Allergists Dr Andrew Clark and Dr Shuaib Nasser offer tips on who needs one and advice to give patients
1. Any patient who has experienced symptoms of airway narrowing or cardiovascular compromise during a previous allergic reaction should be given an injectable adrenaline device.
Also, food-allergic patients who have asthma that requires inhaled steroids may benefit from one. They may also be given to patients with nut allergy who have only reacted to previous trace or cutaneous exposure, as their full sensitivity has never been tested.
2. It's equally important to know who doesn't need one.
Patients without asthma, who have only ever had mild reactions to ingestion of large amounts of allergen, don't. So most children with egg and milk allergy don't need one, as these allergies are usually mild and resolve within two or three years.
3. Providing good allergen avoidance advice is as important as providing an adrenaline injector.
Although there is much discussion about the provision of emergency medication, the main thrust of allergy care is to provide effective allergen avoidance advice.
4. Most patients only need to be prescribed one injector at a time.
But it is often convenient for children to have one at home and one at school. In exceptional circumstances, it may be justified to provide more than one to a patient – for instance, if more than one was needed during a previous reaction, if the patient has a large body mass index or if the patient will be a long way from emergency care.
5. There are important differences in the way various pens are activated.
There are two licensed devices: EpiPen and Anapen. Both are auto-injectors available with a single dose of either 0.15mg or 0.3mg of adrenaline for intramuscular injection – 0.15mg is the ‘junior' pen, for body weight between 15-30kg, and 0.3mg is the ‘adult' pen, for body weight over 30kg. Both are designed to inject through all types of clothing, but there are important differences in the way they are activated. They should be stored at room temperature.
6. Anyone with an adrenaline auto- injector should also carry oral antihistamines and use these first during any allergic reaction.
The injector should only be used after the antihistamine has been taken, if the patient suffers significant respiratory distress or cardiovascular symptoms. Stress to patients that they need to go to A&E if they've used the injector, as they may become ill again when the dose wears off.
7. It's important patients know what to do when they misfire a pen.
The most common mistake is to hold the pen upside down so the adrenaline is injected into the finger. This causes intense pain and pallor of the finger and risks ischaemia and tissue loss. Tell the patient to run the finger under warm water and keep an eye on it. If the circulation doesn't return in a reasonable time they should consult a doctor so it can be examined – with the possibility of a subcutaneous injection of phentolamine into the affected area.
8. All patients who have been given an injector should be referred to an allergy clinic.
These patients benefit from a comprehensive management plan – including allergen identification and detailed written and verbal allergen avoidance advice. Patients receive a printed emergency treatment plan which can be passed to a child's school or nursery. Allergy services will also advise when the devices are no longer required.
9. Patients might find it useful to get a trainer pen and practise at home.
All patients should be trained how to use their own device using dummy trainer pens, which are available from the manufacturers.
10. Demonstration videos are available online.
Patients can get advice and support from the Anaphylaxis Campaign (www.anaphylaxis.org.uk) or Allergy UK (www.allergyuk.org), which provides newsletters, a telephone helpline, translation cards and food warnings. A training video is available on the Anaphylaxis Campaign site. GPs can get advice from their local allergy clinic, the address of which can be found on the website of the British Society for Allergy and Clinical Immunology (www.bsaci.org).
Dr Andrew Clark is consultant in paediatric allergy
Dr Shuaib Nasser is consultant in allergy and asthma at Cambridge University Hospitals NHS Foundation Trust
Competing interests None declared
Child injecting adrenaline Adrenaline auto-injectors
