When you think about your furry canine companion, worms are probably the last thing on your mind. But the truth is that dogs can get infested with parasites like roundworms, hookworms, and whipworms. These parasites live inside a dog’s intestines and feed off its food while causing a variety of health problems in pets.

Fortunately, deworming medications (“dewormers”) can help rid your pup of these pesky critters. Let’s learn more about this important topic or contact your veterinarian for help if you’re concerned.

Administering dewormer to a dog that doesn’t have worms is generally considered safe and might even be recommended by veterinarians as a preventative measure in some cases. Many deworming medications are broad-spectrum, targeting a range of potential parasites, and are given routinely to dogs to ensure any early-stage or low-level infestations are addressed before becoming problematic.

How Do They Work In A Dog’s System?

Deworming medications target specific parasites by disrupting their life cycle or attacking their nervous system. The exact mechanism of action varies based on the type of dewormer. For instance:

  • Praziquantel, used for tapeworms, causes paralysis and damage to the parasite’s skin internally, allowing it to be digested and eliminated through the dog’s system.
  • Fenbendazole targets a variety of worms, including roundworms, hookworms, and whipworms, by inhibiting the worms’ ability to consume nutrients, leading to their death.
  • Ivermectin, another common ingredient, paralyzes and eventually kills parasites by amplifying the release of a neurotransmitter.

Once the dewormer has incapacitated or killed the parasites, the dog’s body naturally expels them, usually through feces. During and after the deworming process, it’s not uncommon to see evidence of worms in a dog’s stool, as they are expelled from the body.

Possible Side Effects of Unnecessary Deworming In Dogs:

While routine deworming is common practice to keep dogs parasite-free, administering dewormers without the presence of a worm infestation, especially if done frequently or inappropriately, may expose your dog to unnecessary risks. Here are some potential side effects of unnecessary deworming:

Gastrointestinal Disturbances:

  • Nausea
  • Vomiting
  • Diarrhea

Neurological Symptoms:

  • Tremors
  • Ataxia (unsteady or uncoordinated movement)
  • Seizures (in rare cases)


The dog may seem unusually tired or uninterested in activities.


Increased drooling or salivation can be an adverse reaction.

Skin Reactions:

  • Rashes
  • Itching
  • Swelling at the administration site (if the medication is given topically)

Loss of Appetite:

Some dogs might refuse to eat or eat less than usual after being dewormed.

Weight Loss:

This can be a result of loss of appetite or gastrointestinal disturbances.

Respiratory Symptoms:

Coughing or difficulty breathing, though rare, can occur.

Development of Resistance:

Overusing deworming medications can lead to parasites developing resistance, making future infestations harder to treat.

Allergic Reactions:

Though rare, some dogs can have an allergic reaction to a deworming medication.

The Role of Routine Vet Check-ups – Preventing Overuse of Dewormers:

Routine vet check-ups play a crucial role in the overall health and well-being of dogs. One of the benefits of these visits is the prevention of unnecessary medication, including dewormers.

Regular fecal exams can detect the presence of worm eggs, ensuring that dewormers are only used when needed. Moreover, veterinarians can advise on the local prevalence of certain parasites and recommend appropriate preventative measures, which can be more effective and safer than overusing dewormers.

Misconceptions About Deworming – Debunking Common Myths:

“All Dogs Need Monthly Deworming”:

While some dogs, especially puppies, might benefit from more frequent deworming schedules, not all dogs require monthly treatments. The frequency should be based on the dog’s risk factors and local parasite prevalence.

“Indoor Dogs Don’t Need Deworming”:

Even dogs that predominantly stay indoors can be at risk. They can still be exposed to parasites during short outings or through other animals and pests that enter the home.

“If I Don’t See Worms, My Dog Isn’t Infected”:

Many internal parasites are tiny or microscopic. A dog might be infested even if you don’t see any worms in their feces.

“Over-The-Counter Dewormers Are Just As Effective”:

Not all dewormers are created equal. Some OTC products might not be as effective, or they might not target the specific parasites affecting your dog.

Proper Use of Dewormers – Ensuring The Health And Safety of Your Dog:

For the health and safety of your dog, it’s essential to use dewormers appropriately:

Consult A Veterinarian:

Always seek advice from a vet before administering any deworming medication. They can provide guidance on which product to use, appropriate dosing, and frequency.

Follow Dosage Recommendations:

Overdosing can lead to adverse side effects, while underdosing might not effectively treat the infestation.

Monitor for Side Effects:

After administering a dewormer, watch your dog for any signs of adverse reactions or side effects, such as vomiting, diarrhea, lethargy, or unusual behavior.

Keep Records:

Maintain a record of all deworming treatments, including dates, products used, and dosages. This helps ensure that treatments are given at appropriate intervals and aids in tracking any potential issues.

Regular Fecal Examinations:

Have your dog’s feces examined regularly, especially if they’re at higher risk for parasites. This can provide early detection and treatment of infestations.

Environmental Control:

Reduce the risk of parasite infestations by keeping your dog’s environment clean. Regularly clean and disinfect living areas and promptly remove feces.

By understanding the importance of routine vet visits, debunking deworming myths, and ensuring the proper use of dewormers, dog owners can maintain the health and safety of their furry companions.


To sum things up, if you give a dog a dewormer and they don’t have worms, it may not be the answer to everything. You may just end up with an unhealthy pup, experiencing side effects from unnecessary medication.

Therefore, it is crucial to take them to a trusted vet if there are any signs of worms or other diseases in order to receive the correct diagnosis and treatment before taking matters into your own hands. Take all necessary precautions for proper pet care so that your pup can live its happiest and healthiest life! If you ever have questions or concerns about illnesses or prevention tactics for worm infestations, consult with a professional veterinarian.

Delia Mason
I am Delia Mason, the owner of Dogsshelf, and take pride in providing the most comprehensive information possible on dog foods, collars, bowls, and other dog-related items. This website is dedicated to helping dog owners make sound decisions when it comes to their furry friends. That's why I only recommend products that I would use myself and have extensively researched to make sure they're the best of the best.