This is a specific conversation about Flea treatment for cats — safe and effective options — ask about yours and get one honest answer for your exact situation.
inparticular.ai
Adopting a second cat is exciting — but you're right to think ahead about fleas. Even a well-cared-for rescue can bring fleas in, and once they're in your home, they spread fast. Before I suggest anything, there's one thing worth flagging upfront: cat flea treatment has a critical safety rule that doesn't apply to dogs. Permethrin and some other insecticides found in dog flea products are toxic to cats — even brief contact can be fatal — so it's essential to use only products licensed specifically for cats. Now, to point you to the right thing: how old and how heavy is your current cat, and do you know yet whether the cat you're adopting will have been treated before coming to you?
My Korat is 2 years old and about 4kg. The rescue says the new cat will have a vet check before we collect her, but I don't know if they'll treat for fleas. I'd rather just protect my cat proactively.
inparticular.ai
That's a sensible approach. A vet check doesn't always mean a flea treatment, so assuming nothing and protecting your Korat now is the right call. At 4kg and 2 years old, she's well within the adult range for standard spot-on treatments. One follow-up: is she on any other medication at the moment, or does she have any known sensitivities? And has she had any flea treatment before, or is this the first time?
No medications, no known sensitivities. She's never had fleas and I've never treated her — she's been fully indoor so it hasn't felt necessary until now.
inparticular.ai
Completely understandable — indoor cats often don't need it until something changes, and a new arrival is exactly that kind of change. My recommendation for your Korat is Advantage spot-on for cats (the 4kg+ formulation). It's imidacloprid-based, which means it's in a completely different chemical family from permethrin — entirely safe for cats. It kills fleas on contact within 24 hours, works for a full month, and doesn't require fleas to bite to be effective, which matters for prevention. It's available on Amazon UK in single or four-pack tubes. I'd start her on it a week or so before the new cat arrives, so she has full coverage from day one. You don't need a prescription — it's available over the counter.
Should I treat the new cat with the same thing when she arrives?
inparticular.ai
Yes, ideally — but check with the rescue first. If the vet has already applied a spot-on treatment at the vet check, you need to know what it was and when, so you don't double-dose within the same month. If she hasn't been treated, or if it's been more than four weeks, then Advantage is a good choice for her too, provided she's over 8 weeks old and above 1kg. The rescue should be able to tell you her weight. Once both cats are covered, you'll also want to treat your home — Indorex Defence household spray is worth having on hand, as flea eggs and larvae live in soft furnishings and carpets, not on the cat.
That's really helpful. I'll get a four-pack of Advantage and the home spray before she arrives. Thank you.
inparticular.ai
Perfect plan. Getting ahead of it now means you're not scrambling once the new cat is home. One last thing: keep the two cats separated for the first few days anyway while they adjust to each other — that also gives you a window to check the new arrival for any visible signs of fleas before full mixing. Good luck with the adoption.
