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The Side Effects of Drontal in Cats

| Updated September 26, 2017

The FDA approved Drontal® for use in cats to remove the intestinal parasites hookworms, roundworms and tapeworms. Drontal contains two active ingredients, praziquantel and pyrantel pamoate; praziquantel primarily removes tapeworms, and pyrantel pamoate takes care of hookworms and roundworms. Drontal comes in two forms, pill and injection, and does cause certain side effects. Drontal should not be used in kittens that weigh less than 1.5 pounds and are under 1 month old.


If the cat is allergic to the pill form of Drontal, it may begin to scratch excessively and break out in hives and its face might swell up. Other symptoms of allergic reaction include vomiting and diarrhea, and, in severe cases, the feline might go into shock, suffer from seizures or slip into a coma. The cat's owner might also notice that the cat's gums have turned pale or that its legs are cold.

Digestive Side Effects

Drontal may cause the cat to vomit and have diarrhea even if it's not allergic to the medication. Cat owners might notice other digestive side effects, including a loss of appetite and excessive drooling. These side effects may present themselves in both the pill and injectable form of Drontal.


Both forms of Drontal have been known to make the cat lethargic and disoriented. Cat owners will notice their cat is sleeping a lot and staggering, perhaps as if it were drunk.


Cats receive the injectable form of Drontal in one of two ways: with a shot into the cat's muscle or under the skin (subcutaneous). The feline may experience swelling in the skin and/or muscle area where the shot was administered.