Cashew allergy
Tree-nut allergy to cashews, sometimes severe.
About cashew allergy
Cashews are tree nuts related to pistachio and, more distantly, to mango, and they are one of the tree nuts that must be declared on UK food labels. Cashew allergy is common among tree-nut allergies and often persists throughout life. It is an IgE-mediated immediate allergy, in which the immune system makes antibodies to cashew storage proteins and later exposure triggers a rapid release of histamine and other chemicals.
Cashew is recognised as one of the tree nuts more likely to cause serious reactions, sometimes with only small amounts. Symptoms usually begin within minutes of eating and can include an itchy mouth, hives, facial swelling, vomiting, wheezing and, at the severe end, anaphylaxis with breathing difficulty or collapse. There is a strong cross-reactivity between cashew and pistachio, because the two nuts are closely related, so people allergic to one are often advised to avoid the other. Cross-reaction with other tree nuts is also possible.
Diagnosis is confirmed by an allergy specialist using skin-prick tests or specific-IgE blood tests, with component testing and sometimes a supervised food challenge to clarify the risk. Management centres on strict avoidance and careful label-reading, with attention to curries, pesto, cakes, nut butters and Asian dishes where cashew is common. Anyone at risk of anaphylaxis is usually prescribed an adrenaline auto-injector. A severe reaction is a medical emergency: use the auto-injector and call 999 immediately.
Common triggers
- Cashew 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.