Blood in vomit means the corrosion has begun
Your 3 kg cat’s stomach lining is thinner than a dog’s—iron tablets start burning through it fast, especially after chewing released the full dose. The red streaks or coffee-ground vomit you’re seeing are stomach tissue and blood mixing with acid. This isn’t mild irritation; it’s ulceration that can perforate within hours without treatment.
Cats mask pain instinctively, so if she’s visibly vomiting blood, the damage is advanced. Her small size makes blood loss critical—just a few teaspoons can send her into shock. The vet will likely give her IV fluids immediately to stabilize her before addressing the iron itself.
Six hours in is the deceptive danger zone
Iron poisoning’s first phase (0–6 hours) involves direct stomach damage—what you’re seeing now. But the next 12–48 hours are when absorbed iron attacks the liver. She might stop vomiting temporarily, tricking you into thinking she’s improving, while her organs are actually failing internally.
Her tiny liver filters toxins poorly compared to dogs. The vet may use chelation therapy to bind circulating iron before it overwhelms her system, but this requires hospitalization. Blood tests now check her red cell count (for hemorrhage) and liver enzymes—cats often crash faster than dogs.
Why her weight changes everything
A 3 kg cat eating one human iron tablet is like a person swallowing 20 pills at once—the dose per pound is staggering. Even if she vomited some up, absorbed iron could already be at toxic levels. The vet needs to calculate exactly how many milligrams per kilogram she ingested based on the supplement’s label.
Watch for pale gums, rapid breathing, or lethargy—signs she’s losing blood internally or going into shock. Cats with iron poisoning often develop arrhythmias from electrolyte imbalances caused by vomiting. Her team may need to correct these with IV potassium or magnesium.
The critical 24-hour window after bloody vomit
If she survives the initial corrosion phase, days 2–4 bring liver failure risks. The vet will monitor her bilirubin levels (jaundice indicator) and clotting factors—iron destroys these first. She may need plasma transfusions if her blood won’t clot properly.
Ask about repeat X-rays. Iron tablets sometimes clump together in the stomach, causing ongoing damage even after vomiting. Surgery becomes an option if they haven’t passed into the intestines by 12 hours post-ingestion—but this is high-risk for a cat her size.
The step-by-step response, from the first minute to the vet visit, is in our Iron Supplements & Prenatal Vitamins emergency guide.