Stronghold Plus For Cats: Everything You Need to Know

Scratchy cat? Buckle up, because the world of cat flea medication is vast and varied and can feel very overwhelming. Let us help you break it down by starting with an explainer on one of the most popular medications from one of the bigger brands. Stronghold Plus is a treatment for fleas, ticks and worms for cats. It uses a combination of the active ingredients selamectin and sorolaner to treat and protect against mixed parasitic infections.

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How does Stronghold Plus work?

Stronghold Plus’ active ingredient selamectin causes disruption of normal neurotransmission in parasites, which leads to their paralysis and death. It effectively breaks the flea lifecycle by killing adult fleas and preventing eggs hatching. It also kills anything in the larval stages. The other active ingredient, sarolaner, inhibits parasite receptors and stops the uptake of certain neurotransmitters which leads to death.

Parasites targeted by Stronghold Plus for cats

Stronghold Plus targets multiple parasites, covering your cats for:

• Fleas: killing adults and larval stage and preventing eggs from hatching.

• Mites: ear mites and scabies mite that causes mange in cats.

• Lice.

• Nematodes worms: roundworm and hookworm.

• Heartworm: has activity against, although heartworm is not native in the UK.

Benefits of using Stronghold Plus for cats

Prevention and treatment of common parasites

Stronghold Plus is a treatment but also prevention of common external (and some internal) parasites of cats. It keeps your pet safe from the issues these critters go on to cause, such as skin irritation and dermatitis, especially in those cats that are allergic to flea bites which, unfortunately, includes quite a lot of cats. Not only does Stronghold Plus protect directly against infestations, it also protects indirectly as it also reduces the risk of transmission of tapeworm from fleas by killing fleas before transmission occurs. However, it’s important to know it doesn’t treat tapeworm itself.

Stronghold Plus does not have action against lungworm and so if your cat has a taste for slugs or snails, which are common intermediate hosts, talk to your vet about the best treatment plan for your pet.

Ease of application

Stronghold Plus is a spot-on topical treatment which is applied onto the skin at the back of the neck where your cat cannot reach to lick it off. It can be used on a monthly basis.

Convenience

Having a monthly treatment that treats both external and internal parasites is convenient, particularly in those cats who are a bit feisty when you try and give them medication, as it reduces the need for multiple treatments.

Safety

While there is potential for some adverse events with any medication, Stronghold Plus is well tolerated in cats when used as directed. Side effects are uncommon but pruritus or alopecia at the application site along with redness and drooling have been reported. Very rare adverse reactions (fewer than one animal per 10,000 treated) report ataxia, convulsions, vomiting or diarrhoea – all of which are mostly transient.

Stronghold Plus should not be used in cats that are ill, debilitated or underweight for their size and age, along with those who have had previous sensitivity to any of the ingredients.

How to use Stronghold Plus for cats

Holding the pipette firmly, puncture the applicator seal by depressing the cap, then part the fur at the base of your cat’s neck at a point that’s hard to reach for them to lick. Apply the liquid onto the skin exposed without massaging, squeeze the pipette 3–4 times to fully empty the contents, avoiding contact with your fingers. 

Stroking and petting near the site should be avoided after application, and children should not play with treated cats for four hours after treatment. It is recommended that you treat them in the evenings to reduce any human transfer of the product and cats should not be permitted to sleep in the same bed as owners after treatment (good luck with that one!).

How quickly does Stronghold Plus start working?

Stronghold Plus kills adult fleas and attached ticks within a day and prevents new infestations for up to five weeks. While it works quickly on existing parasites, breaking the full flea life-cycle and eliminating environmental flea eggs requires consistent monthly application and treating of all pets and the home.

Stronghold Plus compared to other products

Stronghold Plus covers for the same parasites as normal Stronghold (fleas, mites, lice, roundworms and hookworms) with the addition of covering against ticks and providing activity against heartworm. Stronghold Plus is a prescription-only medication that cannot be bought over the counter. Your vet will be able to prescribe it after a recent physical assessment to ensure it is suitable for your individual cat and to get an up-to-date weight reading as dosage is decided by weight. It is also available from other external stockists including online with a prescription from your vet.

Bottom line: Stronghold Plus for cats

Stronghold Plus is a broad-spectrum prescription-only parasiticide that protects cats from external parasites such as fleas, ticks, lice and mites along with internal parasites such as roundworm, hookworm and heartworm.

It is a topical spot-on treatment that is used once a month by placing the liquid into the skin at the back of the neck.

While well-tolerated, uncommon side effects include itchiness and alopecia at the site of application, redness or drooling. Due to its combination of active ingredients targeting mixed parasites it is a convenient method to treat multiple parasites at once.

Frequently asked questions: Stronghold Plus for cats

Is Stronghold Plus safe for kittens?

Stronghold Plus should only be used in cats aged over eight weeks old and weighing at least 1.25kg.

Can I use Stronghold Plus on pregnant or lactating cats?

Stronghold Plus has not been fully tested on use in pregnant or lactating cats, but the active ingredients have been tested separately or tested in other animals, and so use in pregnant or lactating animals should only be used according to benefit-risk assessment as judged by your vet.

What’s the difference between Stronghold and Stronghold Plus?

Stronghold Plus covers all the parasites normal Stronghold treats (fleas, lice, mites, roundworms and hookworms) plus the addition of ticks and heartworm.

Is Stronghold Plus safe for all cats?

Stronghold Plus can be used in all cats unless too young, underweight, ill or for those that have had prior sensitivities to any of the ingredients. As every animal is an individual, have a discussion with your vet to see if Stronghold Plus would be suitable for your cat before use.

References

Zoetis UK Limited. “Stronghold plus Spot-on Solution for Cats (GB).” Noahcompendium.co.uk, NOAH. Accessed 7 Jan. 2026.

“Stronghold plus | European Medicines Agency (EMA).” European Medicines Agency (EMA), 23 Mar. 2017. ‌

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