Coccidia in Cats: What It Is and How to Treat It

If your cat has been having watery or bloody diarrhea, especially right after adoption, coccidia might be why. It sounds alarming, but here’s the reassuring part: coccidia is common, well-understood, and treatable.

Here’s what coccidia actually is, how your cat got it, and what to do next.

What is coccidia in cats?

Coccidia (the infection is called coccidiosis) is caused by a tiny, microscopic parasite that lives in the lining of your cat’s intestines. The most common type in cats is called Cystoisospora, a single-celled organism that spreads through contaminated feces and can cause real problems, especially for kittens.

Most healthy adult cats can carry low levels of coccidia without showing any symptoms at all. The trouble starts when a cat’s immune system is compromised, whether from stress, illness, or age, and the parasite gets the upper hand.

Symptoms of coccidia in cats

The most obvious sign is loose, watery, or bloody stool. You might notice your cat straining in the litter box, making more trips than usual, or producing poop that looks pale, liquid, or flecked with blood or mucus. That’s the intestinal lining responding to the parasite’s damage.

Other signs of coccidia in cats include:

• Loss of appetite
• Vomiting
• Lethargy or low energy
• Weight loss
• Dehydration (sunken eyes, dry gums, skin that doesn’t spring back when gently pinched)
• Hunched posture or visible discomfort

Some adult cats carry coccidia without showing any symptoms at all. But in kittens or cats that are already sick or stressed, the infection can hit hard and fast. Dehydration is the biggest immediate danger, especially in very young kittens.

How coccidia spreads in cats

Coccidia spreads through what vets call the fecal-oral route. That means a cat ingests the parasite by coming into contact with infected feces, whether by grooming their paws after stepping in a contaminated area, sharing a litter box with an infected cat, or drinking water near contaminated soil.

The parasite exits the body as oocysts (tiny egg-like structures in the poop) that can survive in the environment for weeks, especially in warm, moist conditions. This is why environmental contamination is such a big part of the problem. Even after a cat recovers, their surroundings can reinfect them if not cleaned properly.

Why kittens and multi-cat homes are hardest hit, and can you catch it?

• Kittens are especially vulnerable; their immune systems aren’t fully developed yet, so a parasite load that a healthy adult cat could manage without symptoms can overwhelm a kitten quickly, leading to severe diarrhea, dehydration, and rapid weight loss. This is why coccidiosis is so common in kittens from shelters, rescues, and catteries, where many cats share litter boxes and close quarters.
• Stress plays a real role; when a cat is stressed, including from a new home, a vet visit, or unfamiliar animals, their immune response dips and a low-level infection that was previously controlled can suddenly flare. It’s one reason newly adopted cats often show symptoms within days of coming home, even when they seemed healthy at the shelter.
• Multi-cat homes carry higher risk; shared litter boxes become transmission points, and oocysts in coccidia-positive stool can contaminate surfaces throughout the home. Any new cat should be isolated and tested before being introduced to resident pets.

Can coccidia transfer from cats to humans?

This is one of the most common questions pet owners search for, and the short answer is: very unlikely. The Cystoisospora species that infects cats is largely species-specific, meaning it’s adapted to cats and doesn’t readily infect humans. It’s a different species from the coccidia that can affect people.

That said, basic hygiene still matters: wash your hands after cleaning litter boxes, and keep litter areas clean, especially if anyone in your household is immunocompromised. But you don’t need to panic about catching coccidiosis from your cat.

Diagnosing coccidia in cats

Your vet will diagnose coccidia with a fecal test, technically called a fecal flotation. You bring in a small sample of your cat’s poop, the vet mixes it with a special solution that causes parasite eggs to float to the surface, and then examines it under a microscope. It’s straightforward and usually gives results the same day.

Your vet may also run a broader fecal panel to rule out other parasites or bacterial infections that can look similar, like giardia or salmonella. If your cat is severely ill, bloodwork may be added to check hydration levels and organ function.

Diagnosis and treatment

How vets diagnose coccidia

Your vet will diagnose coccidia with a fecal flotation test. You bring in a small sample of your cat’s stool, the vet mixes it with a solution that causes parasite eggs to float to the surface, and examines it under a microscope. It’s straightforward and usually gives results the same day.

Your vet may also run a broader fecal panel to rule out other parasites or infections that can look similar, like giardia or salmonella. If your cat is severely ill, bloodwork may be added to check hydration levels and organ function.

How to treat coccidia in cats

The most commonly prescribed treatment is sulfadimethoxine, sold under the brand name Albon. It’s an antiparasitic medication given orally, typically once daily for 5 to 20 days depending on the severity of the infection. It works by blocking the parasite’s ability to reproduce, giving your cat’s immune system time to clear the infection.

Alongside medication, supportive care is a key part of treatment, especially for kittens:

• Fluid therapy; either at the clinic or subcutaneous fluids at home if your cat is dehydrated
• A bland diet; to reduce intestinal irritation while the gut heals
• Probiotics; to help restore healthy gut bacteria after the infection
• A follow-up fecal test; after treatment to confirm the infection has fully cleared

There’s no safe or reliable way to treat coccidia at home without a vet. Over-the-counter dewormers don’t work against coccidia, and waiting it out while your cat, especially a kitten, loses fluids is genuinely risky. Get a fecal test, get the right medication, and follow through with the full course.

Preventing reinfection

Keeping litter boxes clean (scooping daily and disinfecting with diluted bleach or an ammonia-based cleaner), washing hands after handling feces, and isolating new cats before introducing them to resident pets all reduce the risk of environmental contamination and spread.

Does pet insurance cover coccidia in cats?

Vet visits, fecal tests, Albon prescriptions, and fluid therapy can add up quickly, especially if your cat needs follow-up appointments. Lemonade’s base illness coverage can help with those costs, including diagnostics, prescribed medications, and related vet visits, as long as the infection isn’t pre-existing and develops after the illness waiting period has passed (which varies by state).

If your cat already has coccidia when you enroll, that infection won’t be covered. Enrolling before your cat gets sick is what makes the coverage work when you need it most.

Before we go

Finding out your cat has coccidia is stressful, especially if they’re a young kitten or you’ve just brought them home. But this is one of those conditions where early action makes a real difference. A fecal test, the right medication, and a clean environment are usually all it takes to get your cat back on track. If you’re seeing watery or bloody diarrhea, don’t wait to call your vet.

Frequently Asked Questions

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