Guide · Parasites
Flea treatment schedule for dogs and cats
Fleas are a year-round problem in a heated house, and the treatment gap that causes an infestation is almost always a forgotten date rather than a failed product. Here is the usual UK interval and what to do about the other 95% of the fleas — the ones in your carpet.
Last reviewed: 2 September 2026
In short
How often to treat
| Product type | Usual interval | Notes |
|---|---|---|
| Spot-on | Every 4 weeks | Apply to skin, not fur; keep dry for 48 hours |
| Oral tablet or chew | 4 weeks to 12 weeks | Interval varies by product — read the label |
| Collar | Up to 8 months | Check fit and condition regularly |
Dose is by weight. A growing puppy or kitten moves through weight bands quickly, so re-check the band at every treatment rather than buying a year's supply in one size.
Winter still counts
Fleas do not have an off season indoors. Heated homes keep eggs and pupae developing through December and January, and pupae can lie dormant for months before hatching when they detect warmth and vibration. Stopping treatment in autumn is the single most common reason a household gets a spring infestation.
Treating the house, not just the pet
Roughly one flea in twenty is on your pet at any moment. The rest are eggs, larvae and pupae in carpet pile, skirting gaps, sofa seams and pet bedding. Wash all bedding at 60°C, vacuum thoroughly including under furniture and empty the vacuum straight into an outside bin, and use a licensed household spray if your vet recommends one. Expect it to take several weeks to clear fully, because dormant pupae keep hatching.
Cat safety
Never use a dog flea product on a cat. Permethrin, present in some dog spot-ons, is highly toxic to cats and poisoning can be fatal. In a mixed household, separate the animals until a dog's spot-on has dried. If a cat is exposed, contact a vet immediately — this is an emergency.
Never miss the date
Monthly is easy to say and hard to keep. Note the product and date every time you treat, and set the next date immediately. Pawfile schedules the next flea treatment on a 28-day cycle alongside worming and boosters, and emails you a digest of anything due in the week ahead.
This is general information, not veterinary advice. Vaccination protocols vary by country, brand of vaccine and your pet's individual risk. Always follow the schedule your own vet recommends. Pawfile is an admin tool for keeping those records and reminders organised — it does not diagnose or treat.
Common questions
- How often should I flea treat my dog or cat?
- Most spot-on and tablet flea products last four weeks, so monthly treatment year round is the usual advice in the UK. A few prescription products last up to three months — always follow the interval on the packaging rather than a general rule.
- Do I need to treat for fleas in winter?
- Yes. Centrally heated homes let fleas complete their life cycle all year, so stopping over winter is the most common reason an infestation appears in spring.
- Why do I still see fleas after treating my pet?
- Only around five per cent of a flea population lives on the animal. The rest are eggs, larvae and pupae in carpets, bedding and soft furnishings. Treat the pet, wash bedding hot, vacuum thoroughly and use a household spray where advised.
- Can I use a dog flea product on my cat?
- No. Several dog products contain permethrin, which is highly toxic to cats and can be fatal. Use only a product licensed for the species and weight in front of you, and keep treated dogs away from cats until the spot-on is dry.
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