Cat Diarrhea with Worms: Causes and Treatment Options

By Dr. Zubair Khalid, DVM, MS, PhD · 2026-08-14

Key Takeaways

• Visible worms in cat stool, commonly roundworms (spaghetti-like) or tapeworms (rice-grain segments), indicate intestinal parasitism causing diarrhea due to intestinal lining damage and inflammation.
• Urgent veterinary care is critical for kittens (<6 months), elderly cats, or immunocompromised individuals exhibiting signs like pale gums, weakness, collapse, or repeated vomiting, as dehydration and blood loss can be rapid and life-threatening.
• Diagnosis relies on a veterinary fecal floatation test to identify parasite eggs, as not all worms (e.g., hookworms) or other microscopic causes of diarrhea (e.g., coccidia, giardia) are visible to the naked eye.
• Treatment involves prescription deworming medication specific to the identified parasite and cat's weight, often requiring a second dose 2-4 weeks later to target newly hatched worms, alongside supportive care like bland diets or fluids if needed.
• Prevention strategies include year-round broad-spectrum parasite prevention, strict flea control (essential for tapeworm prevention), daily litter box cleaning, and regular veterinary fecal examinations at least annually.
• Owners should never administer human anti-diarrhea medications or over-the-counter dewormers without veterinary guidance, as incorrect drugs or dosages can be ineffective or toxic, and delaying proper diagnosis can mask other serious underlying conditions.

Finding worms in your cat's stool is alarming, but you are not alone and this is a common problem. The most important thing to know right now is that most cases of diarrhea with worms are treatable, and your cat will likely recover fully with the right veterinary care. However, some situations are true emergencies. If your cat is very young, very old, or has a weakened immune system, worms and diarrhea can cause dangerous dehydration or blood loss quickly.

Call your veterinarian today. Do not wait to see if it improves on its own. While you arrange that appointment, read on to understand what you are seeing, what might be causing it, and what treatment will involve.

Is This an Emergency?

Use this table to decide how quickly your cat needs care. If you are unsure which column fits, choose the faster option. When in doubt, call your vet or an emergency clinic.

{
 "type": "triage",
 "title": "Urgency triage by severity of signs",
 "tiers": [
  {
   "tier": "danger",
   "label": "Go to an emergency vet now",
   "signs": [
    "Pale or white gums, weakness or collapse, difficulty breathing, a swollen or painful belly, vomiting repeatedly, or you see a large mass of worms tangled together in the stool or vomit",
    "Also go now if your cat is a kitten under 6 months old with any of these signs, or if your cat cannot stand"
   ],
   "action": [
    "Do not wait for a regular appointment",
    "Transport your cat carefully and go immediately"
   ]
  },
  {
   "tier": "warn",
   "label": "Book a same-day appointment",
   "signs": [
    "Diarrhea that is watery, frequent (more than 3 times in a few hours), or contains blood",
    "Your cat is still eating and drinking but seems tired or less playful",
    "You see worms in the stool that look like rice grains or spaghetti",
    "Your cat has had diarrhea for more than 24 hours"
   ],
   "action": [
    "Call your regular clinic as soon as they open",
    "Ask for the earliest slot today"
   ]
  },
  {
   "tier": "safe",
   "label": "Watch at home for up to 24 hours",
   "signs": [
    "A single soft stool with a worm visible, no other signs of illness, your cat is eating, drinking, playing, and acting normally",
    "You have already spoken to your vet and they have advised home monitoring"
   ],
   "action": [
    "Keep your cat indoors, offer fresh water, and monitor closely",
    "If diarrhea returns or any new sign appears, move up to the same-day category"
   ]
  }
 ]
}

What Are These Worms?

The worms you see in your cat's poop are adult intestinal parasites. The two most common types visible to the naked eye are roundworms and tapeworms.

Roundworms look like cooked spaghetti, pale cream or white, and can be several inches long. They often come out coiled or moving in the stool. Tapeworms look different. They shed segments that resemble grains of white rice, and these segments may wriggle briefly after your cat poops. You might also see them stuck to the fur around your cat's rear end.

Not all worms are visible. Hookworms are tiny and rarely seen without a microscope, but they can cause severe diarrhea and anemia, which is a low number of red blood cells. Coccidia and giardia are microscopic parasites that cause diarrhea but are not worms at all. Your vet can identify the exact culprit with a stool sample test called a fecal float.

Why Does Diarrhea Happen With Worms?

Worms damage the lining of your cat's intestines. This damage causes inflammation, which is the body's response to irritation, and it interferes with normal water absorption. The result is loose, frequent stools. Some worms also feed on blood, which can lead to anemia and make diarrhea worse.

Kittens are especially vulnerable. They can be born with worms passed from their mother, and a heavy worm burden can block their tiny intestines entirely. If you have a kitten with diarrhea and worms, treat this as more urgent than the same situation in an adult cat.

What Else Could Be Causing the Diarrhea?

Worms are a likely cause, but they are not the only possibility. Diarrhea has many triggers, and sometimes worms are found alongside another problem. Your vet will consider these other causes:

• Dietary indiscretion: Your cat ate something unusual, spoiled food, or a new treat that upset the stomach.
• Infections: Bacterial or viral infections can cause diarrhea, especially in multi-cat households or shelters.
• Inflammatory bowel disease: A chronic condition where the intestines are persistently inflamed, unrelated to parasites.
• Other parasites: As mentioned, coccidia and giardia are common and require different medications than worms.
• Toxins or foreign objects: Something your cat swallowed could irritate the gut.

This is why a stool sample and a physical exam matter. Treating for worms when the real cause is a bacterial infection will not fix the diarrhea. Your vet needs to confirm the diagnosis before starting treatment.

How Will My Vet Treat This?

Treatment starts with a proper diagnosis. Bring a fresh stool sample, ideally collected within the last 12 hours and kept in a clean container or baggie. Your vet will examine it and may run tests to identify the parasite.

The treatment is a deworming medication. These drugs are safe and effective, but they are prescription medicines for a reason. The correct drug depends on the type of worm, and the dose depends on your cat's weight. Never give a human deworming product or an over-the-counter pet product without your vet's approval. Giving the wrong drug or the wrong dose can be ineffective or harmful, especially in kittens.

Your vet will tell you the exact dose and schedule. Many dewormers require a second dose two to four weeks later to catch newly hatched worms. You must complete the full course, even if the diarrhea stops sooner.

Alongside deworming, your vet may recommend supportive care for the diarrhea. This can include a bland diet, probiotics, or fluids if your cat is dehydrated. These measures support recovery but do not replace the dewormer.

When to Call Back

After treatment, your cat should improve within a few days. Call your vet if the diarrhea continues beyond 48 hours after the first deworming dose, if blood appears in the stool, if your cat stops eating, or if you see more worms passed. Persistent diarrhea can signal a different underlying issue that needs further testing.

Also, protect yourself and other pets. Some worms, especially roundworms, can spread to humans, particularly children. Wash your hands thoroughly after handling your cat's litter box, and clean the litter box daily. Your vet can advise on whether other pets in the home need treatment too.

For more background on digestive problems in cats, the MSD Veterinary Manual offers owner-friendly explanations of causes and warning signs. The American Veterinary Medical Association also provides guidance on recognizing emergencies and working with your veterinarian. Your vet remains the best source of advice for your specific cat.

What You Can Do at Home Right Now

If your cat has diarrhea and you can see worms, your first step is to call your veterinarian. Do not wait to see if it improves on its own. Intestinal parasites cause dehydration and weight loss, and kittens can decline quickly.

While you wait for advice or an appointment, you can do several safe things.

Offer fresh water at all times. Diarrhea removes fluid from the body, so your cat needs easy access to clean water. You can add a second water bowl in a different room. Some cats prefer running water, so a pet fountain may encourage drinking.

Feed a bland, easily digested meal if your cat is eating normally. Plain boiled chicken breast without skin or bone, or plain white rice, can be offered in small amounts. Do not add salt, oil, or seasonings. Keep this diet for no more than two days unless your vet says otherwise. A sudden diet change can make diarrhea worse, so introduce the bland food gradually over a day.

Do not give any over-the-counter anti-diarrhea medicine made for people. Many human medications are toxic to cats. Do not give deworming medicine you have at home from a previous pet or a different animal. The wrong drug or the wrong dose can harm your cat, and the wrong drug will not kill the specific worm your cat has.

Do not let your cat outside until the worms are treated. This prevents your cat from picking up more parasites and stops eggs from contaminating your yard.

Wash your hands thoroughly after handling your cat, its litter box, or its stool. Some cat worms can infect people, especially children and pregnant women. Wear gloves when cleaning the litter box and dispose of stool in a sealed bag.

What to Measure and Write Down Before You Call

Your veterinarian will ask specific questions. Having answers ready saves time and helps them judge urgency.

Write down how many times your cat has had diarrhea in the past 24 hours. Note whether it is watery, soft, or mixed with mucus. Describe the worms exactly. Are they long and thin like spaghetti, or short and flat like grains of rice? Did you see them in the stool, near the anus, or in vomit?

Weigh your cat if you can. A kitchen scale works for small cats. For larger cats, hold them on a bathroom scale and subtract your own weight. A rapid weight drop is a serious sign.

Check your cat's gum color. Lift the lip and look. Healthy gums are pink, like your own. Pale, white, or gray gums can mean blood loss from a heavy worm burden. That is an emergency.

Count your cat's breathing rate at rest. Watch the chest rise and fall for 15 seconds and multiply by four. Normal is roughly 20 to 30 breaths per minute. Faster breathing, especially with pale gums, needs immediate care.

Note whether your cat is still drinking, eating, and using the litter box normally. Track energy level. A cat that is hiding, weak, or unwilling to move is more concerning than one that is active between bouts of diarrhea.

The Veterinary Visit: What to Expect

Your vet will start with a physical examination. They will feel your cat's abdomen to check for pain, masses, or thickened bowel. They will listen to the heart and lungs and check hydration by lifting the skin at the back of the neck. They may take your cat's temperature.

The vet will ask about your cat's history. Be ready to describe when the diarrhea started, what your cat eats, whether it hunts or goes outdoors, and whether you have other pets.

A fecal test is the standard way to identify worms. The vet examines a small stool sample under a microscope to look for eggs. Sometimes more than one sample is needed because worms shed eggs intermittently. In some cases, the vet may recommend a blood test to check for heartworm or other parasites.

The cost of a visit varies widely by region and clinic. A basic office visit with a fecal test might range from roughly $75 to $200. Bloodwork, fluids, or hospitalization add to that. These are general ranges only, not quotes. Ask your clinic for an estimate before treatment begins.

Common Cat Worms at a Glance

A Deworming Protocol Checklist

A proper deworming plan is more than one dose. Use this checklist when discussing treatment with your vet.

• Confirm the worm type with a fecal test before treating.
• Get a prescription product made for cats, never a dog product.
• Ask for the exact dose based on your cat's current weight.
• Give the full course, even if diarrhea improves.
• Mark the calendar for the repeat dose your vet recommends.
• Treat all pets in the household if your vet advises it.
• Control fleas, since tapeworms come from fleas.
• Clean the litter box daily and wash it with hot water.
• Keep your cat indoors during treatment.
• Schedule a follow-up fecal test to confirm the worms are gone.

When an Online Vet Can Help, and When It Cannot

Some situations in this article require hands-on care and must not be handled remotely. Pale gums, rapid breathing, weakness, collapse, or a cat that refuses to drink all need in-person emergency care immediately. A suspected blockage, severe dehydration, or a very young kitten with diarrhea also needs a physical exam. No video call can measure gum color accurately or feel a swollen abdomen.

A remote consultation is genuinely useful for early or mild cases. If your cat has had one or two soft stools, you can see worms, and your cat is eating, drinking, and acting normal, an online vet can help you decide whether a visit is needed today or can wait until tomorrow. They can also answer questions about medication side effects, help you interpret a fecal test result, or guide a follow-up for a chronic condition.

A remote vet can take a detailed history, look at visible signs on video, and advise on next steps. In many states they can prescribe medication. But they cannot palpate the abdomen, listen to the chest, take a temperature, run bloodwork, or image anything. Prescribing rules differ by state, and a veterinarian may require an in-person examination before prescribing deworming medication. Use remote care as a triage tool, not a replacement for the exam your cat may need.

Common Mistakes Owners Make With Worms and Diarrhea

Seeing worms in your cat's stool is alarming, and it is easy to react quickly in the wrong way. Here are the most frequent errors and the safer approach.

The most serious mistake is guessing. A cat with diarrhea and worms may also have another problem, such as a bacterial infection, a parasite like giardia, or an inflammatory bowel condition. The MSD Veterinary Manual for pet owners explains that diarrhea has many causes, and treating only the visible worms can delay care for the real issue.

Another common error is using a dewormer meant for a different species or weight. Dosing must come from your treating veterinarian. Cats metabolize drugs differently than dogs, and a dose that is too low will not kill the worms, while a dose that is too high can harm your cat.

How to Reduce the Chance of It Happening Again

Prevention focuses on three areas: your cat, your home, and your routine.

Keep your cat on a year-round parasite prevention plan. Many monthly products protect against worms and fleas, and fleas can carry tapeworms. Ask your vet which product fits your cat's lifestyle. Indoor cats still need protection, because insects and rodents can enter the home.

Clean the litter box daily. Worm eggs need time to become infectious, so removing feces quickly breaks the cycle. Wear gloves and wash your hands afterward. For outdoor areas, remove feces promptly and consider limiting your cat's hunting behavior.

Schedule a fecal check at least once a year, or twice a year for cats who go outside. The American Veterinary Medical Association recommends regular veterinary visits as the foundation of preventive care. A stool sample can catch worms before you see them in diarrhea.

Control fleas strictly. Tapeworms come from ingesting fleas, so flea prevention is tapeworm prevention. Treat all pets in the home, also the cat with symptoms.

What Recovery and Ongoing Management Usually Look Like

Most cats improve quickly once they receive the correct dewormer. Diarrhea often begins to firm up within 24 to 72 hours. Full recovery of the intestinal lining can take one to two weeks, so some soft stool may continue even after the worms are gone.

Your vet will likely schedule a follow-up fecal test two to four weeks after treatment. This confirms the worms are gone and checks for reinfection. Some protocols require a second deworming dose at this point, because the first dose may not kill immature worms.

During recovery, feed a bland, easily digestible diet if your vet recommends it. This might be a prescription gastrointestinal food or a simple home-cooked option your vet approves. Do not switch foods abruptly. Introduce any new food gradually over three to five days.

Watch for these signs during recovery:

• Diarrhea that worsens or lasts more than five days after treatment
• Vomiting that prevents drinking water
• Lethargy that does not improve within 48 hours
• Blood in the stool that increases
• A swollen or painful belly

If any of these appear, call your vet the same day. Persistent diarrhea can cause dehydration, especially in kittens and older cats.

Kittens may need extra care. They dehydrate faster than adult cats, and a heavy worm burden can slow their growth. Follow your vet's deworming schedule for kittens closely, usually starting at two to three weeks of age and repeating every two weeks until weaned.

Ongoing management means staying consistent. Mark deworming dates on your calendar. Keep stool samples ready for checkups. Maintain flea control year-round. These habits reduce the chance of a repeat episode.

Frequently Asked Questions

Can I catch worms from my cat?

Yes, some cat worms can pass to people. Roundworms and hookworms are the main concerns. Children are at higher risk because they may touch contaminated soil or litter and then put hands in their mouths. Wear gloves when cleaning the litter box, wash hands thoroughly, and keep children away from areas where your cat defecates. If you develop skin irritation, stomach pain, or unusual symptoms, see your doctor and mention your cat had worms. Your vet can explain which specific worm your cat has and whether it poses a risk to your family.

How long does it take for the dewormer to work?

Most dewormers begin killing worms within hours of being given. You may see dead worms in your cat's stool within 24 to 48 hours. The diarrhea often improves in the same period, but it can take up to a week for the gut to heal fully. A single dose rarely cures the infection completely. Your vet will tell you when to give the second dose, usually two to four weeks later, and will confirm with a follow-up stool test.

My cat is acting normal but has worms in diarrhea. Is that possible?

Yes. Some cats carry a significant worm burden while still eating, playing, and behaving normally. The worms steal nutrients, but the cat may compensate for a while. This is why routine fecal checks matter. However, normal behavior does not mean you can wait indefinitely. Worms can cause anemia, weight loss, and intestinal blockages over time. If you see worms, schedule a vet visit within a day or two, even if your cat seems fine.

Can I use the same dewormer for all my cats?

Not without checking with your vet. Cats of different weights need different doses, and some dewormers are not safe for kittens under a certain age. Also, not all cats in the home may have the same type of worm. Your vet can test each cat or advise a safe protocol for the whole household. Treating every cat at the same time is often wise, but the product and dose must be appropriate for each individual.

What if the diarrhea comes back after treatment?

A return of diarrhea can mean the worms were not fully cleared, your cat was reinfected, or the original problem was something else. Do not repeat the same dewormer on your own. Collect a fresh stool sample and take your cat to the vet. The vet may run additional tests for other parasites, bacteria, or digestive conditions. Recurrent diarrhea needs a diagnosis, not another guess.

Should I change my cat's food permanently after worms?

Not necessarily. Once the worms are gone and the diarrhea resolves, many cats return to their normal diet. If your cat has ongoing digestive sensitivity, your vet may recommend a longer course of a gastrointestinal diet or a food trial. Some cats develop temporary lactose intolerance or trouble digesting certain proteins after a heavy worm infection. Follow your vet's feeding advice and transition back to regular food slowly over several days.

Related Clinical & Scientific Guides

• Cat Straining to Poop but Only Passing Mucus: Causes and Care
• Cat Upset Stomach: Home Remedies That Are Safe
• Cat Straining to Poop but Nothing Comes Out: Emergency or Not?

References and Further Reading

• MSD Veterinary Manual Digestive Disorders of Dogs and Cats
• AVMA Pet Owner Resources
• MSD Veterinary Manual Pet Owner Version
• AAHA Pet Owner Resources

Related Articles

• Cat Diarrhea with Mucus: Causes and When to Worry
• Cat Constipation After Diarrhea: Causes and Relief
• Cat Diarrhea After Eating: Causes and When to Act
• Cat Diarrhea with Blood and Mucus: Causes and When to Act Fast
• Cat Vomiting and Diarrhea: When to Worry

This article is general educational information for pet owners. It is not a substitute for veterinary diagnosis, examination, or treatment. If your pet is showing severe or rapidly worsening signs, contact an emergency veterinary hospital immediately.