Tomato allergy
Tomato allergy or intolerance.
About tomato allergy
Tomato is a fruit in the nightshade family that can cause both true allergy and non-allergic intolerance, so symptoms are quite varied. Genuine allergy is IgE-mediated, with the immune system producing antibodies to tomato proteins, including a profilin and a lipid transfer protein, that trigger histamine release. Many people, however, react to natural substances in tomato such as histamine and salicylates, which can produce symptoms without an underlying allergy.
Symptoms usually appear within minutes to two hours and may include an itchy or tingling mouth, hives, a rash or flare of eczema around the mouth, swelling, stomach upset and, less commonly, wheeze or a wider reaction. In people sensitised through grass or birch pollen, tomato can cause oral allergy syndrome with mainly mouth symptoms, while lipid transfer protein sensitivity, more frequent in southern Europe, can occasionally lead to stronger reactions. Cooked tomato in sauces is tolerated by some but not all.
Diagnosis draws on the history supported by skin-prick or specific-IgE testing, with component testing sometimes clarifying the pattern, since intolerance and allergy are managed differently. Management means avoiding tomato in the forms that cause symptoms and checking sauces, soups and ready meals. Mild reactions often need only avoidance, but throat swelling or breathing difficulty is a medical emergency requiring 999.
Common triggers
- Tomato 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.