets other animals, hunts or eats raw meat or offal	4–12 times a year
Lives with children under 5–6, or older or immunocompromised people	Possibly monthly, depending on risk assessment
Puppies	From day 14, every 2 weeks until 2 weeks after weaning
Kittens	From 3 weeks, every 2 weeks until weaning

In North America, the Companion Animal Parasite Council (CAPC) takes a slightly different angle: year-round broad-spectrum control covering heartworm, intestinal parasites, fleas and ticks, plus stool tests at least twice a year for healthy adults and at least four times in a pet’s first year.

Either way, ESCCAP stresses that deworming should always follow a veterinary professional’s advice. Which group your pet is in, which product to use and how often are questions to settle with your vet — then follow your vet’s instructions.

Fleas and ticks: all year, at the product’s interval

Flea and tick prevention is generally recommended year-round, at whatever interval the product is designed for. CAPC’s flea guideline says dogs and cats should be treated year-round, throughout their lives, with flea control products. Intervals vary a lot between products — many are monthly, some last longer — so check the one your vet recommends.

Once fleas are established, CAPC says every pet in the home must be treated, and getting an infestation under control can take several months. Fleas also spread a tapeworm (ESCCAP lists fleas as the carrier of Dipylidium), so if you find fleas, ask your vet whether worm treatment is needed too.

Heartworm is its own schedule

Heartworm is spread by mosquitoes and is prevented and tested for differently from intestinal worms. Some products cover heartworm along with other parasites; others don’t. Write down what each product covers so you don’t double up or leave a gap — more in how often heartworm prevention is given.

How to set up a schedule

Let your vet assess your pet’s risk, pick the products, then put each one on a fixed day at its interval.

1. Tell your vet how your pet lives: indoors or out, hunting or raw feeding, young children or older people at home, other pets. These are exactly the factors ESCCAP uses to sort pets into risk groups.
2. Ask what each product covers, how often it’s given, and whether worming and flea control come in one product or two.
3. Ask whether regular stool testing makes sense. ESCCAP says testing at the same frequency as the suggested treatments, then treating what’s found, can stand in for routine deworming.
4. Log every dose: date, product, whether the whole tablet went down or the spot-on went on properly, and your pet’s weight that day.

Common mistakes

• Deworming once a year and calling it done. Unless your vet has assessed your pet as low risk, ESCCAP considers 1–3 treatments a year insufficient.
• Assuming indoor cats never need it. ESCCAP still suggests 1–2 treatments or stool tests a year for indoor cats.
• Using a dog flea product on a cat. International Cat Care warns that permethrin, an insecticide often found in spot-on dog flea treatments, is highly toxic to cats and one of the most common causes of cat poisoning worldwide — often because a dog product was put on a cat by mistake. Cats can also be poisoned by contact with a recently treated dog. Never swap products between species.
• Treating only the pet with fleas. CAPC says every pet in the home needs treatment to get fleas under control.
• Bathing too close to a spot-on. How soon before or after a bath you can apply a topical product depends on the label, so check it or ask your vet. For bathing itself, see how often to bathe a dog.
• One log for several pets. You end up not knowing which animal was last treated when.

How to remember

Worming and flea control often run on different intervals, so track them separately — and give each pet its own entries. Monthly products are easiest on a fixed date, such as the 1st of every month. The ones spaced a few months apart are the ones people forget; a reminder beats memory.

Keep an eye out in between, too: when you scoop the litter box or pick up after your dog, note anything unusual and mention it to your vet. At the yearly check-up and vaccines, ask your vet to review the parasite plan as well.