Get

In Your Inbox

Catster is reader-supported. When you buy via links on our site, we may earn an affiliate commission at no cost to you. Learn more.

How Long Will My Cat Have Diarrhea Once They’ve Been Dewormed? Vet Reviewed Facts

Share

cat litter box

Deworming is a necessary treatment for cats infested with parasites. Parasites are common in cats as they can be spread in various ways, depending on the type. Thankfully, the treatment is safe and effective and only sometimes causes a day or two of uncomfortable symptoms like vomiting and diarrhea. After these signs resolve, your cat will feel a lot healthier.

Keep reading to learn more about the most common parasites found in cats, how to spot the symptoms, and what to expect from deworming.

divider 3 paws

Types of Parasites in Cats

Before deworming, your vet must first identify the type of parasite1 your cat is struggling with. If the wrong deworming medicine is used, it may be ineffective.

Tapeworms

Tapeworms are one of the most commonly found parasites in cats. Although they should still be treated, they rarely cause serious concerns in adults. However, they can be dangerous for kittens and lead to slow growth or permanent stunting. They must be transmitted by an intermediate host, meaning that another creature needs to transfer them to the cat. In most cases, the host is a flea.


Roundworms

Roundworms are another parasite that can severely affect a kitten’s ability to grow. They’re easily passed through the feces of another infested host They usually cause severe digestive upset and a noticeably bloated belly.


Hookworms

Hookworms can be the most dangerous parasite because they latch onto the intestinal wall and feed on the cat’s blood. If the infestation is severe or lasts a long time, it can lead to anemia which can be life-threatening.

cats roundworms
Image Credit; Todorean-Gabriel, Shutterstock

divider 3 paws

Signs of Worm Infestation

Deworming kittens is standard practice, even if there are no signs of them yet. That is because many kittens have them, and it’s safe to assume yours will too. This safety measure ensures your cat continues growing long before you notice any outward signs that they have worms.

Knowing the potential signs of worms in older cats is essential to get them treated as soon as possible before severe health complications like anemia or malnutrition occur. What are the signs of a worm infestation in cats1?

  • Weight loss
  • Change in bowel habits
  • Visible worms in feces or around their anus
  • Dragging their bottom on the carpet
  • Lethargy
  • Course or dull fur

divider 3 paws

The Deworming Process

Your veterinarian will need a stool sample to check for the presence of worms and determine how to treat the parasites1 based on what kind they are. This will help them choose the best deworming medication to use. They may also prescribe a drug that fights several types of worms.

Depending on the type and severity of the infestation, they will administer the initial dose at the clinic with instructions to return for additional ones or send you home with medication to administer yourself on a precise schedule. This is because a dewormer may not remove the parasite larvae. Larvae will hatch into worms, which must be treated with a second or third dose. Be sure to follow your vet’s instructions to ensure your cat is completely free of parasites.

tired sick cat lying on bed
Image Credit: Natata, Shutterstock

divider 3 paws

Deworming Side Effects

Because these medications are designed to flush out harmful parasites in your cat, you can potentially expect some deworming side effects1. Vomiting and diarrhea usually stop within 24 hours but may take up to 3 days to fully resolve.

If you are ever concerned about your cat’s reaction, notify your vet. They may suggest an over-the-counter remedy for diarrhea.

vet deworming cat at the clinic
Image Credit: bdavid32, Shutterstock

divider 3 paws

Cat Worms & Humans

Some cat parasites can be transmitted to humans but typically affect us differently. For example, hookworms usually burrow under the skin and cause intense itching that may lead to infection.

Children and those with compromised immune systems, including the elderly, may be more susceptible to feline parasites. Cats showing signs of a parasite infestation should be treated as soon as possible, and precautions should be taken to disinfect the home1 to prevent the transfer to humans.

divider 3 paws

Parasite Prevention

Thankfully, there are steps you can take to prevent worms1. This avoids the hassle of treating worms and gives you peace of mind that your cat will remain healthy and happy. Because fleas spread common parasites, proper flea prevention is vital. Some flea management medications also protect against worms and even ear mites. If you have an outdoor cat, you may want to have them dewormed as a precaution on a regular schedule to keep from spreading worms to other pets and people in the home.

We recommend you consult a veterinarian for the best advice on which would be the best treatment for your cat.

If you need to speak with a vet but can't get to one, head over to PangoVet. It's an online service where you can talk to a vet online and get the advice you need for your pet — all at an affordable price!

Preventative wellness PGV mention keep cat healthy Preventative wellness PGV mention keep cat healthy mobile

divider 3 paws

Conclusion

If you have a kitten that has not yet been dewormed, you should keep them isolated from other pets and give them their litterbox to ensure they don’t spread parasites. Even adult cats are not immune to worms, however. Cats showing signs of worms should see their vet as soon as possible. Because these medications are safe and effective, deworming can be done to treat an active infestation of worms or as a preventative measure to keep from transmitting them.

Whatever the reason for deworming, it’s essential to know that any side effects your cat experiences, like diarrhea, will be short-lived and well worth the benefits of the treatment. Be sure to deworm your kitty only with the guidance of a veterinarian.


Featured Image Credit: Lightspruch, Shutterstock

Want content like this delivered to you?

Sign Up For Our Newsletter

News, insights, expert advice, and everything cat

* By submitting, you agree to our Terms & Conditions and Privacy & Cookies Policy.




How useful was this post?

Click on a star to rate (you can leave written feedback after clicking submit)

Help us improve Catster for pet parents!

Your feedback really matters.

What did you like about this post? Also how can we improve it?

Join the conversation

Leave a Reply

You’re very welcome to leave a comment or question. Please know that all comments must meet our community guidelines, and your email address will NOT be published. Let’s have a positive and constructive conversation.


Talk With A Vet Online

Peace of mind,
anywhere, anytime

Affordable vet advice

Do Cats Cause Schizophrenia? Scientists Find a Link – Here’s What It Means

Being a fierce advocate (and occasional recipient of) mental health support and awareness, the term ‘crazy’ is not one I like to fling...

One in 100 Cats Gets Diabetes – Here’s How to Catch It Early

One in every 100 cats develops diabetes.1 That’s not a rare, unlucky condition reserved for cats with obvious health problems. It’s common enough...

Dramatic Rescue Turns Into Dramatic Reunion

What started as a routine call for the RSPCA became a heroic, five-hour rescue featuring one trapped and traumatized cat, an emotional family...

Ask Dr. Paola – Help! How Do I Know if it’s Ear Mites! (May 4, 2026)

Welcome to our “Ask Dr. Paola” series, where every Monday we bring expert advice straight from Dr. Paola Cuevas (MVZ) to help our...

More related

Siberian Cat Grooming: 4 Vet-Approved Tips & Tricks

Siberian cats have long, thick coats, and it’s necessary to maintain their coat as part of keeping your cat healthy and happy. Coat...

9 Ways Kids Can Raise Money to Help Cats: Fun & Creative Ideas

Any cat owner will tell you their pets are valued like family members because that’s exactly what they are. Unfortunately, not all cats...

How to Get Rid of Cat Spray Smell: 6 Tips & Home Remedies

Cat spray smell is a common problem for many pet owners, as our feline friends can develop a bad habit of urinating outside...

Will Cat Conjunctivitis Go Away by Itself? Vet-Verified Facts & Info

There are a variety of eye infections and issues you may see in your cat throughout their life, and conjunctivitis is one of...

Keep reading

Horner’s Syndrome in Cats: Our Vet Explains Signs, Diagnosis & Management

The neurologic system is a complex network of nerves, signals, and responses. When something goes wrong or there is an injury within the neurologic system, physical abnormalities can be seen. Such is the case with Horner’s syndrome, a collection of...

Cat with eye infection looking at camera

How Many Calories Should a Cat Eat? Vet-Reviewed Cat Feeding Guide

All cats have individual dietary needs based on their breed, size, age, and health conditions. As notoriously picky eaters, finding the right food for them is only half the battle. Feeding your cats the appropriate amount is a crucial aspect...

Blue hepper NomNom 4

Can Cats Eat Raw Pork? Vet-Reviewed Facts & FAQ

Raw diets for pets have become all the rage within the last decade or so, with many people attempting this diet at home on their own without guidance from a veterinarian or a veterinary nutritionist. Many people tout the benefits...

Can Cats Eat Raw Pork

Why Do Cats Lick You? 6 Vet-Approved Possible Reasons

Cats are notoriously aloof little critters, so it’s hard not to feel like the chosen one when yours licks you. But what’s the real reason cats lick their humans? Is it a way to show affection, or is something more...

cat-licking-owners-face

What Kind of Toys Do Blind Cats Like? 4 Vet-Reviewed Types & Suggestions

If you find yourself the proud owner of a blind kitty, it can feel like there are a whole host of things that you need to navigate carefully, like toys. You want to get toys that they’ll love, but you...

blind calico cat

How to Get My Cat to Stop Begging for Food at Night: 8 Vet-Approved Tips

Is your cat constantly begging for food at night? Maybe it’s the early evening when you’re still awake, or perhaps you’re dead asleep and their meowing and pawing is waking you up. Either way, it’s beyond annoying. Making it even...

Calico cat standing up begging for treat asking for food scratching leg looking up

Why Are My Cat’s Gums Red and Swollen? 8 Possible Reasons & What to Do

Owning a cat has its ups and downs, and unfortunately, most of the downs occur when our pets are sick. When your cat has dental issues, it can sometimes indicate an underlying health problem. Either way, dental complications can have...

Cat with red, swollen an inflamed gums or resorption of teeth in felines and gingivitis showing teeth

6 Best Cat Calming Treats in 2026 – Reviews & Top Picks

Sometimes our felines can be nervous Nellies, while others can be downright aggressive. Regardless of why you need calming supplements for your cats, you might not be too keen on the idea of pills. It can be tricky with cats...

cat_pasja1000, Pixabay

Love Cats? So Do We! Join the Catster Community

Stay informed with expert pet care insights delivered straight to your inbox! Discover professional guidance on animal behavior, feeding tips, trusted product picks, and much more.




Sign up for the Catster Email Newsletter

Stay informed with expert pet care insights delivered straight to your inbox! Discover professional guidance on animal behavior, feeding tips, trusted product picks, and much more.