Soya Allergy

Soya (soy) comes from the soya bean, a legume used in many foods like tofu, soy sauce and baked goods. Soya allergy is less common than milk, egg or peanut, but reactions do happen. This page gives a clear overview in the same format as our other guides.

Overview

Soya allergy can be immediate (IgE‑mediated) or delayed (non‑IgE). Immediate reactions usually happen within minutes; delayed reactions can take hours. Most reactions are mild, but severe symptoms (anaphylaxis) are possible in rare cases.

Symptoms

Rapid‑onset symptoms may include:

• Itchy, raised rash (hives)
• Tingling/itching in the mouth
• Swelling of lips, face or eyes
• Tummy pain, nausea or vomiting

Severe reaction (anaphylaxis) can involve:

• Airway: throat or tongue swelling, hoarse voice, trouble swallowing
• Breathing: wheeze, shortness of breath, noisy breathing
• Circulation: dizziness, faintness, pale clammy skin, confusion or collapse

Delayed reactions

Non‑IgE reactions usually affect the gut and develop more slowly (hours to days). Typical symptoms are tummy pain, diarrhoea, vomiting, reflux or colic. This type does not lead to anaphylaxis.

Diagnosis

If you suspect soya allergy, speak to your GP about a referral to an NHS allergy clinic (find via BSACI). Diagnosis may include medical history, skin‑prick or blood tests, and sometimes a supervised food challenge.

Who is at higher risk?

• A previous serious reaction
• Asthma, especially if not well controlled
• Reactions to very small amounts of soya

Treatment

Mild symptoms: an oral antihistamine may help. If you’re at risk of severe reactions, you should carry two prescribed adrenaline auto‑injectors and know how to use them. In an emergency, call 999.

Avoiding soya

• Read labels every time — soya is one of the UK’s 14 major allergens and must be highlighted in ingredients.
• Common sources: edamame, tofu/soya curd, soya flour (in breads/cakes), TVP/HVP (textured/hydrolysed vegetable protein), lecithin (E322), soy/soya sauce.
• Soya oil: fully refined oil is very unlikely to cause reactions; unrefined oil may still contain protein.
• Ask when eating out and consider cross‑contamination risks.

Other legumes & peanuts

Soya is a legume. Cross‑reactivity with other legumes (peas, beans, lentils) is uncommon, but discuss any reactions with your allergy team. Children with soya allergy may also have peanut allergy.

Useful links

• NHS — Food allergy
• Allergy UK
• BSACI — Find an allergy clinic