Selamectin is a topical medication for cats used to treat and prevent common parasites like fleas, ear mites, heartworms, hookworms, and roundworms. It is applied directly to the skin and provides both internal and external parasite protection in one treatment.
Using the correct selamectin dosage for cats is very important. The dose depends on your cat’s weight, and giving the wrong amount can reduce effectiveness or increase the risk of side effects. In some cases, veterinarians may also use selamectin for other conditions (off-label), so it’s important to follow their instructions carefully.
In this guide, you’ll learn the Protection of your cat from fleas, heartworms, ear mites, and intestinal worms with the correct selamectin dosage for cats. Learn safe application, benefits, side effects, and monthly dosing guidelines to keep your cat healthy and parasite-free.
Disclaimer: This content is for informational purposes only and should not replace veterinary advice. Always consult your veterinarian before giving Selamectin or adjusting your cat’s dosage.
Key Takeaways
- Selamectin is a topical medication that treats and prevents fleas, ear mites, heartworms, roundworms, and hookworms in cats.
- Application: Apply to dry, unbroken skin at the back of the neck; do not bathe for 24 hours after application.
- Missed dose: Give the missed dose as soon as remembered and resume the monthly schedule; do not double doses.
- Side effects: Rare; may include hair loss at application site, drooling, vomiting, lethargy, tremors, or itching. Cats with MDR1 mutation may have higher risk.
- Precautions: Use carefully in sick, underweight, pregnant, or lactating cats. Inform your vet about other medications.
- Drug interactions: None documented in cats; generally safe with vaccines, dewormers, and other anti-parasitic treatments.
What is selamectin?
Revolution is an FDA-approved prescription-only topical cat medication containing Selamectin as its active ingredient that is used to control parasites. It is usually used by veterinarians in the treatment, prevention, and control of internal and external parasites.
Revolution (made by Zoetis®) is used to protect cats against:
- Fleas
- Heartworm disease
- Ear mites
- Roundworms
- Hookworms
Since cats are susceptible to parasites all year round, professional recommendations by Companion Animal Parasite Council (CAPC) and Canadian Parasitology Expert Panel (CPEP) highly suggest regular parasite protection in order to ensure that cats are not exposed to fleas, heartworms, and intestinal worms.
How Selamectin works and what it’s used for
After applying selamectin to the skin (usually at the back of the neck), it is absorbed into the bloodstream and distributed throughout the body. This enables it to attack parasites on the skin as well as in the body.
Here’s how selamectin works against different parasites:
- Fleas: Adult fleas are killed when they bite and suck the blood of the cat. It also minimizes the production of flea eggs, which breaks the cycle of life of the fleas in the long run.
- Heartworms: Kills the immature heartworm larvae (carried by mosquitoes) before it becomes a dangerous adult worm that may cause damage to the heart and lungs.
- Intestinal worms: Affects the neuromuscular system of the roundworms and hookworms, which results in paralysis and death to allow the body to eliminate them.
- Ear mites: Kills adult ear mites in the ear canal, and it helps to relieve the itching and irritation within a short time.
Besides control of parasites, research indicates that selamectin may be used to alleviate symptoms of flea allergy which include:
- Skin redness
- Hair loss
- Skin infections
- Itching
Because the flea saliva is a usual allergen, veterinarians tend to prescribe year-round therapy, particularly in cats with allergic skin diseases.
Selamectin Dosage for Cats
The selamectin dosage for cats is generally standardized and based on body weight. It is approved for cats and kittens 8 weeks of age and older, and dosing follows the original guidelines for Revolution.
Recommended Selamectin Dose for Cats (by Weight)
- Cats or kittens ≤ 5 lb → 15 mg vial
- Cats 5.1 lb to 15 lb → 45 mg vial
- Cats 15.1 lb to 22 lb → 60 mg vial
Using the correct selamectin dosage for cats by weight is important to ensure proper protection against parasites while avoiding reduced effectiveness.
Dosing Frequency
For best results, selamectin should be applied once every 30 days. This monthly schedule helps maintain continuous protection against fleas, heartworms, and other parasites.
Important Application Tips
- Selamectin becomes waterproof within 2 hours of application.
- However, it’s best to wait 24 hours before bathing your cat.
- Applying it to wet skin or too soon after a bath can reduce absorption and make the treatment less effective.
Safety Note
This selamectin dose for cats is based strictly on FDA-approved labeling. While some medications may be used off-label in veterinary care, safe and accurate dosing for such uses must always be determined by a veterinarian.
Selamectin Dosage Chart for Cats by Weight
| Cat Weight | Selamectin Dose | ml needed | Application Frequency | Notes / Tips |
|---|---|---|---|---|
| ≤ 5 lb (≤ 2.3 kg) | 15 mg | 0.13 ml | Every 30 days | Apply to dry, unbroken skin at the back of the neck. Wait 24 hours before bathing. |
| 5.1 – 15 lb (2.4 – 6.8 kg) | 45 mg | 0.38 ml | Every 30 days | Ensure the cat cannot lick the application site. Use full contents of the vial. |
| 15.1 – 22 lb (6.9 – 10 kg) | 60 mg | 0.50 ml | Every 30 days | Follow vet instructions for proper administration. Check for side effects after first dose. |
| Over 22 lb (>10 kg) | Consult veterinarian | Consult veterinarian | Every 30 days | Cats above standard weight ranges require veterinary guidance for safe dosing. |
How to give selamectin to cats
Selamectin is a topical cat medication that is applied onto the skin as opposed to being administered orally or through injection. The appropriate dosage of selamectin in cats also implies proper application of the drug in order to make it effective.
How to Apply Selamectin
- Separate the fur of your cat, and put the whole contents of the tube on dry, intact skin at the back of the neck (in front of the shoulder blades).
- Do not rub the drug into the skin.
- Do not touch the area before it is completely dry.
- This place will assist in ensuring that your cat does not lick the product off.
Step-by-Step Administration
- Always ensure that the product is cat approved and is in accordance with the weight and age of your cat.
- Unpack the package and pierce the vial (in the case of products such as Revolution) by pushing the cap, and then take the cap off.
- Apply all the liquid to the skin not fur.
- When applying, it is best to pick a time when your cat is relaxed (resting, eating, or relaxed).
Important Usage Guidelines
- Take selamectin as directed by your veterinarian- do not miss doses or discontinue.
- Should not be used in cats below the age of 8 weeks.
- Do not apply to wet skin or bathe your cat within 24 hrs of application.
- The drug begins to act in 4-8 hours and becomes effective in the first week.
Safety Precautions
- Do not touch your own skin; wash hands after application or put on gloves.
- Should not be used on irritated or broken skin.
- Store in a cool place or away from fire since the product is flammable.
- Should not be used in case your cat is known to be allergic to selamectin or any of its components.
These steps are followed to make sure that the dose of selamectin in cats is absorbed and gives maximum protection against parasites.
What if I Miss Giving My Pet the Medication?
Although you may skip a monthly dose of selamectin in cats by mistake, you may safely resume treatment by administering the dose when you remember. After that, restart your regular monthly schedule.
Example: If a dose was supposed to be given on June 1 but you remember on June 18, give the dose on June 18. The next dose should then be scheduled 30 days later (July 18).
Important Guidelines:
- Do not administer two doses simultaneously. This may augment the threat of side effects.
- When administering selamectin off-label, take it as per the instructions of your veterinarian between doses.
- When you are not sure that you used the right amount of dose the last time, or you still see the fleas on your cat, then call your veterinarian instead of giving an additional dose.
- By keeping cats on the right schedule of selamectin, the cats are constantly protected against fleas, heartworms and other parasites.
Side Effects of Selamectin for Cats
The use of selamectin products is usually safe when taken as prescribed and severe side effects are rare. The medication is well-tolerated by most cats, although one should be aware of possible reactions.
Common and Mild Effects
After application, you may notice:
- Stiff hair, clumping of hair, or powdery residue at the site of treatment (temporary and normal)
- Hair loss at the site of application (approximately 1% of cats) is temporary.
- The product may result in drooling or vomiting when accidentally ingested by licking, typically not because of actual toxicity but because of bad taste.
Rare or Less Common Effects
Other side effects are rare (less than 0.5% of cats in studies) and may include:
- Vomiting
- Diarrhea
- Muscle tremors
- Lethargy
- Loss of appetite
- Erythema or pruritus on the site of application.
More severe reactions have also been reported to the FDA in post-approval reports, but are rare:
- Blisters, excoriations or inflammation on site of application.
- Ineffective balance or incoordination.
- Fever
- Tremors
- Excessive drooling
- Seizures
Genetic Considerations
There are cats that can have a mutation of the MDR1 gene that influences drug reactions. Research approximates that approximately 4 percent of cats in the US can have this mutation. Cats that were mutated with this mutation may experience more severe reactions such as tremors, seizures, or even death. At-risk pets can be tested.
Understanding Side Effects
It is natural that the list of side effects may be frightening, yet not all of the symptoms mentioned are brought about by selamectin. All the symptoms observed are documented in clinical trials and post-marketing reports, regardless of whether they are related to the medication or not. The majority of cats do not have severe problems, and your veterinarian can assist in the calculation of risks and benefits of your cat.
Timing of Side Effects
There are those that can be experienced immediately after taking the first dose and some that can be experienced with time as one continues taking it. In case a symptom arises, your veterinarian will know whether it is actually a result of the medication.
Summary of Potential Side Effects
Side effects that are rare may include:
- Alopecia of the area of treatment.
- Anorexia, vomiting, diarrhea.
- Tremor or incoordination of muscles.
- Itching or redness
- Lethargy
- Excessive drooling
- Seizures (uncommon; more probable in genetically susceptible pets)
Selamectin is a long-acting drug, which has a duration of 4-6 weeks and can be extended in cats with liver or kidney disease.
Risk Factors and Drug Interactions with Selamectin
Although selamectin is mostly safe in cats, there are some risk factors and considerations that influence the use of this product. Knowing these makes your pet safe and the medication is effective.
Risk Factors for Selamectin Use
Selamectin should be used cautiously in cats which are:
- Sick, underweight, or debilitated
- Pregnant or lactating
- Untested about heartworm infection.
Even though the majority of cats are able to tolerate selamectin, genetic mutations may influence sensitivity. Some cats have also been found to have a mutation similar to MDR1/ABCB1 (which has been well documented in dogs). Cats that have this mutation might be more susceptible to severe adverse reactions, and thus your veterinarian might prescribe extra precautions or tests.
Drug Interactions
Selamectin does not interact with any drug in cats. It is safe to use with clinical studies indicate that it is safe to use with:
- Vaccines
- Deworming products
- Other anti-parasitic medications
- Antibiotics
- Steroids
- Topical dips, shampoos or soaps.
Precaution: Selamectin can be used with most drugs, however, it is always important to notify your veterinarian of all supplements, vitamins and prescription drugs your cat is taking.
In dogs (and possibly cats with the MDR1 mutation), the following drugs should be used with caution:
- Cyclosporine
- Diltiazem
- Erythromycin
- Itraconazole
- Ketoconazole
- Spironolactone
- Verapamil
Tips for Safe Use
- Take directions on labels and veterinary advice to the letter.
- Do not self-medicate or mix medications.
- To use off-label, it is only a veterinarian who can decide on safe and appropriate dosing.
- In case of tick control, more recent products such as Revolution Plus have a larger coverage and might eliminate the necessity of several topical applications.
Knowing about risk factors and possible drug interactions, you will be able to use selamectin safely and efficiently and protect your cat against parasites.
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FAQs
What should I do in case of emergency?
If you suspect an overdose or an adverse reaction to selamectin, call your veterinarian immediately. If they are unavailable, follow instructions for contacting an emergency veterinary facility. Be ready to provide your cat’s weight, symptoms, and product information.
What if I miss a dose of selamectin?
If a dose is missed, give it as soon as you remember. Then, continue with your regular 30-day schedule. Do not give two doses at once. If you are unsure whether the previous dose was applied properly, or if fleas are still present, contact your veterinarian for guidance.
How long does it take selamectin to work in cats?
Fleas start dying within 12 hours of application.
Most fleas are killed within 24 hours.
If used preventatively before flea exposure, fleas begin dying within 6 hours, with most dead by 12 hours.
How long can cats take selamectin?
Selamectin can be used year-round for life if your cat tolerates it well. After more than 20 years of use, there is no evidence of reduced effectiveness or increased side effects over time in healthy cats.
Is any monitoring needed with this medication?
No special monitoring is required. Your veterinarian may check that the medication is working, and at home, you should watch for side effects. If any occur, stop use and contact your vet.
How do I store selamectin?
Keep selamectin at temperatures below 86°F (30°C).
Avoid extreme heat or open flames, as it is flammable.
Final Thoughts
Selamectin is a safe and effective monthly topical medication for cats that protects against fleas, heartworms, ear mites, and intestinal worms. When used at the correct selamectin dosage for cats by weight and applied properly to dry, unbroken skin, it provides long-lasting parasite control while minimizing the risk of side effects.
Mild side effects, such as temporary hair loss or drooling, are uncommon, and serious reactions are rare, though cats with the MDR1 gene mutation may require extra caution. Consistent monthly application, proper storage, and veterinary guidance ensure your cat remains healthy, parasite-free, and comfortable.
By following the recommended dosing, administration tips, and safety precautions outlined in this guide, cat owners can confidently use selamectin as a reliable part of their pet’s preventative health care routine.
