Flea treatment comes in two main formats: topical spot-on liquids applied to the skin, and oral tablets or chewables. Both can be highly effective, but each has distinct advantages and drawbacks. Here is an honest comparison to help you choose.

Spot-On: The Pros

  • No need to persuade your pet to eat something: Particularly useful for fussy dogs and most cats, who are notoriously difficult to tablet
  • Some are available without prescription: Frontline, Advantage, and Seresto collars can be bought over the counter
  • Broader parasite coverage: Products like Advocate combine flea treatment with worming in a single application
  • Often cheaper: Non-prescription spot-ons like Frontline cost as little as £4–£6 per dose

Spot-On: The Cons

  • Wet, greasy fur: The application site remains damp for 24–48 hours and can leave oily residue
  • Must avoid bathing/swimming: Most spot-ons require you to avoid bathing your pet for 48 hours before and after application
  • Contact concerns: Young children should avoid touching the application site until dry. Some products are toxic to cats if applied to a dog in the same household and the cat grooms the dog
  • Resistance issues: Fipronil-based spot-ons (Frontline) have shown declining effectiveness in parts of the UK
  • Can be rubbed off: Pets that roll in grass or are groomed by housemates may not get the full dose

Tablet: The Pros

  • No wet fur or contact concerns: Once swallowed, the product is entirely internal
  • Cannot be washed or rubbed off: Bathing, swimming, and grooming have no effect on efficacy
  • Fast-acting: Products like Nexgard start killing fleas within 4–8 hours
  • No resistance issues (yet): Isoxazoline-class tablets remain highly effective against UK flea populations
  • Good for multi-pet households: No risk of one pet ingesting another's topical treatment

Tablet: The Cons

  • Prescription only: All effective oral flea tablets in the UK require a vet prescription, adding cost and inconvenience
  • Must be eaten: Some dogs spit tablets out or refuse flavoured chewables. Most cats will not willingly take oral flea treatment
  • Higher cost: Prescription tablets cost £8–£15 per monthly dose, compared to £4–£8 for many spot-ons
  • Seizure warning: Isoxazoline products carry a precaution for dogs with a history of seizures
  • Limited worm coverage: Most flea tablets do not cover worms (except Nexgard Spectra), so you need a separate wormer

Cost Comparison

Annual costs for a medium-sized dog:

  • Budget spot-on (Frontline): £48–£72/year
  • Premium spot-on (Advocate): £96–£180/year
  • Oral tablet (Nexgard): £96–£180/year
  • Extended tablet (Bravecto): £80–£140/year

What About Cats

For cats, spot-ons are almost always the better choice. Very few cats will willingly take oral flea medication, and the stress of forcing a tablet can damage the owner-pet relationship. Broadline or Stronghold Plus spot-ons are the most commonly recommended prescription options for cats.

The Verdict

For dogs: oral tablets are generally more effective and convenient, but cost more. For cats: stick with spot-ons. For budget-conscious owners: a Seresto collar (£25–£35 lasting 7–8 months) offers the best value if tick protection is your priority.

Last updated: March 2026. Prices based on UK veterinary and retail data.