Stronghold®
Stronghold offers a range of prescription spot-on flea treatments for both cats and dogs that treat a number of external and internal parasites for 4 weeks. You can also buy Stronghold Plus for cats for added protection.

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How Does Stronghold Flea Treatment Work?
Stronghold flea treatments offer your pet four weeks' worth of parasite protection in just one treatment.
The active ingredient, Selamectin, kills fleas as well as their eggs and larvae to effectively break the flea life cycle. As well as killing fleas, Stronghold for dogs and cats also treats:
In Dogs:
- → Roundworms
- → Sarcoptic mange
- → Biting lice
- → Prevention of heartworm disease
In Cats:
- → Adult roundworms
- → Adult hookworms
- → Biting lice
- → Ear mite infestations
Stronghold also offers Stronghold Plus for cats, which offers even more protection for cats with, or at risk from, mixed parasitic infestations by ticks and fleas, lice, mites, gastrointestinal nematodes or heartworm.
You can buy Stronghold flea treatments online from us in the following dosages.
Stronghold for Cats
Stronghold Plus for Cats:
Stronghold Flea Treatment for Dogs:
- → Stronghold for Puppies and Kittens (15mg)
- → Stronghold for Toy Dogs (30mg / 2.6kg - 5kg)
- → Stronghold for Small Dogs (60mg / 5.1kg - 10kg)
- → Stronghold for Medium Dogs (120mg / 10.1kg - 20kg)
- → Stronghold for Large Dogs (240mg / 20.1kg - 40kg)
- → Stronghold for Extra-Large Dogs (360mg / 40.1kg - 60kg)
Always make sure you choose the correct dosage when buying prescription flea treatments online, and only use Stronghold products on the species and weight specified on the prescription.
How Long Does Stronghold Take to Work on Fleas?
Once applied, Stronghold flea treatments kill all fleas within 24 hours and continue to work and protect your pet from parasites for up to 4 weeks.
Is Stronghold for Fleas and Worms?
Yes! As well as treating flea infestations, Stronghold spot-on solution for cats and dogs also treats some internal parasites, including hookworms and roundworms.
Can You Buy Stronghold Without a Vet Prescription?
All Stronghold and Stronghold Plus products are prescription-only veterinary medicines, which means they can only be purchased using a valid, in-date prescription from your vet.
You can learn more about ordering a prescription medicine for your pet from Pet Drugs Online on our prescription information page. For your pet's safety, always be wary of any organisation offering to sell Stronghold or any other prescription-only veterinary medicines without a prescription.
Please note, while we have an onsite vet to oversee the sales of prescription medicines, we do not offer veterinary consultations or advice.