Cat Throwing Up Worms? Here’s What It Really Means And What To Do

When you purchase through links on our site, we may earn a commission at no extra cost to you. Learn more.

You were ready for a hairball. You got a horror show. Out of nowhere, your cat is throwing up worms.

One minute, your cat is gagging; the next, something long and wiggly hits the floor. If you’ve just witnessed your cat vomit an actual worm, first, take a deep breath. Second, keep reading.

It’s okay to freak out a little, seeing a worm come out of your cat’s mouth is nightmare fuel. But you’re not a bad cat parent. This is more common than you think, and it’s absolutely treatable.

Let’s Hear it From A Veterinarian: Why is my Cat Throwing up Worms?

I sat down with Dr Rebecca MacMillan, BVetMed BSAVA PGCertSAM MRCVS, to get a clinical perspective on why cats throw up worms.

If a cat is throwing up worms, it means they probably have a very high parasite burden. Large numbers of worms may irritate the digestive tract enough to trigger vomiting. This is an uncommon scenario, as most worms remain unnoticed inside your cat, producing eggs that are shed in the cat’s faeces. It is most likely to be seen in stray cats or kittens that haven’t received any anti-parasite treatments.

It is essential to take your cat to a veterinarian so that an effective worming product can be administered. They will also be checked over for any other health issues that could be contributing to their vomiting.

Most worms in cats go under the radar; it’s rare we actually get to see them! Following a worming treatment, I have sometimes seen dying worms vomited up or passed out in the stools, but not often. Most of these worms have come from kittens who have had a poor start in life and have not received any anti-parasite products previously. Maybe I would see more cases if I worked in a charity setting rather than private practice, however.

– Dr Rebecca MacMillan, BVetMed BSAVA PGCertSAM MRCVS

Why Vomiting Means Parasite Migration

When a worm burden gets heavy, parasites can begin to migrate through the body. Roundworms, for example, may travel through the bloodstream and reach the lungs or stomach. Once in the stomach, the body responds by trying to expel them through vomiting.

According to the Merck Veterinary Manual, gastrointestinal parasites in cats can cause vomiting, diarrhea, weight loss, and poor coat condition, especially when infestations are severe. In some cases, worms may be visible in the vomit or stool, which is a sign that the parasite burden has reached a critical level requiring veterinary intervention.

So no, your cat did not just eat a worm and immediately throw it up. That worm likely hatched inside your cat, moved through their system, and ended up being expelled after triggering a physical reaction.

Is It Always an Emergency?

Vomiting a worm is not necessarily an after-hours emergency, but it is urgent. It means your cat has a confirmed parasitic infection, and possibly a significant one. There may be health risks beyond just digestive upset, and some parasites, like roundworms or hookworms, can infect humans as well.

In rare cases, worm levels could be so high that they obstruct the digestive tract. This blockage is an emergency situation that could require surgery to resolve. Lots of worms could also irritate your cat’s stomach and intestines, leading to vomiting, diarrhea, and malnutrition. Death is a possible outcome in severely affected kittens

– Dr Rebecca MacMillan, BVetMed BSAVA PGCertSAM MRCVS

You should contact your veterinarian as soon as possible. A fecal test, proper diagnosis, and targeted treatment are important not only for your cat’s health but for the safety of your household.

Common Worms That Cats May Vomit

Not all worms are equal when it comes to showing up in your cat’s vomit. Some are far more likely to make an appearance than others. Here’s a breakdown of the most common culprits and what you need to know about each.

Roundworms (The Usual Spaghetti Suspect)

The most common type of worm to be vomited up is the roundworm (Toxocara cati or Toxascaris leonina). These worms are white or cream-coloured and spaghetti-like in appearance. They can sometimes grow quite large. If your cat is vomiting worms, it is a sign that they have a high number in their system, which could be affecting their health.

– Dr Rebecca MacMillan, BVetMed BSAVA PGCertSAM MRCVS

Cats can get roundworms by:

• Eating infected prey like mice or birds
• Ingesting contaminated soil or feces
• Nursing from an infected mother

According to the Cornell Feline Health Center, most cats become infected by ingesting worm eggs in contaminated soil, prey, or feces.

Once inside the cat, the roundworm eggs hatch in the intestines, and the larvae may migrate through the liver and lungs before returning to the digestive tract. In cases of heavy infestation, some roundworms may make their way to the stomach and be vomited up.

Tapeworms (The Flea-Tagalong Segments)

Tapeworms are segmented parasites that are more often seen in feces than vomit, but in cases of severe infestation, they can be thrown up as well. Instead of a long, noodle-like shape, tapeworms are flat and made up of many small segments that look like rice grains.

Tapeworms often infect cats through flea ingestion. When a cat grooms itself and swallows a flea carrying tapeworm larvae, the parasite can develop in the intestines. Vomiting them is rare but possible if the worm burden is significant.

You might also find dried tapeworm segments around your cat’s anus, in the litter box, or on bedding.

Less Common Types (Hookworms and Others)

Hookworms and other intestinal parasites are less likely to appear in vomit, but are still worth knowing about. These worms typically stay in the small intestine and feed on blood, causing anemia and digestive issues.

While hookworms are usually diagnosed through fecal testing rather than visible signs, they can be just as harmful, especially to kittens or immunocompromised cats.

If your cat is vomiting and showing other symptoms like weight loss, bloody stool, or lethargy, your vet may test for multiple types of parasites, even if nothing is visibly present.

How Cats Get Worms

Even the cleanest, most pampered cat can end up with worms. Parasites are persistent, and the ways cats pick them up are surprisingly common. Understanding how infection happens is key to prevention.

Hunting and Eating Prey

Cats are natural hunters. Whether it’s a mouse, bird, or insect, any prey animal can be carrying worm larvae. When your cat eats the infected prey, the parasites move in. Outdoor cats are at much higher risk, but even indoor cats can hunt bugs or lizards that sneak inside.

Fleas and Accidental Ingestion

Fleas are more than just an itchy nuisance. They are the main carriers of tapeworm larvae. When your cat grooms and swallows an infected flea, something that can happen in a split second, the tapeworm larvae are released into the digestive tract, where they grow and reproduce.

Contaminated Soil, Litter, or Surfaces

Roundworm and hookworm eggs can live in soil or on surfaces like litter boxes, porch steps, or dirty floors. A cat doesn’t need to eat anything unusual to get infected; stepping in contaminated material and then grooming their paws is often enough.

From Mother to Kitten

Kittens can be born with worms or pick them up shortly after birth through their mother’s milk. That’s why deworming protocols are especially important for young kittens and pregnant queens.

Other Signs Your Cat Might Have Worms

A worm in vomit is an obvious red flag, but many cases of worm infestation are far more subtle. Knowing what to look for can help you catch a problem early, before it becomes serious.

Subtle Symptoms You Might Miss

1. Weight loss despite normal or increased appetite
2. Bloated or pot-bellied appearance (especially in kittens)
3. Dull or patchy coat
4. Diarrhea or constipation
5. Scooting or excessive licking of the rear
6. Lethargy or general “off” behavior

These symptoms may come and go or be easy to dismiss as minor issues, which is why parasites often go undetected for too long.

My Cat Vomited Worms: What Do I Do?

It’s disturbing, but don’t freeze or panic. Taking the right steps quickly can make all the difference. Here’s exactly what to do next.

Take a Photo or Sample

As unpleasant as it sounds, try to preserve the evidence. Either snap a clear photo of the worm or collect it in a sealed plastic bag (using gloves or a tissue). This helps your veterinarian identify the type of parasite and determine the best treatment.

Call Your Vet Immediately

This is not something to monitor over time. Vomiting a worm indicates a significant parasite load and possibly a systemic infection. Contact your vet as soon as possible for guidance. They may recommend bringing your cat in right away or scheduling an appointment within the next day or two.

Testing and Diagnosis

Your veterinarian will typically run a fecal flotation test to identify worm eggs or larvae. Sometimes, further diagnostics like blood work or imaging are needed if symptoms suggest more serious internal migration. If you have other pets, they may recommend testing them too, since many parasites are contagious between animals.

Treatment and Follow-Up

Once the worm type is identified, your vet will prescribe a specific deworming medication. Over-the-counter options are often ineffective or only partially treat the problem. Some treatments require multiple doses spaced weeks apart to fully eliminate the parasite lifecycle. Always follow the full course, even if symptoms improve quickly.

Your vet may also advise a follow-up fecal test in a few weeks to confirm the infection is fully resolved.

Most of the time, seeing the worm is enough evidence that there is a problem and indicates the cat needs urgent de-worming. Fecal samples can help to identify and confirm if worm eggs are present in your pet’s stools, but many owners will just administer a routine worming treatment regularly. This could be a tablet or a spot-on medication. It is always best to use a vet-approved product, at the correct dose, so that its effectiveness is guaranteed.

Most worms in cats go under the radar; it’s rare we actually get to see them! Following a worming treatment, I have sometimes seen dying worms vomited up or passed out in the stools, but not often. Most of these worms have come from kittens who have had a poor start in life and have not received any anti-parasite products previously

– Dr Rebecca MacMillan, BVetMed BSAVA PGCertSAM MRCVS

Hygiene Tips for Your Home

Parasite eggs can linger on surfaces, especially in areas your cat frequents. To help prevent reinfection:

• Clean the litter box daily and disinfect it regularly
• Wash your cat’s bedding and blankets in hot water
• Vacuum carpets and upholstered furniture thoroughly
• Wash your hands after handling litter, food bowls, or your cat
• Keep children and other pets away from contaminated areas until cleaned

You will need to take care to protect yourself by wearing rubber gloves when you clean. An enzyme cleaner like Biokleen Bac-Out is good for messes on the carpet, and an antibacterial cleaner or bleach for hard surfaces is highly effective. Diatomaceous earth can help ensure eggs buried in carpets and other soft surfaces have been taken care of. Learn more about how to clean your home after finding out your cat has worms in our in-depth guide.

How To Prevent Worm Infections in Cats

No one wants to deal with this twice. The good news is that worm infestations are preventable with a few proactive steps.

Monthly Flea and Worm Prevention

Use a vet-recommended flea control product year-round. Some monthly treatments also include dewormers, which can protect against a range of parasites. Outdoor cats, or those in multi-cat households, may need more frequent monitoring.

Safe Indoor Habits

The safest cat is an indoor cat. Keeping your cat inside drastically reduces the risk of ingesting prey, fleas, or contaminated soil. If outdoor access is non-negotiable, consider a secure “catio,” a stroller, or leash-walks to limit exposure.

Regular Veterinary Care

Annual vet checkups should include a fecal exam to screen for parasites, even if your cat seems healthy. Catching worms early prevents complications and lowers the risk of spread to other pets or to humans.

Can Humans Get Worms from Cats?

Unfortunately, yes, some worms that infect cats can also infect humans. These are called zoonotic parasites, and while the risk is relatively low with proper hygiene, it’s something all cat owners should take seriously.

Understanding Zoonotic Risk

The most common zoonotic worms in cats are roundworms and hookworms.

• Roundworms can cause a condition in humans called visceral larva migrans, where larvae migrate through organs and tissues. In rare cases, they may even affect the eyes (ocular larva migrans), leading to vision problems.
• Hookworms can cause cutaneous larva migrans, a skin infection where larvae burrow just under the skin, leading to itching, rashes, and discomfort.

Humans typically become infected by accidentally ingesting microscopic parasite eggs. This can happen through:

• Handling contaminated litter or soil
• Touching infected surfaces and then touching your mouth or food
• Letting cats lick your face or hands after grooming themselves

Children, pregnant people, and immunocompromised individuals are more vulnerable to complications from zoonotic parasites.

Other pets can pick up an infection by accidentally ingesting their microscopic eggs. It is also possible for humans to become infected with Toxocara, usually from unwashed hands. Most people don’t get sick and are asymptomatic, but occasionally it can cause problems. Toxocara could cause blindness and problems with abdominal issues (visceral toxocariasis).

– Dr Rebecca MacMillan, BVetMed BSAVA PGCertSAM MRCVS

Hygiene Tips for Families and Kids

Reducing the risk of transmission is simple but requires consistency. Here are the best practices:

• Wash your hands thoroughly after cleaning the litter box, handling the cat, or gardening
• Wear gloves when scooping litter or working in soil, especially if cats use the garden as a toilet
• Keep litter boxes away from kitchens and food prep areas
• Discourage children from playing in areas where cats may defecate
• Clean food bowls, bedding, and shared surfaces regularly
• Avoid letting cats lick your face, especially around the mouth or eyes

Most importantly, keep your cat on a regular deworming and flea prevention schedule. A healthy, parasite-free cat is the best line of defense.

Quick Answers for Panicked Cat Owners

Sometimes, you just need fast facts without the fluff. Here are quick answers to common questions cat owners ask when a worm makes an unwanted appearance. If you don’t see yours, let us know in the comments.

Can Indoor Cats Get Worms?

Yes. While outdoor cats are more at risk, indoor cats can still become infected. Fleas can hitch a ride inside on your clothes or other pets, and indoor bugs or rodents can also carry parasite eggs. No cat is entirely immune without preventive care.

Should I Isolate My Cat?

In some cases, yes. While worms aren’t spread through the air, many intestinal parasites are contagious through fecal-oral transmission, meaning other pets (or even people) can become infected if they come into contact with contaminated litter, bedding, or grooming areas.

You should isolate your cat if:

• You have multiple cats or pets sharing litter boxes, food bowls, or bedding
• Your infected cat is showing severe symptoms or has diarrhea
• There are young kittens, elderly pets, or immunocompromised animals in the home
• Your veterinarian specifically recommends isolation based on the worm type

What isolation looks like:

• Confine your cat to one room (like a bathroom or spare bedroom)
• Use a separate litter box and food/water bowls
• Wear gloves when cleaning up after them
• Wash your hands thoroughly after any contact
• Limit interactions with children during the treatment period

Most cats can be reintegrated into the household after 48–72 hours of starting treatment, but your vet may recommend a longer isolation window depending on the parasite and treatment response.

Is One Treatment Enough?

Sometimes, but not always. Many dewormers require follow-up doses to break the parasite’s lifecycle and eliminate eggs or larvae that survived the first round. Always follow your veterinarian’s full treatment plan, even if your cat seems better after the first dose.

What Do Roundworms Look Like in Vomit?

They’re long, white or off-white, and resemble cooked spaghetti. You may see them moving if freshly expelled. It’s unpleasant, but identifying the worm’s appearance can help your vet choose the right medication.

Take Action, But Don’t Panic

Seeing a worm in your cat’s vomit is shocking, but it’s also a clear signal that your cat needs help. The good news? You caught it.

To recap:

• Worms in vomit mean a parasite problem that needs treatment
• It’s common, manageable, and treatable with proper care
• Your vet is your best resource. Act quickly
• Good hygiene and regular prevention can stop this from happening again

You’re not a bad pet parent. You’re a proactive one. Take a deep breath, make the call to your vet, and start the path to getting your cat healthy and worm-free.

Still Seeing Vomiting? Worms Aren’t the Only Cause

Cats vomit for a variety of reasons, and while worms are one possibility, they’re far from the only cause. Hairballs are among the most common, especially in long-haired cats or those that groom frequently. Occasional hairball vomiting is usually normal, but frequent or difficult episodes may signal over-grooming, stress, or poor digestion. In some cases, switching to a hairball control cat food can help reduce frequency and improve coat health.

Other causes of vomiting include eating too quickly, food sensitivities, or more serious health concerns. If your cat is vomiting after every meal, throwing up undigested food, or gagging without vomiting, there may be an underlying issue worth exploring. Keep an eye out for unusual symptoms like foaming at the mouth, changes in appetite, or sudden behavioral shifts. Tracking patterns and acting early can make a big difference in keeping your cat healthy and comfortable.

Have You Dealt With This?

Has your cat ever thrown up a worm or shown other strange symptoms that caught you off guard? Share your experience in the comments below. Your story might help another cat parent feel a little less panicked, and a lot more prepared.