How to Apply Selamectin to Cats Correctly
By Dr. Zubair Khalid, DVM, MS, PhD ·
Applying selamectin to a cat means parting the fur at the base of the neck, placing the full dose directly on the skin, and keeping your cat from licking the spot until it dries. The medicine works through the skin, so it has to land on skin and not on the hair coat. Most cats tolerate the application well when it is done calmly and in the right spot.
This article is educational and is not a substitute for veterinary diagnosis or treatment.
Quick Answer
- Part the fur at the base of the skull, between the shoulder blades, until you can see skin.
- Squeeze the entire tube onto that one spot of skin, not along the hair.
- Keep the tube tip against the skin so the liquid does not run down the coat.
- Prevent your cat from licking the area until it is dry, which usually takes a short time.
- If you miss a monthly dose, apply it as soon as you remember, then restart your monthly schedule.
What Is Selamectin and What Do Veterinarians Use It For?
Selamectin is a topical antiparasitic medicine for cats. It is applied to the skin as a spot-on product and is absorbed through the skin to kill parasites. In the United States, selamectin is often prescribed alone or in a combination product that also contains sarolaner [1].
Veterinarians use selamectin to prevent and treat parasite problems. The selamectin and sarolaner combination is given monthly and provides a minimum dose of 6.0 mg/kg selamectin and 1.0 mg/kg sarolaner [1]. This combination kills fleas and works fast enough to reduce flea egg production, which lowers the risk of flea allergic dermatitis and infection with the tapeworm Dipylidium caninum [1].
The combination also has broad activity against ticks. It has shown efficacy above 90% for at least four weeks after a single treatment against 10 tick species, including Amblyomma americanum, Dermacentor variabilis, Ixodes scapularis, and Rhipicephalus sanguineus [1]. Because it kills ticks quickly, it can reduce the chance that a tick passes certain infections to your cat, including Borrelia burgdorferi, the bacterium that causes Lyme disease [2].
Selamectin is also used for certain skin mites. Topical selamectin, and more recently topical selamectin plus sarolaner, has been shown to treat notoedric mange, also called feline scabies, a contagious and intensely itchy skin condition caused by Notoedres cati mites [3].
Your veterinarian decides which product and which parasites it should cover based on your cat's lifestyle, region, and health.
How Selamectin Works
Selamectin moves through your cat's skin and into the bloodstream after you apply it. From there it reaches parasites that feed on your cat, such as fleas and ticks. Sarolaner, when it is part of the product, works in a different way, and the two ingredients act together to kill fleas with high efficacy and speed [1].
This is why placement matters. If the dose sits on the hair instead of the skin, less of it is absorbed. If your cat licks it off before it dries, the dose your cat actually receives may be lower than intended.
How to Apply Selamectin to Cats: Step by Step
This is the part most owners want to get right. Take your time and set up before you open the tube.
Before You Start
Read the label directions your veterinarian gave you. Confirm the tube is the correct product for cats, since some parasite products are made for dogs and are not safe for cats. Have the tube at room temperature if your veterinarian or the label says so. Choose a calm moment, ideally when your cat is relaxed after a meal or a nap.
Step 1: Position Your Cat
Hold your cat gently against your body or have a second person help. You want your cat's back facing you and the head slightly away. A towel wrapped around the front legs can keep a wiggly cat still without causing stress.
Step 2: Find the Spot at the Base of the Neck
The target area is the skin at the base of the skull, between the shoulder blades. This is the spot your cat cannot easily reach with its tongue. Part the fur with your fingers or with the tube itself until you see a strip of bare skin.
Step 3: Place the Tube Against the Skin
Keep the tip of the tube touching the skin the whole time. If you hold the tube above the coat, the liquid will run along the hair and be wasted.
Step 4: Squeeze Out the Full Dose
Empty the entire tube onto the skin in one spot. Do not split the dose between two locations unless your veterinarian tells you to. Do not massage it in. Let it soak in on its own.
Step 5: Keep Your Cat From Licking
Hold your cat or distract it for a few minutes so it does not twist around to groom the spot. Once the area is dry, licking is much less of a concern. If you have more than one cat, keep them separated until the product dries, because a housemate may groom the treated cat.
Step 6: Wash Your Hands
Wash your hands with soap and water after applying the product. Avoid touching the treated spot on your cat until it is dry.
If you want a broader review of technique for both dogs and cats, see How to Apply Flea and Tick Medication to Your Dog or Cat Correctly.
Dosing Basics for Selamectin
Who Decides the Dose
Your veterinarian sets the dose. It is based on your cat's body weight and health, and on which parasites the product needs to cover. The selamectin and sarolaner combination is dosed to provide a minimum of 6.0 mg/kg selamectin and 1.0 mg/kg sarolaner [1]. Never guess a dose or split a tube meant for a larger pet.
How Often It Is Given
The selamectin and sarolaner combination is given monthly [1]. Your veterinarian will tell you the schedule for your cat's specific product and situation.
What to Do If You Miss a Dose
If you forget a monthly dose, apply it as soon as you remember. Then continue on your regular monthly schedule from that new date. Do not apply two doses at once to catch up. If you are unsure how to reset the schedule, call your veterinary clinic.
What to Do If Your Cat Licks the Product
Some cats will groom the spot before it dries. A small amount of licking is common and usually causes mild drooling or brief stomach upset. Offer fresh water and watch your cat. If your cat vomits, seems very sleepy, trembles, or behaves oddly, call your veterinarian or a pet poison control line right away. Keep the product packaging so you can tell them exactly what was applied.
What to Do If the Dose Lands on the Hair
If most of the dose went onto the fur instead of the skin, the cat may not get the full benefit. Do not apply a second full dose on your own. Call your veterinarian for guidance.
Side Effects of Selamectin in Cats
Most cats have no problems after a selamectin application. In laboratory studies of the selamectin and sarolaner combination, no treatment-related adverse reactions occurred in any study [4]. Still, any medicine can cause reactions in some cats.
| Side effect | How common or serious | What to do |
|---|---|---|
| Mild drooling or lip smacking after licking the spot | Common and usually mild | Offer water, watch your cat, and call your vet if it continues |
| Brief vomiting or soft stool | Uncommon and usually mild | Withhold food for a short time if your vet advises it, and call if it repeats |
| Sleepiness or unsteady walking | Uncommon, can be more serious | Call your veterinarian the same day |
| Tremors, twitching, or seizures | Rare but serious | Treat as an emergency and call your vet or poison control now |
| Redness, itching, or hair loss at the application site | Uncommon | Do not reapply, and ask your vet about a different product |
| Signs of an allergic reaction such as facial swelling or trouble breathing | Rare but serious | Seek emergency veterinary care immediately |
If your cat has a history of seizures or a neurologic condition, tell your veterinarian before using any spot-on antiparasitic.
Who Should Not Take Selamectin and What Interacts With It
Selamectin is not right for every cat. Your veterinarian will review your cat's health before prescribing it.
Cats who are sick, underweight, or recovering from illness may need a different plan. Very young kittens and pregnant or nursing cats should only receive a product when the veterinarian confirms it is appropriate for that life stage.
Do not use a dog product on your cat. Some dog parasite products contain ingredients that are toxic to cats, and the dose is wrong for a cat's size.
Tell your veterinarian about every medicine your cat takes, including other flea or tick products, dewormers, steroids, and seizure medications. Using two parasite products with overlapping ingredients can raise the risk of side effects. If your cat is on other skin treatments, ask how to space them out. For cats with allergies or itchy skin, see How to Give Your Cat Allergy Medication Safely.
If your cat has flea allergy dermatitis, the itch and skin damage need their own plan along with parasite control. See How To Treat Flea Dermatitis In Cats.
Overdose and When to Call a Veterinarian or Poison Control
An overdose can happen if a cat licks off a fresh application, if two doses are given too close together, or if the wrong product is used. Signs to watch for include heavy drooling, vomiting, wobbliness, tremors, or seizures.
Call your veterinarian right away if you think your cat received too much. If your clinic is closed, call a pet poison control hotline. The ASPCA Animal Poison Control Center is available at (888) 426-4435, and the Pet Poison Helpline is available at (855) 764-7661. A consultation fee may apply.
Bring the product packaging with you or have it in hand when you call. The exact product name, the amount applied, and the time of application help the veterinarian decide what care your cat needs.
Limitations and When to Contact a Veterinarian
This article covers general steps. Your cat's individual case needs a veterinarian who knows your cat's weight, health history, and parasite risk.
Contact your veterinarian the same day if your cat vomits repeatedly, seems unusually sleepy, walks unsteadily, or has redness and swelling at the application site. Call right away if your cat has tremors, twitching, trouble breathing, or facial swelling. Those are emergencies.
Schedule a routine visit if the product does not seem to be controlling fleas or ticks, if you keep missing doses, or if you want to switch products. If your cat needs other at-home treatments, such as fluids for a chronic condition, see How to Give Your Cat Subcutaneous Fluid Injections at Home. For dose details on the combination product, see Revolution Plus for Cats: Selamectin Sarolaner Feline Dose Guide.
Frequently Asked Questions
Can I apply selamectin to a cat if the fur is wet?
Wait until your cat's coat is dry. Water on the skin and hair can dilute the product and change how well it is absorbed. If your cat gets wet soon after application, call your veterinarian to ask whether the dose still counts.
How long after applying selamectin can I pet my cat?
You can pet your cat, but avoid the treated spot until it dries. Wash your hands after touching the area. Keep young children away from the application site until it is dry.
What happens if my cat licks selamectin right after I apply it?
Mild drooling or brief stomach upset is the most likely result. Watch your cat for a few hours. Call your veterinarian if you see vomiting, sleepiness, tremors, or any behavior that worries you.
Can I use selamectin on a kitten?
Only if your veterinarian says the product is appropriate for your kitten's age and weight. Kittens are dosed by weight, and some products are not labeled for very young cats. Never use a dog product on a kitten.
Do I need to skip a month if my cat had a mild reaction?
Do not decide this on your own. Call your veterinarian before the next dose is due. They may switch products, change the timing, or check your cat first.
Can I bathe my cat after applying selamectin?
Ask your veterinarian about bathing timing for your specific product. Some products need time to spread and absorb before a bath. If your cat must be bathed for a medical reason, tell your veterinarian when the last dose was applied.
Related Articles
- How to Apply Flea and Tick Medication to Your Dog or Cat Correctly
- Revolution Plus for Cats: Selamectin Sarolaner Feline Dose Guide
- How to Give Your Cat Subcutaneous Fluid Injections at Home
- How to Give Your Cat Allergy Medication Safely
- How To Treat Flea Dermatitis In Cats
- How to Give Your Cat a Transdermal Medication: Tips for Success
- Selamectin for Cats Without a Vet Prescription: What to Know
- Selamectin for Dogs: Dosage, Side Effects, and How to Use It
- Selamectin for Dog Ear Mites: Does It Work and How to Use It
References
- A review of the parasiticidal efficacy of a selamectin plus sarolaner combination for use on cats. Veterinary parasitology, regional studies and reports, 2026.
- Efficacy of Revolution® Plus (selamectin plus sarolaner) for the prevention of transmission of Borrelia burgdorferi from infected Ixodes scapularis to cats. Parasites & vectors, 2026.
- Efficacy of a spot-on combination product containing selamectin and sarolaner (Stronghold® Plus) in the treatment of naturally occurring Notoedres cati infestations in cats. Frontiers in veterinary science, 2025.
- Efficacy of Revolution® Plus (selamectin plus sarolaner) against Amblyomma americanum (lone star ticks) in cats. Parasites & vectors, 2025.