Flea Killer Sprays

Most flea sprays can be used on soft furnishings and pet resting areas, but check the label on the individual product first. Allow treated items to dry fully before pets or people use them again, and test an inconspicuous patch on anything that might mark.

It depends on the product. Many flea sprays contain an IGR (insect growth regulator) alongside an insecticide, which disrupts development so eggs and larvae do not reach adulthood. Sprays without one act only on the fleas present at the time. Read our guide to knockdown, residual and IGR treatments to work out which you are buying.

Follow the label on the individual product. Keep pets and children out of the room while you spray and until treated surfaces are completely dry, ventilate as directed, and do not spray food, food preparation surfaces, or anything a pet may lick or chew. Cover fish tanks and switch the pump off during application. If you have a cat, check the label before using any product intended for dogs - some ingredients, permethrin among them, are dangerous to cats. Store the can out of reach.

Follow the reapplication interval on the label. In general, re-treat after anything that disturbs the deposit - vacuuming, washing, a deep clean - and again if fresh activity appears. Flea control usually needs repeat treatments across two to four weeks, so consistency matters more than the strength of any single application.

Floors and the soft surfaces fleas actually live in: carpet, rugs, upholstery, room edges, under furniture, and wherever pets rest. Vacuum thoroughly first so the spray reaches the carpet base rather than sitting on debris, then empty the vacuum straight into an outside bin. Do not overlook cars, sheds and any room the pet uses that people rarely enter.

It probably did. Flea pupae are sealed in a cocoon that sprays do not penetrate, and they hatch in response to warmth and vibration - including the vacuuming and movement that follow a treatment. A second wave one or two weeks later is the normal pattern. Repeat as the label allows, keep vacuuming daily to bring the remaining pupae out, and expect each wave to be smaller than the last.

If there is no reduction after two full treatments, something is reintroducing them. The usual causes are an untreated pet, a pet that picks them up again outdoors, or an untreated space the animal uses - a car, a shed, a spare room. Treat every pet in the house with a veterinary flea product at the same time as the rooms, and hot-wash bedding at 60C or above. If it persists after a full treatment cycle, if the problem is building-wide in a block of flats, or if anyone is reacting badly to bites, it is worth calling a professional.