What is a food allergy?

A food allergy is an abnormal response by your immune system to some protein in your food. The symptoms usually start within a few seconds or minutes after eating the allergic food item. The symptoms vary from person to person, and according to the type of allergic reaction. IgE-mediated food allergy is the most common type. The symptoms may include:

• Itching or funny sensation in the mouth
• A raised, red rash that itches
• Swelling of different parts of the body
• Difficulty swallowing
• Wheezing and difficulty breathing
• Vomiting or the feeling of vomiting
• Hay-fever symptoms like sneezing or itchy eyes

A dangerous reaction called anaphylaxis may happen in very rare cases. This occurs suddenly and deteriorates rapidly. The symptoms usually start with a swollen tongue and difficulty breathing. This is a medical emergency. If you notice someone reacting adversely to food quickly, reach out to the emergency department immediately.

What are the common food items that cause food allergy rash?

Please note that this is a list of food items that some people may be allergic to. It is in no way a list of food items to avoid unless you have shown an allergy to it. Allergens vary from person to person and food item to food item. However, if you see someone developing serious symptoms after consuming any of these food items, take it seriously and seek out help if symptoms are worsening.

1. Soya beans and products made from it - Soy protein allergy is extremely common in children. This can cause itching, rashes and raised reddish areas. 
2. Egg and products made from it - Usually in children below 16 years. Can cause stomach pain and itchy rashes
3. Peanuts and food made using it - One of the most common, yet most dangerous food allergies. People can develop shortness of breath and excessive itching.
4. Cow’s milk and products made from it - Whey and casein are important proteins in cow’s milk. This usually presents as tingling and itching around the mouth and swelling of the mouth
5. Wheat and wheat products - Proteins like globulin, gluten, albumin and gliadin present in wheat cause reactions in about 1% of people
6. Shellfish and its preparations - Protein called tropomyosin can cause itching, hives and skin rashes
7. Nuts like almonds, pecans, walnuts, cashews, pistachios, hazelnut and brazil nuts - are very common affecting about 5% of the population. They can cause itching, swelling and rashes
8. Fish and fish products - Allergic reactions are usually against parvalbumin proteins present in them. This can lead to itching, congestion or stomach ache
9. Meat and meat products -  Usually the allergy is to red meat sources with symptoms like indigestion, stomach pain, and congestion.
10. Raw fruits and vegetables -  Fruits and vegetables have some allergic proteins which do not denature and break down when they are consumed raw.
11. Histamine-containing food - Wine, fermented food, dry fruit, cheese etc
12. Sulfite additives or naturally present sulfites in aged cheese and grapes
13. Gluten-containing food items