Safety verdict
Consulted references classify the plant as toxic or irritating for that pet type.
Pet ingestion lookup
My cat ate Onion - what should I do?
Allium cepa
Potentially toxic
Contact your veterinarian or an animal poison-control resource now, especially if any amount was chewed or swallowed.
Verified against ASPCA/provenance audit 2026-05-06 on May 6, 2026.
Signs to watch for
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.
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.
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.
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.
Sources: ASPCA, Pet Poison Helpline, Merck Veterinary Manual.
Source references
Poison-control resources
This page summarizes source-bound plant-safety information and is not veterinary advice.