Side Effects of Dewormers

There are several types of dewormers, some of which target specific worms or intestinal parasites and others that target a variety of them. Side effects are more common among dewormers that target more than one type of worm. These dewormers, called broad spectrum wormers, contain multiple ingredients that force the worms out of your pet's system.

  1. Excessive Salivation

    • Excessive salivation is one of the most common side effects of dewormers. This problem should pass within an hour or so after administering the medication. Make sure plenty of fresh, clean water is available to your dog.

    Nausea and Vomiting

    • Nausea and vomiting, though rare, are reported side effects of almost every dewormer on the market. The chemicals may cause these effects in an attempt to rid your dog's body of the parasites.

    Diarrhea

    • Diarrhea is another rare side effect, but one that should not cause alarm. Again, this is just the medication doing its job to rid your dog of internal parasites.

    Warnings

    • Most products are not advised for use in dogs that are nursing or pregnant. Seek veterinary advice before administering over-the-counter dewormers to pregnant dogs, as well as dogs that are ill or have a compromised immune system.

    Severe Adverse Reactions

    • In clinical trials of dewormers, no severe adverse reactions were reported. If you suspect your pet is having an adverse reaction to a dewormer, seek emergency veterinary care immediately. Symptoms of an adverse reaction can include seizure, lethargy, loss of appetite or coma. In some cases, death can occur.