Flea treatment for older cats — vet-approved OTC picks

It sounds like your vet has already pointed you in a helpful direction — they're happy for you to go over-the-counter, which is reassuring. Before I point you at anything specific, I want to flag the most important safety rule with cat flea treatments: products containing permethrin, or other pyrethroids, are safe for dogs but can be fatal to cats. Never use a dog flea product on a cat, and keep treated dogs away from cats until the product is dry. Now — how old and heavy is your cat, is this an active infestation or are you looking to prevent one, and have you treated the home as well?

Good to know — 4.5kg is a solid weight for a Domestic Longhair and puts her comfortably in the standard adult dosing range for most spot-on treatments. A couple of quick follow-ups: is she otherwise healthy, and is she on any other medications at the moment? Also, does she go outdoors or is she strictly indoor?

Perfect, that all makes this straightforward. For an 8-year-old cat with an active infestation, I'd recommend Advantage Spot-On for Large Cats (over 4kg). It contains imidacloprid, which is cat-safe, kills adult fleas within 24 hours, and also tackles flea larvae. It's applied to the back of the neck, works for four weeks, and is one of the most consistently reliable OTC options available — it's what a lot of vets point people toward when they say 'try the chemist first.' Because she goes outdoors, monthly reapplication will be important. One thing to be aware of: Advantage treats the cat, but roughly 95% of a flea infestation lives in the environment — carpets, bedding, soft furnishings. You'll want a household flea spray alongside this, or the infestation will keep cycling back.

For the home, Indorex Defence Household Flea Spray is the one I'd point you to — it's widely regarded as the best OTC household spray available, contains permethrin and pyriproxyfen (one kills adults, the other stops larvae developing), and a single can treats up to 40 square metres. The key caveat: it contains permethrin, so keep your cat out of treated rooms until surfaces are completely dry — usually a couple of hours. Spray carpets, skirting boards, under furniture, and anywhere she sleeps or sits. Wash her bedding at 60°C at the same time. Do all of this together and you should break the cycle within a few weeks.

Exactly right. Apply the Advantage first, let it dry, then do the house with Indorex when your cat is safely out of the way. Re-treat your cat monthly, especially since she's an outdoor cat. If you're still seeing live fleas on her after six to eight weeks of consistent treatment, that's when it's worth going back to the vet — there are prescription options like Bravecto or Broadline that are stronger. But for most cats in your situation, Advantage plus Indorex does the job cleanly.