Macadamia allergy
Tree-nut allergy to macadamia nuts.
About macadamia allergy
Macadamia is a tree nut native to Australia, rich and buttery, and used in cookies, chocolates and snacks. Allergy to macadamia is less common than to some other tree nuts but is well recognised and can be serious. It is IgE-mediated: the immune system makes antibodies to macadamia proteins, and eating the nut triggers a rapid release of histamine and other chemicals that cause the reaction. As with other nuts, sensitisation can develop in childhood or adulthood and often persists.
Reactions usually come on quickly, often within minutes. Symptoms can include an itchy mouth, hives, swelling of the lips and face, vomiting, wheeze, throat tightness and, in serious cases, anaphylaxis, which can be life-threatening. Tree nuts share some proteins and are often processed and packaged together, so people allergic to macadamia may react to, or be advised to be cautious with, other tree nuts, and cross-contamination in manufacturing is a genuine concern. Being allergic to one nut does not guarantee reactions to all, but specialist assessment is important.
Diagnosis combines your history with skin-prick or specific-IgE testing, sometimes with component testing, and occasionally a supervised challenge. Management is avoidance, careful label-reading and attention to "may contain nuts" warnings on chocolates, baked goods and snack mixes. Anyone at risk of anaphylaxis should carry an adrenaline auto-injector and know how to use it. A severe reaction is a medical emergency: use the injector and call 999 immediately.
Common triggers
- Macadamia and products containing it
Symptoms
- Itching or tingling in the mouth
- Hives, itching or eczema
- Swelling of the lips, face, tongue or throat
- Stomach cramps, nausea, vomiting or diarrhoea
- Wheezing or trouble breathing
- In severe cases, anaphylaxis
Avoidance & management
- Read ingredient labels every time
- Ask about ingredients and cross-contamination when eating out
- Keep the food out of shared cooking areas
- Carry prescribed antihistamines or an adrenaline auto-injector
- Seek emergency help for any severe reaction
Sources & references
Allergy safety: what everyone should know
Mild-to-moderate reaction signs
- Itching, hives or a raised rash
- Swelling of lips, face or eyes
- Tingling mouth, sneezing, runny nose
- Stomach pain, nausea or vomiting
Anaphylaxis — call 999 (UK) or 112 (EU) immediately
- Difficult or noisy breathing, wheeze, persistent cough
- Swelling of the tongue or tightness in the throat
- Dizziness, collapse, pale and floppy (young children)
- Use an adrenaline auto-injector (e.g. EpiPen) at once if prescribed, then call an ambulance even if symptoms improve
Allergy or intolerance? A true allergy involves the immune system and can escalate quickly; an intolerance (e.g. lactose intolerance) is unpleasant but not life-threatening. The symptoms overlap, so self-diagnosis is unreliable.
Getting tested: home-testing kits based on IgG are not diagnostically valid. If you suspect an allergy, ask a GP for referral to an allergy clinic for skin-prick or specific-IgE testing and a supervised food challenge where appropriate.