Emergency contacts — save these now:
- ASPCA Animal Poison Control Center: 888-426-4435 (24 hours a day, 7 days a week; per-incident fee may apply)
- Pet Poison Helpline: 855-764-7661 (24/7; fee may apply)
- Your local emergency veterinary hospital
Do not wait for symptoms before calling. Many cat toxins — particularly lilies and acetaminophen — cause irreversible organ damage within hours, well before visible clinical signs appear.
Why Cats Face Unique Toxic Risks
Cats are not simply small dogs. Their metabolism differs from dogs and humans in ways that make them uniquely vulnerable to a set of substances that other species can tolerate. Three metabolic differences are especially important:
Glucuronidation deficiency: Cats have severely limited activity of glucuronyl transferase enzymes, which are responsible for metabolizing and eliminating many phenolic compounds, medications, and toxins. Substances that dogs and humans metabolize safely — aspirin, acetaminophen, many essential oils — accumulate to toxic levels in cats because of this enzymatic deficiency.
Obligate carnivore metabolism: Cats have evolved to process animal protein and fat. Their liver and gastrointestinal systems are not equipped to handle many plant compounds, plant toxins, or the antioxidant phenolics found in plant foods at concentrations that other animals tolerate without issue.
Small body mass: The average domestic cat weighs 3.6-5 kg (8-11 lbs). This means that even very small doses of a toxic substance represent a significant concentration per kilogram of body weight.
Critical Category: Life-Threatening at Small Doses
True Lilies: The Most Dangerous Common Household Plant
"Easter lilies (Lilium longiflorum), tiger lilies, Asiatic lilies, stargazer lilies, Japanese show lilies, and day lilies (Hemerocallis species) are acutely nephrotoxic to cats. The toxic compound remains unidentified, but ingestion of even small amounts causes acute renal tubular necrosis. All parts of the plant are toxic, including leaves, petals, pollen, stems, and the water in a vase." — ASPCA Animal Poison Control Center
This is the most important warning in this entire article. True lilies (Lilium and Hemerocallis genera) kill cats. The dose needed for fatal toxicity is extraordinarily small. Documented cases of kidney failure have occurred from:
- A cat chewing one or two petals
- A cat licking lily pollen off its fur after rubbing against a flower arrangement
- A cat drinking from a vase that contained lily stems
Symptoms: Vomiting within 2 hours, followed by apparent improvement, followed by rapid development of acute kidney failure within 24-72 hours
Outcome without treatment: Irreversible kidney failure and death within 3-6 days
Treatment: Aggressive IV fluid diuresis initiated within the first few hours post-exposure gives the best chance of preventing permanent kidney damage. Treatment initiated after kidney failure is established has a poor prognosis.
Action: If your cat has had ANY contact with a true lily — chewed a leaf, licked pollen, or drank from the vase — call ASPCA APCC (888-426-4435) or an emergency vet immediately. Do not wait for symptoms.
Plants commonly confused with true lilies that are NOT nephrotoxic to cats (but are toxic through different mechanisms):
- Lily of the valley (Convallaria majalis): toxic via cardiac glycosides — causes heart arrhythmias; still dangerous
- Peace lily (Spathiphyllum): causes oral irritation, drooling, GI upset — not kidney failure
Xylitol
While xylitol causes rapid and severe hypoglycemia in dogs, cats appear less acutely sensitive to its insulin-releasing effect. However, the ASPCA Animal Poison Control Center advises treating xylitol ingestion in cats as a potential toxicologic emergency. Xylitol is widely found in sugar-free gum, certain peanut butter brands, vitamins, dental products, and sugar-free baked goods.
Action: Contact ASPCA APCC for any xylitol ingestion.
Acetaminophen (Tylenol and Paracetamol)
This is a critical feline-specific hazard. Cats have extremely limited glucuronyl transferase activity — they cannot safely metabolize acetaminophen at any dose. Acetaminophen produces toxic metabolites (N-acetyl-p-benzoquinone imine, NAPQI) that accumulate and cause:
- Methemoglobinemia: hemoglobin cannot carry oxygen; gums turn brown or grey
- Hepatocellular necrosis (liver cell death)
- Facial and paw edema (swelling)
Toxic dose: A single 325 mg regular-strength tablet is potentially fatal to an average cat. Even 10 mg/kg causes dangerous methemoglobinemia.
Symptom onset: 1-4 hours post-ingestion.
Symptoms: Muddy brown or grey gums, labored breathing, facial swelling, vomiting, hypothermia, jaundice
Action: Emergency veterinary care immediately. N-acetylcysteine and methylene blue treatments must be initiated rapidly.
Critical note: Never give a cat any human pain medication without specific veterinary guidance. This includes aspirin and ibuprofen as well as acetaminophen.
Serious Category: Significant Harm Possible
Onions and Garlic (All Allium Species)
All members of the Allium genus are toxic to cats — onions, garlic, leeks, chives, shallots, and scallions. Cats are more sensitive to organosulfur compound toxicity than dogs on a per-kilogram basis.
Mechanism: Organosulfur compounds oxidize hemoglobin to form Heinz bodies. Affected red blood cells are destroyed in the spleen (hemolytic anemia).
All forms are toxic: Raw, cooked, powdered, dehydrated. Powdered forms are more concentrated and more dangerous per gram. Garlic powder is especially hazardous.
Symptom onset: Anemia may not manifest for 3-5 days after ingestion. This delay can mislead owners into thinking a small exposure was harmless.
Symptoms: Lethargy, pale, yellow, or white gums, weakness, rapid heart rate, labored breathing, collapse, reddish-brown urine
Action: Contact ASPCA APCC for any allium ingestion. Blood transfusion may be required for severe anemia.
Permethrin
Permethrin is a pyrethroid insecticide used in many dog flea and tick spot-on treatments, certain yard and home insecticide sprays, and some permethrin-treated clothing.
This is not a food toxin, but it is one of the most common causes of severe cat poisoning and is included here because of its frequency and severity.
Mechanism: Cats lack sufficient activity of the CYP450 enzymes needed to metabolize pyrethroids. Permethrin causes persistent activation of sodium channels in neurons, producing continuous nervous system excitation.
Sources of exposure:
- Applying dog flea products directly to a cat
- A cat grooming a recently treated dog
- A cat entering an area that was sprayed with permethrin-containing insecticide
Symptom onset: Within hours of exposure.
Symptoms: Tremors (often severe, whole-body), hyperthermia, seizures, dilated pupils, inability to stand
Action: Emergency veterinary care immediately. Do not bathe the cat with cold water (can worsen hypothermia). Muscle relaxants (methocarbamol) and supportive care are the primary treatments.
Aspirin
As noted under the glucuronidation deficiency section, cats cannot metabolize aspirin safely. Even a single tablet causes gastrointestinal hemorrhage and progressive hepatotoxicity. Aspirin is occasionally prescribed by veterinarians at very specific doses for cardiac disease in cats (given once every 72 hours rather than daily), but this is strictly controlled medical use — it does not mean aspirin is safe for cats.
Symptoms: Vomiting (possibly bloody), anorexia, jaundice, ataxia, respiratory distress
Action: Emergency veterinary care immediately for any accidental aspirin ingestion.
Alcohol (Ethanol)
Cats are sensitive to ethanol and at greater risk than larger animals per unit dose. Even very small amounts cause rapid CNS and respiratory depression.
Sources: Alcoholic beverages, hand sanitizer, certain mouthwashes, unbaked yeast dough, fermented foods
Symptoms: Disorientation, drooling, vomiting, difficulty breathing, collapse
Action: Emergency veterinary care.
Raw Fish (Thiaminase)
Regular consumption of raw fish destroys thiamine (vitamin B1) through the action of thiaminase, a heat-sensitive enzyme present in many raw fish species. Thiamine is essential for normal neurological function.
Mechanism: Thiaminase cleaves the thiamine molecule, rendering it biologically inactive. Cats fed raw fish as a significant portion of their diet develop progressive thiamine depletion. Thiamine deficiency causes symmetric encephalopathy (brain disease) with characteristic neurological signs.
Symptom onset: Neurological signs after weeks to months of regular raw fish feeding. Acute crisis can appear faster with high-thiaminase fish.
Symptoms: Loss of balance, head tilting, walking in circles, inability to hold the head upright (ventroflexion of the neck), seizures, dilated pupils, death
Action: Thiamine-responsive; early treatment with thiamine supplementation and elimination of raw fish reverses signs. Severe cases may have permanent neurological damage.
Cooked fish is safe: Heat destroys thiaminase, making cooked fish perfectly acceptable.
Chocolate and Caffeine
Cats are theoretically more sensitive to theobromine on a per-kg basis than dogs, but in practice, cats rarely voluntarily consume chocolate due to their lack of sweet taste receptors. Caffeine ingestion (coffee grounds, tea, energy drinks) is more commonly reported.
Symptoms: Rapid heart rate, hyperactivity, vomiting, tremors, seizures
Action: ASPCA APCC immediately.
Grapes and Raisins
While most documented cases of grape/raisin nephrotoxicity involve dogs, the ASPCA Animal Poison Control Center recommends treating grape and raisin ingestion in cats as a potential emergency. Treat all exposures with urgency.
Essential Oils: A Feline-Specific Hazard
This category requires detailed coverage because of how commonly essential oils are used in homes (diffusers, cleaning products, topical products) and how poorly understood the risk is by many cat owners.
Cats lack efficient glucuronyl transferase enzymes and are unable to safely metabolize many phenolic and monoterpene compounds found in essential oils. The result is accumulation of toxic metabolites causing liver failure and neurological damage.
Essential oils documented as toxic to cats include:
- Tea tree oil (melaleuca): causes ataxia, tremors, liver failure; especially dangerous as topical product
- Eucalyptus oil: CNS depression, excessive salivation, seizures
- Citrus oils (lemon, lime, orange, grapefruit): GI upset, CNS depression, skin sensitization
- Pennyroyal: liver failure; historically used as flea repellent
- Clove and cinnamon oil: mucous membrane irritation, liver toxicity
- Thyme oil: liver toxicity
- Oregano oil: GI and liver toxicity
- Wintergreen and peppermint: high methyl salicylate content; metabolizes to salicylate (aspirin-like)
- Pine oil: CNS depression, liver and kidney toxicity
Exposure routes:
- Passive inhalation from diffusers (chronic low-level exposure)
- Direct skin contact from topical products
- Grooming oils off fur
Action: Remove the cat from exposure to diffusers. For skin exposure, wash gently with mild soap and water. Contact ASPCA APCC for any direct ingestion or if neurological signs appear.
Comprehensive A-Z Toxic Substances Reference Table for Cats
| Substance | Toxicity Level | Unique Cat Mechanism | Symptoms | Onset |
|---|---|---|---|---|
| Acetaminophen | Critical | Glucuronidation deficiency — methemoglobinemia | Brown gums, labored breathing, facial swelling | 1-4 hrs |
| Alcohol | Serious | CNS/respiratory depression | Disorientation, collapse, breathing difficulty | 30-60 min |
| Aspirin | Serious | Glucuronidation deficiency — GI bleeding, hepatotoxicity | Bloody vomit, anorexia, jaundice | 2-6 hrs |
| Caffeine | Serious | Methylxanthine toxicity | Rapid heart rate, tremors, seizures | 1-3 hrs |
| Chocolate | Moderate-Serious | Theobromine (rarely eaten voluntarily) | Rapid HR, vomiting | 6-12 hrs |
| Dog food (long-term) | Serious | Taurine deficiency | Cardiomyopathy, blindness | Months |
| Essential oils (multiple) | Serious-Critical | Glucuronidation deficiency | Ataxia, tremors, liver failure | Hours-days |
| Garlic (all forms) | Serious | Heinz body anemia — cats highly sensitive | Anemia, pale gums, weakness | 3-5 days |
| Grapes/raisins | Serious | Potential nephrotoxicity | Vomiting, kidney failure | 6-24 hrs |
| Lilies (Lilium/Hemerocallis) | Critical | Unknown nephrotoxin — all parts | Vomiting, kidney failure | 2 hrs - 72 hrs |
| Onions (all forms) | Serious | Heinz body anemia | Anemia, pale gums, weakness | 3-5 days |
| Permethrin | Critical | CYP450 deficiency — sodium channel activation | Severe tremors, seizures | Hours |
| Raw fish (regular) | Serious | Thiaminase destroys thiamine (B1) | Neurological signs, vestibular disease | Weeks-months |
| Raw egg whites (regular) | Moderate | Avidin blocks biotin | Dermatitis, hair loss, neurological | Weeks |
| Xylitol | Serious | Potential hypoglycemia | Weakness, vomiting | 30-60 min |
Plants Toxic to Cats: Quick Reference
Many common houseplants and cut flowers are toxic to cats. Beyond lilies, the following are most commonly involved in cat poisonings:
Highly dangerous:
- Lily of the valley (Convallaria): cardiac glycosides — arrhythmias
- Sago palm (Cycas): cycasin — liver failure (also critical in dogs)
- Oleander (Nerium): cardiac glycosides
- Autumn crocus (Colchicum): colchicine — multi-organ failure
- Foxglove (Digitalis): cardiac glycosides
- Rhododendron/Azalea: grayanotoxins — CNS and cardiac
Moderately dangerous (GI and other effects):
- Pothos/Philodendron: calcium oxalate crystals — oral/GI irritation
- Dieffenbachia: calcium oxalate crystals
- Peace lily (Spathiphyllum): calcium oxalate — oral irritation (NOT kidney failure)
- Aloe vera: anthraquinones — diarrhea, lethargy
- English ivy: triterpenoid saponins — GI upset, CNS signs
Emergency Response Protocol for Cat Poisoning
"Cats are frequently exposed to toxins through grooming contaminated fur — this means topical exposures are as dangerous as ingestion. Always check the cat's fur and paws as well as what it may have eaten." — Volmer, P. A., Veterinary Toxicology, 2012
Immediate steps:
Identify the substance if possible. Check packaging. Note the product name, active ingredients, and concentration.
Call immediately: ASPCA APCC: 888-426-4435 Pet Poison Helpline: 855-764-7661
Do not induce vomiting without guidance. This is especially critical for cats — cats are more prone to aspiration and the emetic agent of choice in veterinary settings (dexmedetomidine) is different from what is used in dogs.
For topical exposure: If the substance is on the cat's fur or skin, gently wash with a mild soap (dish soap works) to prevent further grooming ingestion. Use lukewarm water — never cold, which can cause hypothermia.
Do not give any human medications to reduce symptoms. Ibuprofen, acetaminophen, and aspirin are all toxic to cats.
Transport carefully: A poisoned cat may be distressed, confused, or seizuring. Use a carrier or wrap gently in a towel to reduce injury during transport.
Related Articles
- What Can Cats Eat
- How Much to Feed a Cat by Weight
- Wet vs Dry Cat Food: Which Is Better
- Foods Toxic to Dogs Complete List
- What Can Dogs Eat
References
- ASPCA Animal Poison Control Center. (2024). Animal Poison Control Center Resources. https://www.aspca.org/pet-care/animal-poison-control
- Cortinovis, C., & Caloni, F. (2016). Household food items toxic to dogs and cats. Frontiers in Veterinary Science, 3, 26. https://doi.org/10.3389/fvets.2016.00026
- Volmer, P. A. (2012). Veterinary Toxicology: Basic and Clinical Principles (2nd ed.). Elsevier.
- DeClementi, C., & Sobczak, B. R. (2012). Common rodenticide toxicoses in small animals. Veterinary Clinics of North America: Small Animal Practice, 42(2), 349-360.
- Langston, C. E. (2002). Acute renal failure caused by lily ingestion in six cats. Journal of the American Veterinary Medical Association, 220(1), 49-52. https://doi.org/10.2460/javma.2002.220.49
- Richardson, J. A. (2000). Management of acetaminophen and ibuprofen toxicoses in dogs and cats. Journal of Veterinary Emergency and Critical Care, 10(4), 285-291.
Frequently Asked Questions
What is the most dangerous plant for cats?
True lilies (Lilium and Hemerocallis species) are the most dangerous common household plants for cats. All parts — petals, leaves, pollen, stems, and even the water in a vase — are severely nephrotoxic. A cat that licks lily pollen off its fur can develop fatal kidney failure within 72 hours. Easter lilies, tiger lilies, Asiatic lilies, and stargazer lilies are all included. Remove all true lilies from any home with cats.
Why can't cats have essential oils?
Cats lack specific liver enzymes (glucuronyl transferases) that metabolize phenolic compounds found in many essential oils. Without these enzymes, toxic metabolites accumulate. Tea tree oil, eucalyptus, citrus oils, pennyroyal, cinnamon, clove, and others cause liver failure, neurological damage, and death in cats. Even passive exposure from diffusers can harm cats over time.
Is permethrin toxic to cats?
Yes — permethrin is severely neurotoxic to cats. It is commonly found in dog spot-on flea treatments and some tick sprays. Cats exposed to permethrin (from being treated directly or grooming a dog treated with permethrin) develop tremors, seizures, hyperthermia, and can die without immediate veterinary treatment. Never apply dog flea products to cats.
Can cats eat tuna?
Cooked tuna in small amounts as an occasional treat is generally safe. However, raw tuna contains thiaminase, which destroys thiamine (B1) and can cause neurological disease. Exclusive feeding of tuna depletes vitamin E and causes steatitis. Tuna should not be a dietary staple — it is a treat, not a complete food.
Is aspirin safe for cats?
No. Aspirin is highly toxic to cats. Cats have severely limited glucuronyl transferase activity, which is needed to metabolize aspirin. Even a single adult aspirin tablet (325 mg) can cause severe gastrointestinal hemorrhage and hepatotoxicity in a cat. Aspirin is sometimes prescribed at very low doses by veterinarians in specific cardiac conditions, but only under strict supervision.
Can cats eat dog food?
Occasional accidental dog food consumption will not harm a cat, but dog food fed as a primary diet is dangerous long-term. Dog food lacks adequate taurine for cats, causing dilated cardiomyopathy and blindness over months. It also lacks arachidonic acid and adequate pre-formed vitamin A for cats' obligate carnivore needs.