Constipation after Pyrantel in dogs

The FDA has received 24 reports of constipation in dogs after Pyrantel. That is 0.5% of all reports for this medicine, compared with 0.2% across reports for all dog medicines, so it is reported unusually often with this medicine.

24Reports

29%Marked serious

17%Recovered

17%Died or euthanised

Same dayTypical onset

How soon it started

Same day

6 60%

1–2 days

3 30%

3–7 days

0 0.0%

1–4 weeks

0 0.0%

Over a month

1 10%

How the animals did

Recovered

4 17%

Still unwell when reported

3 13%

Died

4 17%

Not known

13 54%

Problems reported at the same time

10 42%

7 29%

6 25%

4 17%

4 17%

Distension of abdomen

3 13%

Seizures

2 8.3%

Blood in faeces

2 8.3%

Age of the animals

Under 1 year

1–3 years

4–7 years

8–11 years

12+ years

About this medicine

Pyrantel treats roundworms and hookworms.

Questions owners ask

Can Pyrantel cause constipation in dogs?: 24 reports link the two, but a report alone does not prove the medicine was the cause: other illnesses, other medicines or coincidence can be involved. Your vet can judge it for your animal.
How soon after a dose was it reported?: In half of the reports with dates, it started within the same day of the first dose.
What should I do?: Don't give another dose until you've spoken to your vet, and keep the packaging so you can tell them the product and dose. Your vet can also report it to the FDA (or you can, through the manufacturer or FDA form 1932a).

Constipation with similar medicines

Constipation after Pyrantel + Sarolaner (Simparica Trio) 42 reports · 0.1% of its reports
Constipation after Febantel + Praziquantel + Pyrantel (Drontal Plus) 28 reports · 0.4% of its reports
Constipation after Fenbendazole 44 reports · 0.7% of its reports
Constipation after Praziquantel + Pyrantel 41 reports · 1.1% of its reports

All reported side effects of Pyrantel in dogs · Medicines most reported with constipation