Adderall, Vyvanse, Ritalin and Concerta are the four names behind almost every ADHD pill a cat finds on a nightstand, and one 10 mg tablet is 2.5 mg/kg for a 4 kg cat, already inside the band where tremors and a temperature above 40 degrees Celsius appear. Signs start within 30 minutes on an empty stomach. Nothing you do at home removes the drug; the job is to stop it getting worse and be at a clinic inside 60 minutes.
Two classes, and the extended-release trap
Class 1 is amphetamine: Adderall as mixed amphetamine salts at 5 to 30 mg per tablet, Vyvanse as lisdexamfetamine at 10 to 70 mg per capsule. Class 2 is methylphenidate: Ritalin at 5 to 20 mg, Concerta at 18 to 54 mg. Amphetamine pushes dopamine and noradrenaline out of the nerve terminal; methylphenidate blocks their reuptake.
The immediate-release forms peak at 1 to 2 hours and are mostly cleared by 6. The extended-release forms are the trap. Concerta uses an osmotic shell that releases over 10 to 12 hours, and Vyvanse is a prodrug that red blood cells must convert before it does anything, which pushes the peak to 3 or 4 hours. A cat that looks normal at 90 minutes after swallowing a 36 mg Concerta can be tremoring at hour 5.
The dose arithmetic that decides the night
Veterinary toxicology groups the thresholds into bands rather than single numbers. Under 1 mg/kg: restlessness, a heart rate above 200 beats per minute, dilated pupils. From 1 to 3 mg/kg: tremors, vomiting, pacing that does not stop. Above 3 mg/kg: a temperature over 40 degrees Celsius, seizures, arrhythmia. Above 10 mg/kg: death is a real risk without intensive care. Divide the milligrams on the label by the kilograms on the scale before you call, because that one number changes the answer you get.
| Product | Tablet (mg) | mg/kg in a 4 kg cat | Expected signs | Onset |
|---|---|---|---|---|
| Adderall IR | 10 | 2.5 | Tremor, pacing, heart rate 220 | 30-60 min |
| Adderall XR | 20 | 5.0 | Temperature over 40 C, agitation | 60-120 min |
| Vyvanse | 30 | 7.5 | Seizure risk, rigid limbs | 2-4 h |
| Ritalin | 10 | 2.5 | Restlessness, dilated pupils | 20-40 min |
| Concerta | 36 | 9.0 | Severe, needs ICU level care | 3-6 h |
A 3 kg cat doubles the stakes: the same 10 mg tablet is 3.3 mg/kg, and a 20 mg tablet is 6.7 mg/kg. Dose per kilogram, not tablets swallowed, is what the vet asks for.
30 minutes to the first sign
On an empty stomach, immediate-release amphetamine shows its first effect at 30 minutes, sometimes 20. The order is fairly predictable: restlessness and pacing, then pupils that stay wide in bright light, then drooling, then a fine tremor in the hind legs that becomes a whole-body shake.
Take a rectal temperature, not an ear reading. At 39.5 degrees Celsius start active cooling, at 40.5 go to a clinic now, and above 41.5 the risk of clotting problems and kidney injury climbs fast. A resting heart rate above 240 beats per minute, or an irregular rhythm, means the drug is acting on the myocardium and the cat should not sit at home waiting for the peak to pass.
Four things not to do
- Do not make the cat vomit. Hydrogen peroxide, salt water and fingers down the throat are all out: a stimulant-loaded cat can seize mid-vomit, and aspirated vomit turns one emergency into two.
- Do not give milk, oil, vinegar, charcoal or any home binder. Charcoal is dosed by a vet at 1 to 3 g per kg and only inside the first 60 to 120 minutes; a home dose either does nothing or pulls fluid into the gut.
- Do not use a human sedative or antihistamine to calm the cat. Diphenhydramine and similar drugs add to the tachycardia and the disorientation, and a human tranquilizer can drop blood pressure in an animal that is already hyperthermic.
- Do not try to burn it off with exercise or an ice bath. Cold water on a cat at 40.5 degrees triggers shivering, which produces more heat, and forced movement in a tremoring cat raises the risk of muscle breakdown.
Cooling that works and cooling that backfires
Wet the paws, the groin and the ear pinnae with tap water at 20 to 25 degrees Celsius, put the cat in front of a fan, and recheck the rectal temperature every 10 minutes. Stop at 39.5 degrees Celsius, because a 4 kg animal overshoots into hypothermia easily. No ice packs on the skin, no alcohol rub, and no wet cat in a cold room.
What the clinic does, by name
Care is prescription-only and begins with decontamination if the cat arrives inside 60 minutes. After that you may hear these names: activated charcoal, diazepam or midazolam for tremor and seizure control, intravenous fluids at 2 to 4 ml per kg per hour, and a beta blocker such as esmolol or propranolol when the rate stays above 240. Each one is given by a veterinarian on a prescription, at a dose worked out from the weight on the clinic scale, which is why an owner's guess is never used.
The 6 hour and 24 hour tail
Immediate-release tablets are largely cleared by 6 hours, but the cat is not: poor sleep, no appetite and a resting rate near 200 can run 12 to 24 hours. Extended-release forms keep the window open to 12 hours and Vyvanse to about 14. Muscle breakdown shows up late, as dark cola-coloured urine at 12 to 48 hours, so urine output is measured at 1 to 2 ml per kg per hour; cats that need that monitoring sometimes go home with a catheter, and the care for one is set out in catheter aftercare.
Timeline from the tablet to 24 hours
| Time | What is happening | What you measure | Threshold |
|---|---|---|---|
| 0-10 min | Bag the bottle, write the time | mg on label, kg on scale | mg/kg total |
| 30 min | First clinical signs | Rectal temperature, heart rate | 39.5 C, 200 bpm |
| 2 h | Immediate-release peak | Pupil size, tremor, gait | 240 bpm |
| 6 h | Most of an IR dose cleared | Appetite, ability to walk | under 39.5 C |
| 24 h | Extended-release tail, urine colour | Urine output, water intake | 1-2 ml/kg/hour |
Do this now
- Count what is missing from the bottle and write the number down with the clock time.
- Weigh the cat on a kitchen scale, then divide the milligrams by the kilograms.
- Take a rectal temperature and a 15 second heart count, multiply by 4, and note both.
- Call the clinic, say the drug name, the mg/kg and the minute of ingestion, then drive.
- Bag the bottle and the blister pack, cool the paws on the way, and do not stop for food or water.
If the pill was in a houseplant saucer or mixed with plant material the cat also chewed, check plant poisoning as well, and compare the substance against the toxic dose tool before you decide to wait.
Frequently asked
My cat licked half a 10 mg Adderall. Is that an emergency?
Assume yes and call now, because half a tablet is 1.25 mg/kg in a 4 kg cat, which sits in the band where pacing, dilated pupils and a heart rate above 200 beats per minute appear within 30 minutes. Bring the bottle so the vet can read the salt form and the milligram count, and take a rectal temperature before you leave the house.
Can I just watch it at home if the cat seems calm after an hour?
No, because the peak of an immediate-release tablet is at 1 to 2 hours and an extended-release product such as Concerta keeps releasing for 10 to 12 hours. A calm cat at 60 minutes can be tremoring at hour 5, so the safe plan is an exam within 2 hours, a rectal temperature every 30 minutes at home, and an immediate return if the rate passes 240 or the temperature passes 40.5 degrees Celsius.
Why will the vet not just give charcoal and send us home?
Charcoal only binds drug that is still in the gut, which means the first 60 to 120 minutes, and it is dosed at 1 to 3 g per kg by a vet who has checked for tremor and a safe swallow. After that window the drug is already in the blood, so the work is cooling, fluids, sedation for tremor, and heart rate control, all prescription drugs with doses calculated from the clinic scale weight.