Cats
Potentially toxicConsulted references classify the plant as toxic or irritating for that pet type.
Verified against ASPCA/provenance audit 2026-05-06 on May 6, 2026.
Sources
cat safety reference
Is Onion safe for cats?
Allium cepa
The onion is a bulbous vegetable widely used in cooking that contains compounds capable of damaging red blood cells in pets. Ingestion of any part of the plant, including the bulb, can lead to serious health complications.
Allium cepaBulb OnionGarden OnionOnion
- Light
- Full sun
- Habit
- Bulbous herb
- Care
- Moderate
Safety status
What this means for your cat
Cats are the species most susceptible to onion toxicity. The N-propyl disulfide in onion damages feline red blood cells and causes Heinz-body hemolytic anemia, and even small amounts of cooked, raw, dehydrated, or powdered onion can poison a cat.
What to watch for
Vomiting and reduced appetite usually appear first. As red blood cells break down, watch for weakness, lethargy, pale or yellow gums, rapid breathing or panting, an elevated heart rate, and brown- or red-tinged urine.
Time window
Heinz bodies and methemoglobin can appear in bloodwork within 24 hours of ingestion, but the visible signs of anemia may take several days to develop. Don't wait for symptoms before calling.
When to call the vet
Call your vet or ASPCA Poison Control (888-426-4435) any time you suspect ingestion — even a small bite. Concentrated forms (onion powder, dehydrated flakes, dry soup mixes) are especially dangerous and warrant an immediate call.
First aid at home
Remove any remaining onion or onion-containing food, then call ASPCA Poison Control or your vet for guidance. Do not induce vomiting at home — Pet Poison Helpline cautions that unsupervised home emesis is one of the most common pet-poisoning first-aid mistakes.
Sources: ASPCA, Pet Poison Helpline, Merck Veterinary Manual.
If a pet has chewed or swallowed plant material and is showing symptoms, contact a veterinarian or poison resource immediately. This product is for structured reference, not diagnosis.
Cats — concern notes
Common signs
Vomiting, diarrhea, lethargy, pale gums, and rapid breathing.
Escalation note
Ingestion can cause oxidative damage to red blood cells, leading to hemolytic anemia. Please contact your veterinarian or an animal poison control center immediately if ingestion is suspected.
Safer alternatives
No hand-picked alternatives for this plant yet. You can still pick your own using the Compare button on any other plant.
Source evidence
ASPCA Toxic Plant List
toxicology · 99% reliability
Onion is toxic to both cats and dogs, causing damage to red blood cells.
NC State Extension Plant Toolbox
botanical · 94% reliability
Allium cepa is a biennial herb grown as an annual for its edible bulb.
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