Hidden Dangers: Can Cat Litter Make You Sick?


Health problems linked to cat litter:

  • Lung disease
  • Bentonite toxicosis
  • Mental illness
  • Hyperthyroidism

The internet is littered (pardon the pun) with a lot of info about cat litter and health. It’s enough to make anyone confused.

In this article I’ll go through the research linking cat litter with health problems and what to do to keep yourself safe.

I recommend seeking the advice of a vet for any further questions. The advice in this article is not intended as medical advice.

Can Cat Litter Make You Sick?


Cat litter is linked to:

  • Lung disease
  • Mental illness
  • Bentonite toxicosis
  • Hyperthyroidism
  • Pulmonary fibrosis

Here’s what the science has to say.

Lung Disease

Linked to bentonite clay cat litter.

Bentonite clay litter contains crystalline silica.

Crystalline silica is a mineral found in natural Earth materials like rock, concrete, and other industrial materials as well as clay cat litter.

It’s cheap and offers great water absorption for cat litter.

The particles can enter the airways without any immediate effect to health. It’s odorless, colorless, and non-irritating.

However it can affect human health from inhalation of silica dust.


In 2022, a 44 year old woman with kidney failure checked into hospital with:

  • Weight loss
  • Coughing
  • Fever
  • Decreased exercise tolerance.

A biopsy found lesions in the lungs with silicon deposits.

History revealed she owned 9 cats all using bentonite clay litter.

Her lung and kidney function improved in 4 months with prednisone and removal of all bentonite clay cat litter.

A similar case study in 2012 saw a 44 year old woman with 8 cats presented with breathing problems.

The issue also resolved by avoiding bentonite clay cat litter.

Recently, there’s been a rise in silicosis (lung disease) from tradesman using stone products in Australia. Some workers have irreversible lung damage.

Bottom Line:

Both case studies are of people with a lot of cats.

More cats = more litter = more dust.

There’s also evidence from tradesman with heavy exposure to silicon dust from work.

For single cat owners, harm is less likely. I feel it’s best avoided.

Bentonite clay
Bentonite clay contains silica dust, which affects lung function if inhaled

Bentonite Toxicosis

Bentonite clay litter can affect cats too if they eat it.

A 1996 study reported a 2 year old cat visiting a clinic with:

  • Lethargy
  • Muscle weakness
  • Dehydration

The cat also had a potassium deficiency (hypokalemia).

Researchers found the cat ingested bentonite clay litter. The cats health improved when taken off clay litter.

However the owner put their cat back on the litter, the cats health declined, and the owner got the cat euthanized.

Bottom Line:

Doesn’t seem like there’s much research on this one.

If your cat tries to eat litter, then I think it’s best to opt for a plant based litter for safety.

A cat looking at cat litter
Eating clay cat litter can make your cat sick

Mental Illness

Cat poo can have parasites.

One is a brain parasite called toxoplasma gondii, which affects 40% of cats.

A study of 40,000 Danish blood donors found those exposed to cat feces had a 47% increased risk of schizophrenia (translates to about a 1% higher rate).

The parasite is also transmitted in raw meat.

Globally, the parasite infects about 1 billion people.

A study in Iraq found 27.5% of women visiting a vet clinic infected with the parasite (toxoplasmosis). About 10% of cats had feces infected with the parasite.

A Maryland lab studied this brain parasite, but got shut down.

The lab gave cats infected meat to harvest parasites, then euthanized them. This drew an uproar in animal activists, hence the decision to stop research.

So without more research, it’s unclear what the full effect to health is.

Bottom Line:

Stay clean.

Avoid touching cat poo directly and maintain daily cleaning.

This reduces your risk of infection.

About 10% of cats feces contain a brain parasite that infects humans


Affects 10% of geriatric cats.

The rate of hyperthyroidism is increasing in cats.

1 in 10 cats were hyperthyroid in 2019 compared to 1 in 100 in 1980.

This is an overproduction of thyroid hormone with symptoms including:

  • Weight loss
  • Diarrhea
  • Vomiting
  • Increased appetite

Cat litter may have a role in the disease.

A 1999 analysis of over 300 hyperthyroid cats found a 3 fold increase in the disease if using cat litter.

What type of litter is unclear.

There’s many possible causes of hyperthyroidism:

  • Flame retardant in furniture
  • High iodine foods (e.g. fish)
  • Flea sprays
  • Flea powders
  • Indoor dwelling
  • Canned cat food

Flame retardant mimics thyroid hormone in cats. The rise in hyperthyroidism in cats follows the increase in the use of flame retardant.

Bottom Line:

Cat litter is possibly linked to hyperthyroidism, but flame retardant is most likely to blame.

If your cat is hyperthyroid it couldn’t hurt to switch cat litter to see if it helps with management. More research needed though.

Flame retardant
Flame retardant may increase the risk of hyperthyroidism in cats


Health problems linked to cat litter include:

  • Lung disease
  • Bentonite toxicosis
  • Mental illness
  • Hyperthyroidism

Exposure to heavy amounts of dust from bentonite clay litter increases the risk of health problems in the lungs.

Most cases are from tradesman or those with a lot of cats in the house.

Cat poo may contain a parasite linked with mental illness in humans. Finally, cat litter is also linked to hyperthyroidism.

Consider using plant based litter to reduce the risk of illness. Maintain daily litter cleaning habits.

>> Recommended plant based cat litter World’s Best Cat Litter

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