Food allergy happens when the immune system reacts to a food that is normally harmless. Reactions usually start within minutes to two hours of eating, and range from an itchy mouth or rash to swelling and, rarely, a severe reaction called anaphylaxis.
Finding the cause, or ruling out allergy, helps you avoid unnecessary restrictions and know what to do if a reaction happens.
If you have swelling of the tongue or throat, difficulty breathing or swallowing, or feel faint, call 999 straight away.
Allergy Clinic
Dr John Reed is a consultant dermatologist with a specialist interest in urticaria, angioedema and allergy. His allergy consultation is longer than a standard appointment, so there is time to go through your reactions in detail.
Where it will help, he can arrange skin prick testing and blood tests at Derma.
Symptoms of Food Allergy
Signs of an allergic reaction to food can include:
- itching or tingling of the mouth, lips or throat
- hives (raised, itchy wheals) or flushing of the skin
- swelling of the lips, face or eyes (angioedema)
- tummy pain, vomiting or diarrhoea
- sneezing, wheeze or a cough
A severe reaction (anaphylaxis) can cause throat swelling, difficulty breathing, a drop in blood pressure and collapse. It needs emergency treatment with adrenaline.
Causes of Food Allergy
Almost any food can cause an allergy, but the most common triggers in adults are peanuts, tree nuts, fish, shellfish, sesame, milk and egg. In children, milk, egg and peanut are the most common.
Some people with hay fever get an itchy mouth after eating raw fruit, vegetables or nuts. This is called oral allergy syndrome (pollen food syndrome). It is usually mild, and cooked versions of the same foods are often fine.
Food intolerance is different. It does not involve the immune system, does not cause anaphylaxis, and cannot be detected by allergy tests.
Diagnosis of Food Allergy
The most important part of the diagnosis is a detailed history: which foods you ate, how quickly symptoms started, what they were and how long they lasted.
Depending on your history, Dr Reed may recommend skin prick testing or allergy blood tests. Tests are only useful when they are chosen to match your history; broad panels of food tests often give misleading results.
Treatment at Derma for Food Allergy
Treatment depends on what is found. It may include:
- avoiding a confirmed food trigger, with practical advice on reading labels and eating out
- reassurance and reintroducing foods that are not causing a problem
- antihistamines for mild reactions
- a written allergy action plan, and adrenaline auto-injectors with training if you are at risk of anaphylaxis
- referral to a specialist allergy service where needed
Frequently Asked Questions
When should I call 999?
Call 999 if you have swelling of the tongue or throat, difficulty breathing or swallowing, or feel faint or dizzy. These can be signs of anaphylaxis.
Can allergy tests diagnose food intolerance?
No. Skin prick and blood tests look for allergy. They cannot diagnose intolerance, and commercial “intolerance” tests are not recommended.
Can food allergies be outgrown?
Children often outgrow milk and egg allergy. Peanut, tree nut, fish and shellfish allergies are more likely to continue into adulthood.
Related Specialists at Derma
Dr John Reed
Consultant Dermatologist
General dermatologySkin surgery
Specialist interest in urticaria, angioedema and allergy.