Pyrantel is the active ingredient in Drontal® Plus, PRO-Wormer 2® and other dewomers . Side Effects Include vomiting, depression/lethargy, anorexia and over 200 reported deaths
Praziquantel. is the active ingredient in Drontal® Plus.
Side Effects Include vomiting, depression/lethargy, diarrhea & anorexia
Fenbendazole is the active ingredient in most de-worming products: Panacur®, Drontal Plus ®, and Safe-Guard®. Side Effects Include itching, vomiting, depression/lethargy, diarrhea, anorexia and anaphylaxis with over 100 reported deaths.
*An exception to the rule is heartworm medications like Heartguard which are a necessary evil.