Flea treatment for cats in infested rental home

Moving into a property with a known flea history is a tough situation — the fleas already living in the carpets and floorboards are often the bigger problem than anything on your cat right now. Before we get into what to use, it's worth knowing that cat flea treatment has one critical safety rule that doesn't apply to dogs: permethrin and certain other insecticides found in dog flea products are genuinely toxic to cats and can be fatal, so using the right product matters a lot. To point you in the right direction — how old and how heavy is your cat, are you seeing fleas on them already or trying to get ahead of it, and have you treated the home at all yet?

Thanks — that's really helpful. At 4.5kg she's a solid adult cat, so dosing won't be an issue. The fact you're already seeing live fleas on her three days in tells you the environmental burden in that flat is significant. Flea pupae can lie dormant in carpets for months and hatch in response to warmth and vibration, so you're likely dealing with a wave that's just getting started. Treating her is the immediate priority, but if you only treat the cat and not the home, you'll be fighting a losing battle — roughly 95% of a flea population lives off the animal.

For your cat, I'd go with Advantage 80 for cats (the 4–8kg tube). It's imidacloprid-based, kills adult fleas on contact within 24 hours, is safe for cats, and is available without a prescription. It doesn't require the flea to bite to work, which is a genuine advantage over some other spot-ons. Apply it to the back of the neck where she can't groom it off, and keep her away from other cats for a few hours after application. For the home — and this part is non-negotiable given what you've described — use Indorex Defence Household Flea Spray. It contains permethrin and pyriproxyfen: the permethrin kills adult fleas and the pyriproxyfen is an insect growth regulator that stops eggs and larvae developing. One can treats up to 40 square metres. The critical rule: your cat must be out of the treated rooms and the space must be fully ventilated before she comes back in — permethrin in the air is dangerous to cats even though it's fine once dry. Spray every carpet, skirting board, sofa, and under furniture, then keep her out for at least two hours with windows open.

Almost certainly not. The Indorex has a residual effect that lasts up to 12 months on carpets, so you shouldn't need to respray the whole flat — but you will likely see fleas hatching again over the next 2–6 weeks as dormant pupae wake up. That's normal and doesn't mean the treatment failed. Keep her on Advantage monthly for at least three months; if you still see live fleas on her after 48 hours of the first application, it could mean the environmental load is very heavy or re-exposure is happening fast, and it might be worth a vet visit to consider a prescription option like Bravecto or Stronghold. Vacuum aggressively every couple of days — it stimulates hatching, which brings the pupae into contact with the treated carpet faster and speeds up the clearance cycle.

Good plan — getting both on the same day is exactly right, because treating one without the other just prolongs it. One last thing: check any soft furnishings or cat bedding you brought with you from your previous home too, just in case anything hitched a ride. Good luck — with both elements covered properly, most people see the problem under control within four to six weeks.