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Allergies Blood Test

Allergies are to blame for the body's response to substances that it is hypersensitive to. They may be usually harmless domestic products, foods, medicines, and/or inhalants. However, they are serious and should be treated with caution and appropriate action.

Allergies vary and lead to an inflammatory reaction: i.e. drug allergies cause itchy skin, hives, rashes, wheezing, and facial swelling and in severe cases anaphylaxis. Food allergies, in addition to the above, can also cause diarrhoea, abdominal pain, headache and nausea. Other identified allergens include inhalants which can aggravate an existing condition like asthma and cause severe respiratory problems which can only be dealt with in hospital and need prompt immediate action.

Insect stings and foods can trigger anaphylaxis, a life-threatening condition that can cause the body to go into shock. Symptoms of anaphylaxis include a sudden drop in blood pressure, light-headedness, a rapid and weak pulse, severe shortness of breath, a skin rash, vomiting and nausea and loss of consciousness. You may not recognise the onset of your symptoms and the cause. However, when they progress, as symptoms may not be immediate, and continue to get worse it becomes more apparent you have a problem and need to seek immediate help.


Same day appointments, as much time as you need with the doctor and instant referrals to our network of Consultant Specialists.

If you are experiencing health concerns, you don't have to wait any longer.

Your doctor will discuss testing and treatment options with you. Allergy testing is done by collecting a sample of your blood. The sample is sent to a laboratory for full analysis.

How to Prepare for the Test

Prior to the test please remember to drink plenty of water as it helps make it easier to draw blood. Allergy testing involves inserting a needle into a vein and drawing a small amount of blood. The site is usually on the inner arm.


You can discuss your symptoms and concerns with our GP. Based on the discussion, our doctor will recommend the most appropriate test. He/she will call you to explain the test results as well as follow up on the management of your condition. A further consultation with our doctor can be arranged to discuss and explain the implications and make sure you understand what this means for you. Or you can take the test results to your own GP.

How to Identify if You Have a Sensitivity or Allergy

There is a difference between sensitivity and an allergy. You may not have an allergy, but you may be sensitive to certain foods. Following an elimination diet by keeping a strict diary of what you eat over a period of a few weeks, together with any reactions that follow: i.e. diarrhoea abdominal discomfort, blurred vision, asthmatic type symptoms etc. Our doctor will then have a good idea of the leading cause, if it is food orientated, and check your diary with the accompanying symptoms. Hypersensitivity to certain foods and allergens is difficult to diagnose as the body is subjected to all types of chemicals daily and it may take a while to get it right. There are two types of allergens one is short acting. Your reaction will be immediate. The other is longer acting and only occurs up to three days after exposure to the allergen. You may not believe you are allergic initially however your diary will help determine if this is the case.

Causes of an Allergic Reaction

An allergic reaction is the inflammatory response of the immune system to an allergen. Different allergens can trigger an allergic reaction such as chemicals, dust, foods, pollen, medications and pet dander. Some people develop more allergies than others due to hereditary and genetic factors and living in an area or urban environment with high pollution. Some allergies are chronic, while others come and go.

When to Visit a Doctor

If you think that your symptoms are due to an allergic reaction and you are not getting any relief from OTC allergy medications, you should visit a doctor. If your symptoms start right after starting a new medicine, you should contact the doctor who prescribed it. If you or a family member is experiencing a severe allergic reaction, you should seek emergency medical help dial 999 or 112 straightaway especially if you are having breathing problems or in respiratory distress.


Same day appointments, as much time as you need with the doctor and instant referrals to our network of Consultant Specialists.

If you are experiencing health concerns, you don't have to wait any longer.

If you know what the allergy is, and have an auto-injector (for example EpiPen®, JEXT® or Emerade). This is a pre-filled injection device, containing adrenaline/epinephrine, it helps reduce the body's allergic reaction. However, you should still visit the emergency department in your area to make sure your symptoms do not return once the injection's effect wears off. It is important to see a doctor if you have had symptoms of anaphylaxis or a severe allergy attack before. Diagnosis, long-term management, and evaluation of anaphylaxis are complex, and an appointment with a doctor who specializes in immunology and allergies can be arranged from our clinic.



Suite 2, 117a Harley Street, London W1G 6AT


020 70968853

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Monday - Friday 9:00 - 21:00

Saturday - Sunday 10:00 - 14:00

About Us

At Walk in Clinic, we provide convenient and affordable private gp services to patients. If you are staying, visiting or working in London, then our gp appointments can be conducted in person by walking in at the clinic.