Profender begins killing intestinal worms within hours of application. The active ingredients paralyze parasites on contact, and most worms are expelled through your cat’s stool within 1 to 2 days. You may not see dead worms in the litter box, since they’re often partially digested before being passed.
How Profender Kills Worms
Profender is a topical dewormer applied to the skin on the back of your cat’s neck. It contains two active ingredients that work through different mechanisms to cover a broad range of parasites. One ingredient targets roundworms and hookworms by interfering with their nervous system, causing flaccid paralysis. The paralyzed worms can no longer hold their position in the intestine and get swept out by your cat’s normal digestive movement. The second ingredient targets tapeworms by damaging their outer covering, which causes them to break apart and be digested before they even reach the litter box.
This combination means Profender handles all three major types of intestinal worms cats commonly pick up: roundworms, hookworms, and tapeworms. It also works against multiple life stages of these parasites, not just adults. Studies show 100% effectiveness against mature hookworms, with over 95% efficacy against larval and immature adult stages as well. Against roundworms, clinical trials found fecal egg counts dropped by over 96% after treatment.
What to Expect After Application
Once you part the fur and apply the solution to the skin at the base of your cat’s skull, it absorbs through the skin and enters the bloodstream. The application site needs at least 24 hours to fully absorb. During that time, keep other pets from licking the area and keep children from touching it. Don’t bathe your cat or let the site get wet.
Within the first day or two, your cat should pass the dead or dying worms. With tapeworms, you’ll likely stop seeing the small rice-like segments around your cat’s rear end or in their stool. Roundworms may occasionally appear whole in the stool, though many are digested enough that you won’t notice them. If your cat had a heavy worm burden, you might see a slight change in stool consistency for a day or so as the parasites are cleared.
Common Side Effects
In a clinical study of 606 cats, side effects were uncommon and resolved on their own. The most frequently reported reactions were:
- Licking or excessive grooming at the application site: 3.0%
- Scratching the treatment area: 2.5%
- Drooling: 1.7%
- Lethargy: 1.7%
- Hair loss at application site: 1.3%
- Agitation or nervousness: 1.2%
- Vomiting: 1.0%
Diarrhea, eye irritation, and tremors were each reported in fewer than 1% of cats. The biggest practical concern is making sure your cat doesn’t lick the product off. If ingested, it can cause excessive drooling and vomiting. Applying it high on the back of the neck, right at the skull base, makes it nearly impossible for your cat to reach.
Which Cats Can Use Profender
Profender is approved for kittens at least 8 weeks old and weighing at least 1.1 pounds (0.5 kg). It comes in pre-measured tubes sized by weight range, so you’ll need an accurate weight for your cat to use the correct dose. It’s a single application treatment, meaning one dose handles the current infection. It does not provide ongoing prevention, so reinfection is possible if your cat is re-exposed to parasites through hunting, fleas (which carry tapeworm larvae), or contaminated environments.
For cats with recurring worm problems, your vet may recommend reapplying Profender on a schedule, typically every few months depending on your cat’s risk factors. If you’re treating a tapeworm infection specifically, addressing the underlying flea problem is essential, since fleas are the most common way cats pick up tapeworms again.
Signs the Treatment Worked
The clearest sign Profender did its job is the disappearance of symptoms. If your cat had visible worm segments, a potbellied appearance, changes in appetite, or loose stools, these should improve within a few days to a week. A follow-up fecal exam two to four weeks after treatment can confirm the parasites are gone by checking for eggs in the stool. This is especially useful for roundworms, where egg counts dropped by 96% or more in clinical trials but didn’t always hit zero, meaning a small number of cats may need a second treatment.