Peanut allergy
Peanut allergy is common and can be severe, sometimes causing anaphylaxis.
About peanut allergy
Peanut is a legume rather than a true tree nut, but it is one of the most significant food allergens and a leading cause of severe allergic reactions in the UK. Allergy usually begins in early childhood and, unlike milk or egg allergy, is often lifelong, with only around a fifth of children outgrowing it. Reactions are IgE-mediated: the immune system produces antibodies to peanut proteins such as Ara h 2, and on later exposure these trigger mast cells to release histamine and other chemicals almost immediately.
Symptoms typically appear within minutes and can include an itchy mouth, hives, facial swelling, vomiting, wheeze and, in the most serious cases, anaphylaxis with breathing difficulty or a drop in blood pressure. Even trace amounts can provoke a reaction in highly sensitive people. Because peanut and tree nuts often appear together in foods, many people are advised to avoid both, though they are not botanically related.
Diagnosis is confirmed with skin-prick or specific-IgE blood tests and sometimes a supervised food challenge. Management centres on strict avoidance, careful label-reading and recognising traces in sauces, baked goods and Asian dishes. Those at risk of anaphylaxis carry an adrenaline auto-injector. A severe reaction is a medical emergency: use the injector and call 999 immediately.
Common triggers
- Peanuts and peanut butter\nSatay and many Asian dishes\nBaked goods and cereals\nSome sauces and sweets
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.