Flea Treatment for Dogs UK: Bravecto vs NexGard vs Simparica vs Credelio, and What Each Really Costs per Month

Every dog owner knows the moment: a back leg going at full speed behind an ear, a sudden nibble at the base of the tail, and you parting the fur looking for that tell-tale black speck. Fleas are not just an itch. Ticks carry Lyme disease, and in 2016 a cluster of dogs in Essex caught babesiosis, a tick-borne disease that had never before been passed on inside the UK.

That is why flea treatment for dogs has become a fixed monthly cost for most UK households. And it is where the brand choice matters: compared by cost per month rather than box price, and bought online rather than at the practice counter, the same protection can cost half as much.

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Bravecto, NexGard, Simparica and Credelio: What They Have in Common

The four best-known flea chews all belong to the same drug family, the isoxazolines. Each brand uses a different active ingredient:

• Bravecto (MSD): fluralaner. One chew lasts 12 weeks.
• NexGard (Boehringer Ingelheim): afoxolaner. Lasts one month.
• Simparica (Zoetis): sarolaner. Lasts one month.
• Credelio (Elanco): lotilaner. Lasts one month.

All four are flavoured chews. Once eaten, the medicine travels in the bloodstream, and the flea or tick dies when it bites. That means baths, rain and swimming don't wash it off, a real advantage over spot-ons for dogs that love a muddy pond.

In the UK all four are POM-V medicines: they can only be supplied with a veterinary prescription. That matters for the price, as you'll see below.

The Cheapest Flea Treatment for Dogs per Month: the Table

We priced each product for a medium dog, in the 10 to 20 kg band, at Pet Drugs Online on 16 October 2026. To compare products that last different lengths of time on the same scale, we worked out the cost per 30 days. The brands' weight bands don't line up exactly, so each band is shown.

• Credelio 450 mg (11 to 22 kg): £29.99 for 6 chews = £5.00 per month, about £60 a year.
• Simparica 40 mg (10 to 20 kg): £16.00 for 3 chews = £5.33 per month, about £64 a year.
• Frontline Plus spot-on (10 to 20 kg, no prescription needed): £39.98 for 6 pipettes = £6.66 per month, about £80 a year.
• Bravecto 500 mg (10 to 20 kg): £20.71 for one 12-week chew = £7.40 per 30 days, about £90 a year.
• NexGard 68 mg (10 to 25 kg): £45.67 for 6 chews = £7.61 per month, about £91 a year.

What about small dogs? Pomeranians, Yorkies, Chihuahuas

For small dogs the sums shift. We repriced the same products in the 2 to 5 kg band, the weight of a Pomeranian, Yorkshire Terrier or Chihuahua, at Pet Drugs Online on the same day:

• Credelio 112 mg (2.5 to 5.5 kg): £25.49 for 6 chews = £4.25 per month, about £51 a year.
• Simparica 10 mg (2.5 to 5 kg): £13.49 for 3 chews = £4.50 per month, about £54 a year.
• Bravecto 112.5 mg (2 to 4.5 kg): £15.73 for one 12-week chew = £5.62 per 30 days, about £68 a year.
• Frontline Plus spot-on (2 to 10 kg, no prescription needed): £39.98 for 6 pipettes = £6.66 per month, about £80 a year.

Two things to watch. First, the weight bands differ by brand, so a 2.3 kg dog may need a smaller strength than the ones listed. Second, NexGard's smallest chew (for 2 to 4 kg dogs) wasn't listed by this retailer when we checked, so it isn't included. Weigh your dog before you buy, and let your vet pick the band.

Does the prescription fee cancel out the saving?

Usually not. Following the CMA's final decision in March 2026, the fee for a written prescription is capped at £21 for the first medicine. Even with that fee, a year of Credelio bought online (about £60 + £21) costs less than six months of Simparica at the typical vet price. A single prescription can often cover several months' supply, so ask your vet how much it can cover and how long it is valid. We explain your rights in your legal right to a written prescription.

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Spot-On or Chew: Which Should You Choose?

Frontline Plus works differently. It combines fipronil, which kills fleas and ticks, with (S)-methoprene, which stops flea eggs and larvae from developing. You apply it to the skin at the back of the neck, and it spreads through the oils in the coat.

• For the spot-on: no prescription needed, and a good option for dogs that refuse tablets.
• For the chew: it doesn't wash off, doesn't leave a greasy patch, and there's nothing on the coat for children to touch straight after treatment.

The river problem: why vets now talk about "responsible" flea treatment

In 2020, researchers at the University of Sussex analysed Environment Agency samples from 20 English rivers (Perkins et al., Science of the Total Environment, 2021). Fipronil was found in 98% of samples and imidacloprid in 66%, two insecticides used in many pet spot-ons. Average fipronil levels were five times above the chronic safety limit for aquatic life. The likely route: the chemicals wash off treated dogs during baths and swims, and down household drains.

Since then, the British Veterinary Association has encouraged vets and owners to treat based on each pet's real risk rather than automatically all year round. In practice, that means two things for you: don't bathe or let your dog swim straight after a spot-on, and ask your vet whether year-round treatment is really needed for your dog's lifestyle.

Is Flea Treatment Safe? What the Evidence Says

Isoxazolines were approved after efficacy and safety studies and are used in millions of dogs worldwide. But there is one warning every owner should know about.

In September 2018, the US Food and Drug Administration (FDA) warned that products in this class, including Bravecto, NexGard, Simparica and Credelio, can cause neurological reactions in some dogs and cats: muscle tremors, loss of coordination and seizures. The FDA kept the products on sale, saying they remain safe and effective for most animals, and required the warning to appear on the labels.

5 Legitimate Ways to Pay Less for Flea Treatment

1. Compare cost per month, not box price. Divide the price by the days of protection and multiply by 30. That's how a single £20.71 Bravecto chew and a £45.67 six-pack of NexGard end up within pennies of each other.

2. Ask for a written prescription for the chews. At the prices above, a prescription-only chew bought online can cost less per month than an off-the-shelf spot-on, even after the prescription fee.

3. Buy the larger pack for monthly products. Six-packs usually work out cheaper per dose. The exception is a growing puppy, which may move up a weight band before the pack is finished.

4. Weigh your dog before you buy. The dose depends on the weight band. The wrong band either wastes money or leaves your dog under-protected. Never split a tablet or a pipette between two dogs.

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5. Treat the house during an infestation. Most flea eggs and larvae live in carpets, sofas and bedding, not on the dog. Hoover often and wash the bedding hot, so the problem doesn't come back and cost you extra doses.

When to Call the Vet

• After a tick bite: fever, lethargy, loss of appetite, pale gums or dark urine can be signs of tick-borne disease.
• After a dose: tremors, wobbliness, seizures, or vomiting or diarrhoea that doesn't settle.
• On the skin: sores, hair loss or intense itching that continues even with flea treatment up to date, which can be an allergy. Our guide to Apoquel for itchy dogs explains the options.

Frequently Asked Questions

Is Bravecto or NexGard better?

Both are isoxazolines and kill fleas and ticks. The practical difference is duration: one Bravecto chew lasts 12 weeks, NexGard lasts one month. For a 10 to 20 kg dog bought online, Bravecto worked out at about £7.40 per 30 days and NexGard at about £7.61. Your vet should make the choice.

Do I need a prescription for Bravecto in the UK?

Yes. Bravecto, NexGard, Simparica and Credelio are POM-V medicines. Ask your vet for a written prescription and you can fill it at an online pharmacy. Frontline Plus can be bought without one.

What is the best flea treatment for a small dog?

All four chews come in small-dog strengths, and the choice belongs to your vet. On cost, Credelio and Simparica were the cheapest per month for dogs of 2 to 5 kg in October 2026, at about £4.25 to £4.50 bought online with a prescription.

Can I use dog flea treatment on my cat?

No. Some dog spot-ons contain permethrin, which is highly toxic to cats. Only use products licensed for cats.

The Bottom Line

Bravecto, NexGard, Simparica and Credelio come from the same drug family and all protect your dog against fleas and ticks. What differs is how long each dose lasts, which is why the box price misleads. Worked out per month and bought online, Credelio and Simparica were the cheapest options in our comparison, and every chew cost a fraction of the typical vet price.

Choose the right product with your vet, then ask for the written prescription and compare the price. Over a dog's lifetime of monthly doses, that habit is worth hundreds of pounds.

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