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Allergy information for patients

Diagnosis and treatment of allergies 

Coronavirus: allergy update

In response to the coronavirus (COVID-19) outbreak, please read our advice and information before attending the service.

Appointment information

This  page provides information about your appointment with our allergy service.

  • How do patients get referred?

    Referrals come from GPs or from inpatient referral. All GP referrals must be submitted using the NHS e-Referral service (e-RS).

  • Cancelling or changing your appointment

    For a specialist allergy clinic, such as immunotherapy, food and drug allergy and challenges, please contact our appointments co-ordinator on 020 7188 5843.

    For general allergy appointments (including the contact allergy/patch testing clinic and omalizumab/urticaria clinic, please call:

    • 020 7188 8884 for new appointments
    • 020 7188 5833/020 7188 5846 for follow-up appointments.
  • Before your appointment

    You can eat and drink as normal before your appointment.

    If you are taking anti-histamine tablets, please stop taking these five days before your appointment as they may interfere with the tests. If, however, you need to take this medication, please contact us as we may need to reschedule your appointment.

    If you think you may be allergic to fresh foods, please bring along small samples for testing.

  • What to expect at your appointment

    You will be seen either by one of the consultant allergists, specialist registrars or clinical nurse specialists. They will talk to you regarding the signs and symptoms of the reaction that occurred, and what you think caused it.

    If you can, it's a good idea to bring a list of medications you are taking with you to the appointment. Similarly with the food allergy clinic, try to bring a sample of the food with you so that we can test you with this.

    You may then have a skin prick test to determine if an allergen is present. The results from this simple test are ready within 15 minutes. Depending on the results, some blood tests may then be taken and you may be invited to take a challenge/provocation test at a later date.

    Drug challenges

    This involves giving the drug by one of the following routes:

    • oral (by mouth)
    • subcutaneous (injection just below your skin)
    • intramuscular (injection into the muscle of your arm) 
    • intravenous (injection into your vein).

    The choice of route depends on the drug being tested, but the oral route is preferred whenever possible.

    We start by giving you a very small dose of the drug being tested by one of the routes above; this may be a diluted sample of the drug to be given intravenously or a small fraction of a tablet or syrup to be given orally. We will progress by giving you gradually increasing doses of the drug being tested at intervals of 15 to 60 minutes. Some medications will have longer interval times. Ask the doctor or nurse for more details.

    After the final dose has been administered, you will need to wait another one to two hours for further observation.

    It's important to remember to stop taking anti–histamine tablets five days prior to your drug challenge appointment.

    You should let the nurse or doctor know if you are taking beta blockers as these also need to be stopped the day before the test

    Food challenges

    This involves controlled exposure to a food under direct medical supervision and may be done to confirm if you are allergic or not to a food. This is often done if there is uncertainty after other tests have been performed. Sometimes challenges are performed to see if a patient has grown out of a food allergy.

    Food is almost always given in gradually increasing doses. The first exposure may involve just touching the food on the lip. Interval times between doses vary according to the food being tested. After the final dose is administered, you will need to wait a further hour in case of a delayed reaction.

    Please bring along the food for the challenge to the appointment. If you are in any doubt about what to bring, please contact the allergy team on 020 7188 5830.

    If you have any questions or concerns about your allergy challenge test please contact the allergy nurse specialist by calling 020 7188 5830 between 9am and 5pm at least five working days before your appointment. The messages are checked regularly and your call will be returned as soon as possible. Please leave your name and telephone number.

  • After your appointment

    A letter will be sent to you and your GP detailing all the tests and results.

  • Support groups and useful links

    • Allergy UK is the leading national charity dedicated to supporting the estimated 21 million allergy sufferers in the UK. They provide a dedicated helpline, support network and online forum for those with allergy and intolerance. Allergy Helpline: 01322 619898.
    • UK Anaphylaxis Campaign provides information and support relating to foods and other triggers such as latex, drugs and insect stings.
      Tel 1252 542 029.
    • Medic Alert supplies identification system for individuals with hidden medical conditions and allergies. Tel: 0800 581 420.
    • EpiPen (order trainer device) provides a service for patients who have been prescribed an EpiPen auto injector. Trainer pens and a service to remind you when your pen needs replacing are available on request. Tel 01488 686 016. 
    • HAE UK aims to answer some of your questions about Hereditary Angioedema, an inherited condition also known as HAE. Contact Ann Price (tel: 07975 611787), HAE UK Patient Support, to discuss your HAE needs in confidence, or write to HAE UK, PO Box 448, Bridgwater, TA6 9GB.



Tel: 020 7188 5846 or 020 7188 7263

Email: gst-tr.allergyadult