Types of Dewormers for Dogs and Dosing Schedules

DigestivePreventionMeongsiljang Veterinary Advisory Board

We’ve compiled a veterinary-backed guide to dewormers that prevent common intestinal parasites in dogs—roundworms, hookworms, whipworms, and tapeworms—including the types of dewormers, age-specific dosing schedules, and proper administration methods.

Why Should You Deworm Your Dog Regularly?

Illustration of a puppy protected by a deworming shield for healthy care

Deworming should begin at two weeks of age and continue at least every three months once the dog reaches adulthood. The most common intestinal parasites in puppies are roundworms, hookworms, and whipworms. These three are the most frequently occurring parasites in dogs, and since tapeworm infections are also possible, they require concurrent management. These parasites can cause diarrhea, vomiting, weight loss, and anemia, and can even be life-threatening, especially in young puppies. Regular deworming is a fundamental aspect of health care that not only safeguards your pet’s well-being but also protects the hygiene of your entire household.

Get a Fecal Exam Before Administering Dewormers

If you’re starting deworming for the first time or haven’t administered it in a long while, have your pet undergo a fecal exam at a veterinary clinic first. Identifying the specific parasite is essential to selecting the most appropriate medication. This is especially important for puppies under 8 weeks of age, as treatment options are limited; be sure to consult with your veterinarian.

Four Common Intestinal Parasites in Dogs

These are the most common intestinal parasites that affect dogs.

Roundworms: The most prevalent parasite in dogs. Puppies are often infected in utero via the placenta or through their mother’s milk, meaning they may be born with the infection. They can also become reinfected by licking or swallowing eggs from contaminated soil. Symptoms include a pot-bellied appearance, vomiting, and diarrhea.

Hookworms: These attach to the intestinal wall and feed on blood. According to veterinary internal medicine textbooks, severe cases can cause life-threatening anemia, posing a particular risk to young puppies.

Whipworms: Residing in the large intestine, they cause chronic diarrhea and bloody stools. Because their eggs survive for long periods in the environment, reinfection is frequent.

Tapeworms: Infected dogs may exhibit scooting or rubbing their rear end on hard surfaces. Symptoms can include diarrhea, loss of appetite, and weight loss. If you notice small, white, rice-grain-like segments around the anus, suspect a tapeworm infection.

Illustration of four common intestinal parasites in dogs

Oral Dewormers — The Fundamental Medication

Fenbendazole: This is a broad-spectrum dewormer effective against roundworms, hookworms, and whipworms. It is introduced in veterinary pharmacology textbooks as one of the most fundamental deworming ingredients. Your veterinarian will determine the dosage and duration of treatment based on your pet’s weight.

Pyrantel pamoate: This ingredient is effective against roundworms and hookworms. Because it can be used from two weeks of age, it is commonly used for the first deworming of young puppies.

Praziquantel: This is a deworming ingredient specifically for tapeworms. If tapeworms are confirmed through a fecal examination, your veterinarian will prescribe medication containing this ingredient.

Combination Dewormers — Managing Multiple Parasites at Once

In recent years, combination dewormers containing multiple active ingredients have become widely used.

Milbemycin combinations: These products prevent heartworm disease while simultaneously treating roundworms, hookworms, and whipworms. Administered once a month, they provide broad-spectrum control of internal parasites.

Moxidectin combinations: Available as a topical spot-on treatment, these products address heartworm prevention, roundworm and hookworm treatment, and external parasite control all in one application.

Many heartworm preventatives also include deworming properties. If your pet is already on a heartworm preventive, a separate dewormer may not be necessary. Learn more about the types of heartworm preventatives and dosing guidelines here: Types of Heartworm Medications and Dosing Guide.

An illustration of a broad-spectrum dewormer that manages multiple parasites simultaneously.

Comparison of Dewormer Ingredients

Compare the key features of each deworming ingredient at a glance in the table below.

Ingredient	Target Parasites	Administration Form	Features
Fenbendazole	Roundworms, hookworms, whipworms	Oral	Broad-spectrum dewormer; standard prescription
Pyrantel	Roundworms, hookworms	Oral	Safe for use from 2 weeks of age
Praziquantel	Tapeworms	Oral	Specialized ingredient for tapeworms
Milbemycin	Roundworms, hookworms, whipworms	Oral	Also prevents heartworms
Moxidectin	Roundworms, hookworms	Spot-on	Simultaneously manages external parasites

Deworming Schedule by Age

The deworming schedule for dogs varies depending on their age.

2–12 weeks old: Administer every two weeks. This is the critical period for quickly eliminating parasites that may have been transmitted from the mother.

12 weeks to 6 months old: Administer once a month. Since their immune systems are not yet fully developed, frequent management is necessary.

Adult dogs (6 months and older): The standard minimum is once every three months. If your dog spends a lot of time outdoors or lives in a multi-dog household, consult your veterinarian to adjust the schedule accordingly.

When using heartworm combination preventatives: If you are using a monthly combination product, intestinal parasites are automatically managed alongside heartworm prevention, so no separate deworming schedule is needed.

Illustration of deworming schedules for dogs by age

Consult Your Veterinarian in These Situations

For pregnant or nursing dogs, the deworming ingredients that can be safely used are limited. Administering medication without veterinary guidance may harm the developing puppies. If you see parasites in your dog’s stool after deworming, it means the medication is working effectively. Don’t be alarmed—simply follow the recommended schedule for any additional doses. However, if vomiting or diarrhea becomes severe, it could indicate an adverse reaction to the medication, so contact your veterinarian right away.

Reviewed by a veterinarian

Dr. Tony — Punnawat Phongkittirak

Veterinarian

A veterinarian who majored in veterinary medicine at Khon Kaen University, Thailand, and completed the IVSA program at North Carolina State University in the United States. Drawing on clinical experience at animal hospitals, he works in the pet healthcare field and is dedicated to building a digital care environment that connects pet parents with veterinarians.

Frequently Asked Questions

Do I need a prescription from the vet to get deworming medication?

While general dewormers are available at pet pharmacies, using the wrong medication can be ineffective if you don’t know which parasite is causing the infection. For first-time treatments, the most reliable approach is to have your pet undergo a fecal exam and receive a prescription from your veterinarian.

After giving my pet dewormer, I noticed parasites in their stool. Is this normal?

Yes, that’s normal. The medication paralyzes or kills the parasites, which are then expelled in the stool. Roundworms may appear as long, noodle-like strands. Simply administer the next dose according to the recommended schedule.

I’m already giving my pet heartworm prevention. Do I still need to give a separate dewormer?

If your heartworm preventive contains milbemycin or moxidectin, it also protects against roundworms and hookworms. However, some products do not cover tapeworms or whipworms, so ask your veterinarian to confirm the full spectrum of worm protection provided by the medication your pet is currently taking.

Do indoor dogs that don’t go for walks also need deworming?

Yes, it is necessary. Parasite eggs can be brought in on your shoes or clothing, and pets can become infected with tapeworms through fleas. Even for indoor dogs, we recommend deworming at least once every three months.

Can I give my dog human deworming medication?

Absolutely not. Human medications are not formulated for dogs and can cause serious side effects depending on their ingredients. Always use dewormers specifically designed for animals.

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References

[1] Clinical Medicine of the Dog and Cat, 4th Ed — Gastrointestinal Parasites, Hookworms, Roundworms

[2] Plumb's Veterinary Drug Handbook, 10th Ed — Fenbendazole, Pyrantel, Praziquantel, Milbemycin

[3] Blackwell's Five-Minute Veterinary Consult Clinical Companion, Small Animal Toxicology, 3rd Edition — Anthelmintics

[4] Notes on Canine Internal Medicine, 4th Ed — Intestinal Parasites, Treatment