Ivermectin + Pyrantel (Heartgard Plus) side effects in dogs
147,644 reports sent to the FDA between 1995 and 2026 involve Ivermectin + Pyrantel in dogs. The most reported problems were vomiting, digestive tract disorder, cardiac disorder. 37% were marked serious, and where it was recorded, signs eased after stopping the medicine in 78% of cases.
About this medicine
Ivermectin prevents heartworm disease (monthly). Pyrantel treats roundworms and hookworms.
Products with this combination include Heartgard Plus, Tri-Heart Plus, Iverhart Plus. The FDA hides brand names in its public data, so these reports cover every product with the same active ingredients.
Some herding breeds (for example Collies) carry the MDR1 gene variant and can be more sensitive to this drug class at high doses.
Most reported side effects
Share = percentage of this medicine's reports that mention the problem. One report can list several problems.
Reports that it didn't work
Some reports are about the medicine not working (for example a dog still getting fleas or heartworm), not about a side effect.
How soon problems started
Time from the first dose to the first sign, where both dates were reported (53,881 reports).
How the animals did
Breeds named most often
Popular breeds appear more often because there are more of them.
- Labrador Retriever 18,477 reports
- German Shepherd Dog 6,258 reports
- Golden Retriever 5,688 reports
- Beagle 3,270 reports
- Boxer (german Boxer) 2,530 reports
- Pit Bull 2,404 reports
- Chihuahua 2,196 reports
- Yorkshire Terrier 2,072 reports
- Shih Tzu 2,048 reports
- Australian Shepherd Dog 1,957 reports