How do I get rid of fleas in the house?

Fleas are a life-cycle problem, and that is why they feel impossible to clear. Adults on the pet are a small fraction; eggs fall off wherever the animal goes, hatch into larvae that live in carpet pile, and pupate into a stage that is resistant to insecticide and can wait weeks for vibration and warmth before emerging. Any treatment that ignores that timeline appears to fail.

Safety

What you'll need

• A vet-recommended flea treatment for each animal
• A vacuum cleaner
• A household flea spray with an insect growth regulator
• Sealed bags for bedding
• A flea comb and a bowl of soapy water (optional)

Step by step

1. Confirm it is fleas.Bites usually in clusters around ankles and lower legs, and flea dirt in the animal's coat — black specks that turn rusty red on damp white paper, because it is digested blood. That test is definitive.
2. Treat every animal in the house on the same day.All cats and dogs, not just the one that is scratching. Use a product your vet recommends — supermarket products vary a great deal in effectiveness, and resistance to some older actives is widespread.
3. Never use a dog product on a cat.Permethrin, common in dog spot-ons, is severely toxic to cats and causes seizures and death. If it happens, treat it as an emergency and ring a vet immediately.
4. Understand the numbers.Roughly speaking, adults on the pet are a small minority of the population; the rest are eggs, larvae and pupae in carpet, upholstery, bedding and floor cracks. That is why treating only the animal never works.
5. Wash all pet bedding at 60 degrees.And anything the animal sleeps on — a throw, a sofa cover, a duvet. Anything that will not wash hot goes in a sealed bag and is either frozen or discarded.
6. Vacuum thoroughly, then vacuum again tomorrow.Carpets, rugs, upholstery, along skirtings, under furniture, and the car if the animal travels. Vacuuming removes eggs and larvae and, importantly, the vibration triggers pupae to hatch so treatment can reach them.
7. Empty the vacuum outside every time.Into a sealed bag straight into the outside bin. A bagless cylinder left full is a breeding chamber.
8. Treat the house with a product containing a growth regulator.An insect growth regulator prevents eggs and larvae developing, which is what breaks the cycle. Spray carpets, upholstery and skirting edges to the label, move furniture and do underneath, and ventilate afterwards.
9. Expect and plan for a second wave.Pupae are protected and hatch over the following weeks, so new adults after a fortnight are normal rather than a treatment failure. Keep vacuuming daily for at least three weeks.
10. Keep the pet treated monthly through the season.Flea prevention is continuous. A single treatment during an infestation, then nothing, is how the same house has the same problem every autumn.
11. Look for a wildlife source if it recurs.Hedgehogs, foxes or rodents under a shed or in a loft, or a cat flap letting in a neighbourhood cat. A returning infestation with a treated pet usually has an outside source.

Tips

• Fleas in a house that has been empty are common — pupae wait for vibration. Vacuuming everything on day one is what wakes them up so treatment reaches them.
• Central heating means fleas are now a year-round UK problem rather than a summer one.
• A flea comb and a bowl of soapy water gives you an immediate read on whether the pet treatment is working.

Common mistakes

• Treating the pet and nothing else — Most of the population is not on the animal. New adults keep emerging from the carpet and it looks as though the treatment failed.
• Stopping when the bites stop — Pupae hatch over several weeks. Stopping vacuuming at the two-week mark is the commonest reason a cleared house is infested again a month later.

If it doesn't work

Questions people ask