A 10 mg THC gummy is 2.5 mg per kg for a 4 kg cat, and that is enough to put most cats on the floor for 12-24 hours. The 2-hour onset is the trap: the cat looks normal for the first hour, the owner goes to bed, and the worst of it lands at hour 3 with nobody watching. Three things must not happen at home — no induced vomiting, no fat or milk, and no leaving the cat alone to sleep it off.
Two product classes, two very different risks
Class 1, THC edibles. Gummies at 5-10 mg per piece, chocolate bars at 10-100 mg per bar, baked goods made with cannabutter at 10-50 mg per serving, tinctures at 5-25 mg per mL. Labels are commonly off by 20-50% in either direction, and homemade butter carries no label at all.
Class 2, CBD and hemp products. Oils at 5-25 mg per mL, soft chews, topicals. THC is capped near 0.3% by law, so a 10 mL bottle holds under 30 mg — a different order of exposure. CBD is not benign either: vomiting, loose stool and raised liver enzymes are the usual calls, and CBD competes for the enzymes that clear other drugs.
Vape cartridges belong to neither class: nicotine at 3-5% plus propylene glycol, absorbed through the gums of a cat that bites one.
Dose math: 10 mg is a lot for a cat
Most cats show signs at 1-3 mg per kg, so a 4 kg cat reacts to 4-12 mg. One 10 mg gummy sits inside that range; 2 gummies, or a corner of a 100 mg chocolate bar, is 3-5 times the threshold. A 3 kg cat eating half of a 20 mg brownie takes 3.3 mg per kg. There is no cat-labeled dose of THC, so treat any edible as a poisoning until a vet says otherwise.
Kittens and seniors drop faster. One 10 mg gummy against 1 kg of body weight is 10 mg per kg, and a 12-year-old with kidney disease clears the drug more slowly.
Why 2 hours is the number to set a clock by
Oral THC is absorbed over 30-120 minutes and peaks at 2-4 hours; a fatty vehicle such as chocolate or peanut butter pushes the peak later still. Cats glucuronidate poorly, the liver step that clears THC, so the effect runs 12-24 hours and can reach 36 hours after a large dose. That is about 3 times the duration in a dog, and why a cat sent home at hour 6 can come back at hour 20.
The 0, 30-minute, 2-hour, 6-hour, 24-hour timeline
| Hours | What the cat looks like | Numbers that matter | Do now |
|---|---|---|---|
| 0 | Normal, crumbs on the floor, wrapper open | 10 mg is 2.5 mg/kg for a 4 kg cat | Pick up every crumb, bag the wrapper |
| 0.5 | Still normal, or a little quiet | Onset window 30-120 minutes | Carrier ready, no food, call the clinic |
| 2 | Pupils wide and fixed, wobbly, staring at nothing | 1-3 mg/kg threshold now passed | Exam, blood glucose, temperature |
| 6 | Tremors, cold ears, urine dribbling, cannot stand | Temperature under 37°C, rate 100-140 | Warm, fluids, continuous monitoring |
| 24 | Sleepy but responsive, eating a little | Effects run 12-24 hours, up to 36 | Recheck; keep watching to 48 hours |
Signs, by grade
Mild, 1-2 mg per kg. Dilated pupils that do not narrow in bright light, a fixed stare, unsteady walking, 1-2 vomits, drooling. The cat is high, not dying, and it still needs a temperature and glucose check.
Moderate, 2-5 mg per kg. Tremors, hyperesthesia — the cat flinches when touched or hears a bag rustle — a heart rate of 100-140, a temperature of 36-37°C, urine leaking without control, head pressing into a corner. This grade needs a clinic, warmth and fluids.
Severe, 5 mg per kg and up. Temperature under 36°C, unresponsive to voice, slow shallow breathing, seizures, blood glucose under 3.9 mmol/L, or aspiration after a vomit. Seizures are uncommon with THC alone, which is why a seizure means looking for the other thing in the bite.
Three things not to do
- Do not induce vomiting. Onset is already 30-120 minutes, so most of the drug is absorbed before anything comes up; a cat that is ataxic or trembling cannot protect its airway, and a chocolate or gummy vomit is the classic aspiration. There is no home emetic with a cat-labeled dose.
- Do not give fat, milk, oil or peanut butter. THC is fat-soluble, and a spoon of butter or cream raises absorption instead of diluting it. Milk also adds a lactose load to a cat that is already nauseated.
- Do not leave the cat alone to sleep it off, and do not give human drugs. Hypothermia, aspiration and hypoglycemia all happen in an unattended cat, and a human anti-emetic or a stimulant adds a second poisoning. Keep the cat warm, in sight, on a flat surface.
What else is in the same bite
Chocolate is the usual co-toxin. Milk chocolate holds about 2.2 mg of theobromine per gram, dark chocolate 5-8 mg, and baker's chocolate 16 mg; the theobromine threshold in a cat is roughly 20 mg per kg, so a 4 kg cat reaches 80 mg at 36 g of milk chocolate or 5 g of baker's. Gummies may also carry xylitol, and a baked edible carries butter, sugar and raisins. Read the whole label, not just the THC number — plant poisonings punish the same shortcut.
What the clinic does, by name only
Activated charcoal inside 1-2 hours if the cat can swallow and protect its airway. Intravenous crystalloids, active warming to 37-38°C, and glucose checked on every set of vitals. Maropitant for vomiting, diazepam for tremors and seizures, intravenous lipid emulsion for a massive dose that will not stabilise. Continuous ECG and temperature for the first 12 hours, and a recheck of liver and kidney values at 24-48 hours. There is no antidote for THC; everything above is prescription, weight-dosed, and decided by the vet. The toxin index covers the rest.
Where the exposure comes from
A handbag on the floor, a bedside drawer, a jar with no child lock, a plate left on the coffee table after a party. Cats go for the fat and sugar, not the THC, and one gummy under the sofa is a second exposure 2 days later.
First 10 minutes, in order
- Find the package and read mg per piece, pieces per package and the THC percentage. Photograph the label.
- Estimate what is missing, weigh the cat, and divide: mg eaten divided by kg of cat.
- No vomiting, no butter, milk or oil, and no human medication of any kind.
- Put the cat on a flat bed in a 22-24°C room, cover it with a light blanket, and keep it in sight.
- Call and go if the dose is over 2 mg per kg, the temperature is under 37°C, the cat cannot stand, or chocolate was involved. Bring the wrapper and the remaining pieces.
Frequently asked
My cat ate half a 10 mg THC gummy. How worried should I be?
That is 5 mg, or 1.25 mg per kg for a 4 kg cat — the mild end, where dilated pupils and a wobbly walk are expected but the cat should still be checked. Keep it warm, do not induce vomiting, and call the clinic with the weight and the exact mg. Most cats are back to normal in 12-24 hours.
Is CBD oil safe for a cat?
Not automatically. THC is capped near 0.3% in hemp products, so the exposure is far smaller than an edible, but CBD itself causes vomiting, loose stool and raised liver enzymes in cats, and it competes with the enzymes that clear other drugs. Doses from a bottle are labels, not prescriptions.
Why does my cat seem worse at hour 6 than at hour 2?
Edible THC peaks at 2-4 hours and cats clear it slowly, so effects run 12-24 hours and can last 36. A fatty vehicle delays the peak further. Worsening at hour 6 means temperature, glucose and breathing need checking, not that the cat is dying from the gummy alone.