Emergency guide

My dog ate macadamia nuts — what do I do?

Reviewed by Petcro Veterinary Editorial Desk May 14, 2026

Macadamia nuts are one of the few common toxins where vets honestly say 'we do not yet know exactly why'. The mechanism remains unidentified. The good news: macadamia toxicity in dogs is usually NOT fatal. The bad news: it is miserable. Hind-leg weakness, tremors, and fever can hit within 12 hours from as little as 2 grams of macadamia per kg of body weight. Call your vet now.

EmergencyASPCA Animal Poison Control (US, 24/7): (888) 426-4435

Signs to watch for

Hind-leg weakness or inability to stand (the most characteristic sign)
Tremors or muscle twitching
Hyperthermia (elevated body temperature, often above 103°F / 39.4°C)
Ataxia (uncoordinated walking, stumbling, drunk-like gait)
Vomiting
Depression, lethargy, reluctance to move
Stiff or painful joints, pain on touch

Timeline

First 2 hours

Best decontamination window. If your dog ate a known dose and was seen within 2 hours, vets can induce vomiting (apomorphine) and give activated charcoal — much easier than treating symptoms after they peak.

6–12 hours

Onset of clinical signs. Hind-leg weakness is often the first thing owners notice — dogs sit down and seem unable or unwilling to use their back legs. Vomiting and lethargy can appear at the same time.

12–24 hours

Peak symptoms. Body temperature rises, tremors may be visible, ataxia (drunken-walk staggering) is common. This is usually when dogs are admitted for IV fluids and supportive care.

24–48 hours

With supportive care, most dogs start improving in this window. Temperature normalizes first, then strength returns.

48–72 hours

Most dogs are essentially back to normal by 72 hours. Lingering mild weakness or soreness for a few more days is common.

Why are macadamia nuts toxic to dogs?

The honest answer: nobody knows yet. Macadamia toxicity in dogs has been documented since the 1990s, with hundreds of cases in the literature, but the specific toxin and mechanism remain unidentified. Researchers have ruled out the common nut allergens and mycotoxin / mold contamination (including aflatoxins). The leading hypothesis is a compound unique to Macadamia integrifolia / tetraphylla, but it has not been isolated.

What is clear: only dogs are reliably affected at low doses. Cats appear less sensitive (data is limited). Humans, birds, and other mammals do not show the syndrome. The dog-specificity is one of the reasons the toxin search has been hard — fewer animal models reproduce it.

Practical implication: there is no antidote and no specific test. Treatment is supportive — IV fluids, antiemetics, temperature management, sometimes anti-inflammatories. The good news is that the syndrome is almost always self-resolving with care.

How many macadamia nuts is too many?

The published toxicity threshold is roughly 2 grams of macadamia per kg of dog body weight. A single macadamia nut weighs about 2 grams, so:

For a 10 kg (22 lb) dog: roughly 10 nuts can produce symptoms. For a 5 kg toy breed: roughly 5 nuts. For a 30 kg lab: roughly 30 nuts — but a curious lab can easily clear an open bowl. Doses well above the threshold may produce more severe signs, but the syndrome ceiling is much lower than with chocolate or xylitol — most cases follow a similar 24–48 hour course regardless of exact dose.

A 25 g serving (a small handful) of mixed nuts that contains macadamias can hit threshold for a small dog. Be specific when you call the vet — "a handful of trail mix" is less useful than "she ate about 8 macadamia nuts plus some raisins".

What to do right now

1. Call your vet or the ASPCA Animal Poison Control ((888) 426-4435, 24/7) immediately. Have your dog's weight, how many nuts were eaten, and the time of ingestion ready.

2. Note whether any chocolate was involved — chocolate-covered macadamia nuts stack two toxins and the clinical picture is worse than either alone. The vet will triage differently.

3. Do not induce vomiting at home unless your vet specifically tells you to. Macadamia syndrome is rarely fatal — the risk of aspiration from at-home emesis is not worth it.

4. Bring the package or note the type if you can — raw, roasted, salted, chocolate-covered, brittle, cookie, ice cream. Each changes the dose and the second-toxin picture.

5. If you cannot reach a vet within an hour and your dog is showing severe tremors or cannot stand, drive to the nearest emergency vet. Supportive care started early shortens the misery substantially.

What hind-leg weakness actually looks like

Hind-leg weakness is the single most recognizable macadamia sign — vets often suspect macadamia poisoning before bloodwork comes back, just from the presentation. What owners describe: the dog sits down and refuses to stand, or stands but immediately collapses on the back end, or walks with the rear legs splayed and dragging.

This is NOT paralysis — your dog still has sensation and voluntary control of the legs. The weakness is in the strength to support body weight: the dog tries to walk, the hind end gives out, the dog tries again, same result. The technical term is paraparesis (weakness of both hind legs), and it is reversible.

Important: hind-leg weakness from macadamia is bilaterally symmetric — both back legs are affected equally. If only ONE leg is weak, that is more likely a back injury or one-sided neurological problem — different emergency, same urgency.

The chocolate-covered macadamia danger

Chocolate-covered macadamia nuts are a real-world overdose scenario that vets see every holiday season. The dog gets two toxins simultaneously: theobromine from the chocolate AND the macadamia toxin. Symptoms compound — the chocolate cardiovascular signs (rapid heart rate, restlessness) plus the macadamia neurologic signs (hind-leg weakness, tremors, hyperthermia).

Practical triage: if chocolate is in the mix, treat as a chocolate emergency first. Use our chocolate-toxicity calculator for the theobromine dose, then add the macadamia syndrome on top. The combination warrants more aggressive intervention than either alone.

See the chocolate emergency guide for full first-aid steps on the chocolate side of the picture.

What not to do

Do not assume "just a few nuts" is fine. The 2 g/kg threshold is reached fast for small dogs — five nuts can do it for a toy breed.
Do not induce vomiting at home without vet guidance. Aspiration risk and ataxia (if signs have started) make at-home emesis a poor trade.
Do not give chocolate-covered macadamia nuts as a treat ever. The combination is worse than either toxin alone.
Do not dismiss the syndrome because "macadamia is rarely fatal". The misery is severe and IV fluids cut the recovery from 72+ hours to roughly 48.
Do not skip the vet call hoping symptoms fade. Hyperthermia and tremors are uncomfortable enough that supportive care matters even when the prognosis is good.

Frequently asked

Will my dog die from eating macadamia nuts?

Macadamia toxicity in dogs is usually NOT fatal — that distinguishes it from grapes, xylitol, and chocolate at toxic dose. The syndrome is miserable (hind-leg weakness, tremors, hyperthermia for 24–48 hours) but almost always self-resolving with supportive care. Fatalities are rare and usually involve compounding factors like dehydration or coexisting chocolate ingestion.

How many macadamia nuts is too many?

The threshold is roughly 2 grams of macadamia per kg of dog body weight. One nut weighs about 2 g, so a 10 kg dog can show symptoms from about 10 nuts. A 5 kg toy breed needs only 5 nuts. Larger doses do not seem to scale proportionally to worse outcomes — once threshold is hit, the syndrome runs its course.

What about macadamia nut butter?

Same toxin, often more concentrated through the grinding process. The bigger concern: many "no-sugar-added" or "keto-friendly" nut butters use xylitol as a sweetener, which stacks a separate (and worse) emergency on top of the macadamia syndrome. Always check the label.

Why do vets not know exactly what makes macadamias toxic?

Macadamia toxicity has been studied since the 1990s but the specific compound has eluded researchers. Common nut allergens, mycotoxins (mold contamination), and aflatoxins have all been ruled out. The dog-specificity (cats, humans, and other species do not show the syndrome) makes the toxin hard to study because few animal models reproduce it. Honest 'we don't know yet' is the current state.

Are roasted or salted macadamia nuts safer?

No. The toxin appears stable under roasting and salting. Salted versions add a sodium load on top of the macadamia syndrome — not enough to be salt-toxic in normal amounts, but unhelpful for a dog already vomiting and dehydrated.

My dog ate macadamia hours ago and seems fine — when do I stop watching?

Onset of clinical signs is typically 6–12 hours after ingestion. If 24 hours have passed with NO symptoms (no hind-leg weakness, no tremors, normal temperature, normal eating), your dog is essentially clear. The syndrome rarely first appears beyond 24 hours.

My dog ate chocolate-covered macadamia nuts — is it worse?

Yes — significantly. Chocolate (theobromine) and macadamia toxin stack: cardiovascular signs from chocolate plus neurologic signs from macadamia. Treat as the more severe of the two emergencies, usually the chocolate side first (use the chocolate-toxicity calculator for the theobromine dose), then add macadamia syndrome management.

Primary sources

This guide draws on the following authorities. Specific clinical decisions for your pet should always be made with your vet.

Need more help?

Double-check another food, get a personalised follow-up, or talk to CRO about your pet’s specific situation.

Check another item Chocolate emergency guide Chocolate toxicity calc

This guide is educational and based on US veterinary sources (ASPCA APCC, AVMA, and peer-reviewed literature). It is not a substitute for a vet call. When in doubt, phone your vet or the ASPCA Animal Poison Control — the fee is far cheaper than a delayed case.