Adult allergy

Allergic diseases happen when the immune system overreacts to something in the environment, usually proteins, chemicals, or drugs. 

To say a reaction is truly allergic, three things must be true: 

1. It’s caused by something in the environment 
2. The immune system is involved
3. It causes symptoms or damage in the body 

The immune system is complicated, with different types of white blood cells, chemicals (called mediators), and proteins (called antibodies). 

Our service mainly deals with one kind of allergic reaction called Type 1 hypersensitivity. This involves: 

• White blood cells called T2 lymphocytes, eosinophils, and mast cells 
• Chemicals like histamine and leukotrienes (medicines that block histamine are often used to treat allergies) 
• A specific antibody type called IgE 

Other types of allergies involve different parts of the immune system. 
For example: 

• Contact allergic dermatitis (a skin allergy from chemicals) is treated by dermatologists 

• Coeliac disease (an allergy to gluten) is managed by gastroenterologists 

Some problems are often confused with allergies but aren’t caused by the immune system. For instance, lactose intolerance happens when the body lacks the enzyme to break down milk sugar. It’s not an allergy and can be diagnosed with a simple test by the gastroenterology department. 

Read more information about allergies (NHS England website)

The type of allergic symptoms someone gets depends on where the allergen (the trigger) enters the body: 

• Pollen particles are large and usually stay in the nose, eyes, and throat, causing hay fever (rhinitis), itchy eyes, or sneezing. 
• Smaller particles, like house dust mites or pet dander, can get into the lungs and trigger asthma. 
• Food allergens or allergens from insect stings or drugs, which are eaten or injected, can affect the whole body and may lead to a serious reaction called anaphylaxis. 

We diagnose and manage: 

• Asthma 
• Rhinitis (hay fever) 
• Food allergies 
• Anaphylaxis (severe allergic reaction) 
• Urticaria (hives) and Angioedema (swelling) – when caused by an allergy 

All of these can be linked to a Type 1 allergic response, which is caused by the immune system reacting too strongly and producing a specific antibody called IgE. 

To diagnose a Type 1 allergy, we usually look for IgE antibodies in the blood or on the skin: 

• Skin prick tests (SPT) are quick, safe, and done in clinic. 
• A blood test can also detect IgE antibodies to specific allergens. 

However, just having the antibody doesn’t always mean you’ll have symptoms. Some people make IgE antibodies but never react, we don’t yet fully understand why. 

So, it’s important to link: 

• The allergen (what you’ve been exposed to)
• With the symptoms (what happened in your body)
• And the test result (finding IgE antibodies)

If we can find the allergen causing your symptoms, avoiding it can be the best form of treatment, and in some cases, it can even lead to a cure.

• Allergic rhinitis (eg hayfever) – NHS 
• Anaphylaxis – NHS 
• Drug allergy – Allergy UK 
• Food allergy – NHS 
• Oral Allergy Syndrome (Pollen Food Syndrome) – Allergy UK 
• Latex Allergy – Anaphylaxis UK 
• Venom Allergy – Allergy UK 
• Urticaria and angioedema – British Association of Dermatologists 

Please find our UHL allergy patient information leaflets on YourHealth. 

More information can be found through the follow patient organisations:

• Allergy UK
• Anaphylaxis UK

We may see patients where symptoms are difficult to assess, and allergy is being considered as a cause. We require a detailed referral to ensure all such cases are appropriate for Allergy clinic review. Generally, our role is to confidently exclude allergy as a cause. 

Asthma is commonly caused by allergens such as house dust mite, allergens from furry animals, pollens or fungal spores. Patients whom asthma is the key concern usually benefit from Respiratory review in the first instance. Many patients with asthma also have other allergies and attend the Allergy clinic for this reason. 

Food intolerance is not an allergic problem. It is a condition where people develop symptoms with certain foods but with no evidence that the immune system is involved. Patients in whom food intolerance is the key concern usually benefit from Gastroenterology review in the first instance. 

We have no expertise in the diagnosis or management of Mast Cell Activation Syndrome (MCAS). MCAS patients may also have symptoms of a Type 1 hypersensitivity response and may be assessed for this.