Immunology - Patients undergoing Allergy Challenges

Introduction

You have been referred for investigation of a suspected allergy. As part of this investigation, you have been offered an oral or injection challenge under supervision. An injection challenge is usually used to test for allergy to local anaesthetic, intravenous antibiotics or vaccines.

This will be done in the hospital on a day unit. It involves giving you small increasing doses of the substance suspected to have caused your allergic reaction. You will be closely monitored for any reactions.

If at any point you start to develop an allergic reaction, the challenge will be stopped. You may then be given treatment if required; this is dependent on the severity of the reaction.

How long will this take?

The challenge procedure may take a few hours to complete.

It is advisable to bring something to read or some entertainment to occupy yourself. You may bring your own food and drink to the day unit should you wish to.

What do I need to do before the challenge?

If you have a suspected food or drink allergy, we may ask you to bring in your own food preparation. If this is the case, you will be contacted to confirm this.

Medications

If you are taking regular antihistamines, you should stop taking them 3 days before your appointment.

Some medications (such as antihistamines and/or steroids) may hide a potential reaction if they are still in your system when we do the allergy challenge.

Inform a member of the Immunology team if you are taking beta blockers (e.g. atenolol), steroids, feel unwell, have an urticarial (hives) rash or if you have asthma and have been using your blue inhaler more frequently.

Avoid aspirin or similar non-steroidal anti-inflammatory drugs on the day of the allergy challenge.

Please speak to the Specialist Nurse prior to coming in if you have any concerns regarding your medication.

Eat and drink normally prior to the challenge.

On the day of the challenge

After you arrive on the unit, one of our Specialist Nurses will bring you in and prepare you for your allergy challenge.

They will take baseline readings of your blood pressure, temperature, oxygen levels and peak flow before starting the allergy challenge.

We may insert a very small, flexible tube into one of your veins, usually in the back of your hand or in your arm (cannula). This is precautionary in the event of a reaction during the challenge and enables us to give appropriate medication.
 
As part of the tests, we will sometimes need to carry out skin testing. If we need to do a skin test, we will discuss this with you beforehand.

Consent

Before we start any procedure, we will explain the risks and benefits and then ask you to sign a consent form.

If you are unsure of any part of the procedure the members of the team will be happy to discuss this with you in more depth before we proceed. Once you are happy and have signed the consent form the allergy challenge can begin.

What kind of reaction may I have?

The most common reactions are:

• Flushing or rash
• Itching
• Lip and facial swelling

Less common reactions are:

• Wheezing
• Itchy watery eyes and nose
• Nausea
• Rarely more severe reactions may occur including drop in blood pressure or anaphylaxis (severe life-threatening reaction)

After the challenge

We will keep you in hospital for observation following your last allergen dose.

If you experience a rare, delayed reaction after leaving the hospital you can take oral antihistamines. Please contact the Clinical Specialist Nurses on the number below for mild to moderate reactions.

Please seek urgent medical attention for more severe reactions such as difficulty in breathing, throat swelling and/or if you are feeling dizzy and unwell.

A discharge summary will be sent to your GP following the allergy challenge.

Contact details

Immunology/Allergy Clinical Nurse Specialists on 0161 206 5576 (8am to 4pm excluding bank and public holidays) or you can email us at salfordimmunology.nurses@nca.nhs.uk