Allergy Testing

(Paediatric service only)

An allergy is an immune system response to something what is usually regarded as harmless. Foreign substances that trigger allergies are known as allergens and can include pollen, mould, certain foods, pet dander (dead skin cells) and things that can irritate your skin.


Causes of Allergies

The immune system is designed to keep the body healthy by fighting harmful pathogens. It achieves this by attacking anything it thinks could harm your body. It is not entirely clear why the immune system causes an allergic reaction when a typically harmless foreign substance enters the body. However, allergies have been found to have a genetic component, which means parents can pass them down to their children, although this is usually not the case for specific allergies such as food substances. Typical causes of allergies include:



Common foods that are known to cause allergies include wheat (gluten), nuts (commonly almonds, peanuts, cashews and walnuts), citrus fruit, milk, eggs and shellfish.


Insect Stings

Bees, wasps and mosquitoes often cause allergic reactions.


Pet Allergies

Household pets, even those that do not shed hair can provoke allergy symptoms. Contrary to what people think, it is not actually the pet that causes the allergy, but its dander, saliva, urine and fur. If you find yourself wheezing or sneezing after holding a pet, it is worth considering testing for animal allergies.



Airborne spores from mould can trigger an allergic reaction.


Plants (Hay fever)

Pollens from weeds, grass and trees, as well as resin from plants such as poison ivy and poison oak are very common plant allergens.



Common drugs known to cause allergic reactions include penicillin and sulfa drugs.


Other Allergens

Other substances that are known to cause common allergens latex which are found in latex gloves and condoms, and metals like nickel.


Food allergies are becoming more common, with the food groups making up approximately 90% of allergies.

Symptoms of Allergies

Allergies can cause a variety of symptoms that range from minor to life threatening. Common symptoms include:


  • Nasal congestion
  • Itching and watery eyes
  • Hives (an itchy rash)
  • Scratching or sore throat
  • Throat clearing
  • Sneezing
  • Stuffy or runny nose


A serious condition is anaphylaxis which is a severe reaction that can be life threatening. It affects the whole body and can come on very suddenly. Symptoms include:


  • Wheezing or shortness of breath
  • Hives and itching all over the body
  • Tingling in the hands, feet, lips or scalp
  • Swelling of the tongue and mouth
  • Hoarseness or tightness in the throat due to narrowed airways
  • Increased heart rate


Anaphylaxis is commonly caused by certain food (particularly peanuts), medications and insect bites/stings. Latex has also been known to bring on an anaphylactic reaction. If you believe you are going into anaphylactic shock, or someone close to you is, call 999 immediately. If an epinephrine shot is available, use is immediately and repeat after 5-15 minutes. Even if symptoms improve, you will still require medical attention as a delayed reaction could still happen.


Diagnosing Allergies

Diagnosing allergies can be carried out in a number of ways. Your doctor will take a detailed history of your symptoms and will likely perform a physical examination. They will discuss if you have done anything different recently such as eating a certain food or come into contact with something which could potentially cause an allergic reaction.


The most common way to test for allergies is through blood tests and skin tests.


Skin Test

A skin test will give the fastest, most accurate result. Also known as a scratch test, the doctor will prick your skin or make a small scratch on the surface to let the allergens get underneath it. You may feel a little discomfort, although it will not hurt. The doctor will test for several allergens at the same time to determine what is causing the reaction. If one of the areas swells up and becomes inflamed, it means you are likely to have an allergy to that particular substance.


Once the test is complete, your skin will be cleaned and cream added to alleviate any itching. Any reaction usually disappears within 30 minutes to a few hours.


Blood Test

If you have sensitive skin, have had a bad reaction to a skin test or are taking medication that could affect allergy test results, you doctor will take a blood sample instead. This is sent to a laboratory and the results will be available in a few days.


Other tests include:


Patch Testing

An allergen patch is applied to your skin for 48 hours. If your skin becomes irritated, itches or turns red, it is likely that you have an allergen to that particular substance.


Food Allergy Testing

To test for food allergies, your doctor will ask you to stop eating a particular food, usually for 2-4 weeks to determine if it causing your allergic reaction. If you do not have a reaction then you will be able to reintroduce the food back into your diet. This form of testing is called an elimination diet.


Treatment for Allergies

The best way to limit your allergies is to stay away from substances that trigger them, although for some this is not always possible. Depending on the severity of the allergy, it can often be treated with over the counter or prescription medication. Lifestyle changes will also help reduce the symptoms of allergies and avoid future triggers.  Allergy medications include:


  • Loratadine
  • Antihistamines
  • Corticosteriods
  • Decongestants
  • Cetirizine


Immunotherapy is a popular treatment for allergies. It involves a number of injections administered over the course of a few years to help the body get used to the allergy. If immunotherapy is successful, it can prevent allergy symptoms from returning.


If you are considering taking a natural remedy, discuss this with your doctor first as some supplements actually contain other allergens that can make your symptoms worse. Certain essential oils contain ingredients that can cause allergies, along with some dried teas that use flowers and plants that can cause severe sneezing.

Allergies and Babies

Skin allergies are becoming more common in younger children compared to a few decades ago. However, children tend to grow out of allergies as they grow up, although certain respiratory and food allergies can become worse as they grow older.


A number of skin allergies are common in babies; these include:



These are usually seen as raised areas of skin or red bumps. They do not become scaly or crack, but continued itching can cause them to bleed.



This is an inflammatory skin condition that can cause an itchy red rash. Eczema can develop slowly but be persistent over an extended period of time.


Contact Dermatitis

This type of skin allergy can appear very quickly, resulting in painful blisters and skin cracking. It is often caused when a baby comes into contact with an irritant.


Complications with Allergies

Allergy symptoms can create many complications, particularly if they result in anaphylactic shock. Once the cause of your symptoms has been determined, your doctor can teach you how to manage your allergy symptoms in order to avoid complications.


Need Help?

At One Healthcare we can book you in to see a specialist Paediatrician or Dermatologist, usually within 48 hours, for an initial consultation.  Treatment for allergies is available at One Ashford Hospital in Kent and One Hatfield Hospital in Hertfordshire.


Why One Healthcare

  • Modern purpose-built hospital opened in March 2016 (Ashford) December 2017 (Hatfield)
  • Fast access to diagnostics including MRI, X-ray and Ultrasound
  • Private, spacious, en-suite rooms
  • Specialist Physiotherapy and nursing teams
  • Little or no waiting time
  • ‘Ultra clean air’ theatres
  • Freshly prepared food
  • Calm, dignified experience

Contact us and find out more

If you live in and around the Kent area and would like to visit our One Ashford Hospital please click here

If you are based in and around Hertfordshire and would like to visit the One Hatfield Hospital please click here.

Contact the Hospital About Allergy Testing
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Choose a Hospital

One Ashford

01233 423 000

One Ashford, Kennington Road, Willesborough, Ashford, Kent, TN24 0YS

One Ashford Hospital
One Hatfield

01707 443 459

One Hatfield Hospital, Hatfield Ave, Hatfield, AL10 9UA

One Hatfield Hospital