FAQs: Anaphylaxis

This page contains answers to your frequently asked questions on anaphylaxis.

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This page was last updated in October 2021.

These questions relate to anaphylaxis treatment. To view the answers, click the question or the + sign next to the question.


This guidance is for individuals who are expected to recognise and treat anaphylaxis as part of their usual clinical role. Healthcare providers include a wide range of clinicians who may have to treat anaphylaxis as part of their clinical role (e.g. doctors, nurses, dentists, ambulance paramedics, radiographers, etc). 

The Medical and Health Care Products Regulatory Agency (MHRA) has provided the following advice for health care professionals (15 August 2017):  

  • It is recommended that 2 adrenaline auto-injectors are prescribed, which patients should carry at all times 
  • Ensure that people with allergies and their carers have been trained to use the particular auto-injector that they have been prescribed - technique varies between auto-injectors 
  • Encourage people with allergies and their carers to obtain and practice using a trainer device  

In addition, the MHRA states that patients should be advised to ‘check the expiry date of the adrenaline auto-injectors and obtain replacements before they expire; expired injectors will be less effective’. 

Auto-injectors are primarily for self-use by patients in case of anaphylaxis, and should be prescribed on an individual patient basis. These guidelines are aimed at healthcare providers in a variety of settings. We have not specifically recommended auto-injectors for use by this group for several reasons: 

  • Auto-injectors are relatively expensive with a limited shelf life compared with the cost of an ampoule of adrenaline and syringe and needle. Anaphylaxis is uncommon. Most auto-injectors purchased for the healthcare setting will not be used. 
  • The recommended dose of adrenaline in teenagers and adults is 500 micrograms, however most auto-injectors prescribed for adults deliver a 300 microgram dose. 
  • Auto-injectors come with standard length needle which may not be long enough to give intramuscular (IM) adrenaline for some patients. 
  • Most healthcare providers likely to deal with anaphylaxis in the healthcare setting should have the skills to draw up adrenaline and give an intramuscular injection of adrenaline. 

Ultimately it is a local decision whether a healthcare setting opts to use auto-injectors instead of adrenaline ampoules. If there is no other form of adrenaline available, it would be appropriate for a healthcare professional to use an adrenaline auto-injector for the treatment of anaphylaxis. If a second dose of adrenaline is required it should be given with syringe and ampoule if possible in order to give an appropriate dose with an appropriate needle length. However, if no ampoule and syringe is available a second auto-injector can be used.

Some settings (e.g. allergy challenge clinics) may recommend a patient to self-administer adrenaline using an auto-injector under supervision, to train them in its use, which is associated with significant patient benefit. 

All patients with a suspected or proven anaphylaxis should be offered the opportunity to be reviewed in an allergy clinic. Emergency departments should identify their nearest allergy clinic to ensure that there is local guidance in place for the further care of these patients. Issues that will need to be addressed in follow-up include:

  • confirmation of the diagnosis
  • investigation of possible causes of anaphylaxis
  • advice on future prevention strategies including advice on emergency management
  • education for the patient.

The British Society for Allergy and Clinical Immunology (BSACI) website shows locations and contact details for allergy clinics. 

In the rare circumstances that an auto-injector is considered to be necessary, it would be appropriate to prescribe and recommend for use one containing 150 micrograms adrenaline. This should only be prescribed by a paediatric allergy specialist. 

The law does not prevent a healthcare practitioner treating anaphylaxis by administering an adrenaline injection that:  

  • either has been prescribed to a specific person (e.g. an adrenaline auto-injector)  
  • or is from an emergency drug supply, for example, a dedicated emergency trolley or bag.  

Adrenaline is a prescription-only medicine (POM). Under Regulation 214 of The Human Medicines Regulations 2012 (which can be found at www.legislation.gov.uk), “a person may not parenterally administer (otherwise than to himself or herself) a prescription-only medicine unless the person is “an appropriate practitioner” (e.g. doctor, dentist, nurse prescriber) or acting in accordance with the directions of such a practitioner.  

However, a number of medicines are exempt from this restriction, where “this is for the purpose of saving life in an emergency” (Regulation 238). This includes adrenaline.  

Where adrenaline is held as an emergency drug (and not specifically provided on a named-patient basis), any person competent to do so may administer adrenaline (using 1 mg/mL strength) at the doses recommended in this guideline, without the need for it to be prescribed first. However, the individual must be working within the standards of the relevant regulator (e.g. Nursing and Midwifery Council; Health and Care Professionals Council) or other supervisory body and competent in being able to recognise anaphylaxis and administer adrenaline, either from an ampoule by syringe and needle or an auto-injector device that has not been prescribed on an individual-patient basis. 

Where the adrenaline has been prescribed for a named person (e.g. as an auto-injector), the auto-injector can be administered by any person competent to do so, but only to the person for whom the auto-injector has been prescribed. Currently, the law does not allow a non-prescriber to administer an adrenaline auto-injector, which has been specifically prescribed for a named person to someone other than the person for whom it has been prescribed.  

Where the adrenaline auto-injector has been prescribed for a named person, the auto-injector can be administered by any person competent to do so, but only to the person for whom the auto-injector has been prescribed. The first aider involved must be competent in being able to recognise anaphylaxis and administer adrenaline using an auto-injector. First aiders must ensure that they work within the guidelines of the first aid training organisation that issued their qualification, and their employer. 

Currently, the law does not allow a non-prescriber to administer an adrenaline auto-injector, which has been specifically prescribed for a named person to someone other than the person for whom it has been prescribed. Under Schedule 17 of the Human Medicines Regulation (as amended in 2017), “generic” adrenaline auto-injectors can now be supplied to schools without being issued against a prescription. The legislation allows for any person who is “carrying on the business of a school” and who is suitably trained to do so, to administer such an auto-injector for the emergency treatment of anaphylaxis. Further information can be found at sparepensinschools.uk.  

No, you should only give IV adrenaline if the patient is in cardiac arrest. The IM route for adrenaline is the route of choice for the vast majority of healthcare providers. IV adrenaline should only be given by experienced specialists in an appropriate setting.  

There is a fundamental difference in the response to adrenaline when given to a patient with a spontaneous circulation compared with when it is given in cardiac arrest. In the patient with a spontaneous circulation, intravenous adrenaline can cause excessive hypertension, tachycardia and arrhythmias – this is why this route should be used only by someone with experience in titrating adrenaline to produce an appropriate haemodynamic response. In cardiac arrest, intravenous adrenaline is given to increase the coronary perfusion pressure achieved during CPR – under these circumstances absorption from an intramuscular injection would be too unreliable. 

Once cardiac arrest occurs it is important to ensure expert help is coming and start cardiopulmonary resuscitation (CPR) immediately. Good quality CPR with minimal interruption for other interventions improves the chances of survival from cardiac arrest. Once cardiac arrest has occurred, the absorption of adrenaline given by IM injection may not be reliable, therefore IM adrenaline is not likely to beneficial. Attempts to give IM adrenaline may also interrupt CPR. Advanced life support according to current guidelines should start as soon as possible. 

Allergic rashes alone are relatively common and usually respond to an oral dose of antihistamine (e.g. cetirizine). However, if the patient has, or is developing, problems with their Airway/Breathing/Circulation, then this is anaphylaxis and IM adrenaline should be administered as per the anaphylaxis algorithm. If in doubt, give IM adrenaline and monitor the response as outlined in the guideline. 

Auto-injectors are recommended primarily for use by members of the general public for self-administration. Guidance for their use must allow a greater degree of safety in terms of dose and recommended dosing interval. There is little science on which to base a recommendation for the dosing interval. The recommendation of 5 minutes is pragmatic and based on the personal experience of those who use adrenaline in their regular practice. Waiting for 10-15 minutes for a response before giving a further dose may be excessive in a patient with life-threatening airway, breathing or circulation problems caused by anaphylaxis. 

The IM doses we recommend are for healthcare providers who rarely deal with paediatric emergencies. The doses have been chosen because they are easy to draw up and administer and are within the safe acceptable dose ranges for the particular age groups. 

Specialists working in critical care settings may wish to administer more precise doses based on a patient’s weight. These guidelines do not preclude this. 

The Department of Health guidance on this issue does not state a specific time (see Green Book guidance) but does not recommend long periods of observation.

The risk of severe life-threatening reactions after immunisation is extremely small. This rate in the UK (about one per million vaccine doses) is similar to that reported from other countries (Bohlke K, Davis RL, Marcy SM, Braun MM, DeStefano F, Black SB, et al. Risk of anaphylaxis after vaccination of children and adolescents. Pediatrics 2003;112(4):815-20). The rate for COVID-19 vaccines for any severity of anaphylaxis is estimated as about 8 per million doses (Greenhawt M, eta al. The Risk of Allergic Reaction to SARS-CoV-2 Vaccines and Recommended Evaluation and Management: A Systematic Review, Meta-Analysis, GRADE Assessment, and International Consensus Approach. J Allergy Clin Immunol Pract. 2021 Oct;9(10):3546-3567. doi: 10.1016/j.jaip.2021.06.006. 

Based on the information available a short period of observation (5-15 minutes) should be used to detect immediate problems. Patients (and carers) should be provided with advice on possible local and systemic reactions and what to do if they occur. 

No, you don’t need to be carrying antihistamines and steroids. These drugs can be administered when the patient arrives in hospital. Adrenaline is the mainstay of treatment for an anaphylactic reaction. Steroids such as hydrocortisone are no longer recommended for the routine treatment of anaphylaxis. 

Antihistamines are not recommended for the treatment of Airway/Breathing/Circulation problems, in anaphylaxis. The key steps are using an ABCDE approach to recognise anaphylaxis, calling for help early and administering IM adrenaline. The risk of anaphylaxis after immunisations is very small. Considering these facts, it is not necessary to carry these drugs. 

It is important to make sure you can access a telephone easily to call an ambulance. 

Immunisation against infectious disease, The Green Book, Department of Health states [ https://www.gov.uk/government/collections/immunisation-against-infectious-disease-the-green-book accessed 26 October 2021] 

[Chapter 8, Vaccine safety and the management of adverse events following immunisation]: 

“An anaphylaxis pack normally contains two ampoules of adrenaline (epinephrine) 1:1000, four 23G needles and four graduated 1 ml syringes, and Laerdal or equivalent masks suitable for children and adults. Packs should be checked regularly to ensure the contents are within their expiry dates. Chlorphenamine (chlorpheniramine) and hydrocortisone are not first-line treatments and do not need to be included in the pack.”

Resuscitation Council UK has taken advice from several sources. A PGD is not required for anyone (whether they are a healthcare professional or not) to give intramuscular adrenaline for the purpose of saving a life in an emergency. 

The Statutory Instrument (SI) is 1997 The Prescription Only Medicines (Human Use) Order no 1830. It can be found on the website www.legislation.gov.uk (formerly at HMSO). This Statutory Instrument amends the main Statutory Instrument on prescribing which is the Medicines (Products other than veterinary drugs) (prescription only) order 1983 Statutory Instrument;

Article 7 of the 1997 SI states:

"The restriction imposed by s58 (2)(b) (restriction on administration) shall not apply to the administration to human beings of any of the following medicinal products for parenteral administration: Adrenaline injection 1 in 1000 (1 mg in 1mL), Atropine sulphate injection, Chlorpheniramine [chlorphenamine] injection, Cobalt edetate injection, Dextrose injection strong BPC, Diphenhydramine injection, Glucagon injection, Hydrocortisone injection, Mepyramine injection, Promethazine hydrochloride injection, Snake venom antiserum, Sodium nitrate injection, Sodium thiosulphate injection, Sterile pralidoxime. Where the administration is for the purpose of saving life in an emergency"

The impact of this article is that where parenteral administration is being used (this is defined as administration by breach of the skin or mucous membrane), and it is for an emergency to save life, then s.58(2)(b) does not apply. This section states that no administration shall take place unless it is by an appropriate practitioner or a person acting in accordance with the directions of an appropriate practitioner.

Also, the Medicines, Ethics and Practice guide for pharmacists and pharmacy technicians issued by the Royal Pharmaceutical Society of Great Britain (updated July 2007) states that intramuscular adrenaline injection (1 in 1000) is exempt from requiring a prescription when given for the purpose of saving a life in an emergency. This is also based on article 7 of the prescription-only medicines (POM) order.

This means that any nurse, teacher, parent, etc, can administer adrenaline (or any of the other named drugs) if the purpose is to save life, without needing permission from an authorised prescriber. If they do this, they will not commit an unlawful act under the Medicines Act 1968. 

Note, however, that this only applies to adrenaline which has not been prescribed on a named-person basis. Adrenaline which has been prescribed to a named individual, for example as an adrenaline auto-injector, can only be administered to that named individual under current legislation. Currently, the law does not allow a non-prescriber to administer an adrenaline auto-injector, which has been specifically prescribed for a named person to someone other than the person for whom it has been prescribed.

PGDs are only valid for the NHS, Defence Medical Services, police custody, independent sector clinics or hospitals.

Some organisations may still wish to have a PGD in place as a framework to guide local practice and training needs. This is their choice as they are the ones who are vicariously liable for their practitioners. It is important that trained staff are not put in the position that they feel they cannot give adrenaline for anaphylaxis because they think they are “not covered” for this.

Information about PGDs is available on the NICE website.

A standard blue needle (25mm and 23G) should be used to inject intramuscular adrenaline. In obese patients a longer green needle may be needed (38 mm length and 21G).

The best site for an intramuscular injection of adrenaline for the treatment of an anaphylactic reaction is the anterolateral aspect of the middle third of the thigh. The needle needs to be long enough to ensure that the adrenaline is injected into muscle. 

Anaphylaxis after immunisation is very rare. Based on a risk assessment oxygen would not be routinely needed by nurses to enable them to administer immunisations in the community. Nurses who administer immunisations should be able to access help from the ambulance service in an emergency.

The “Green Book” provides guidance on what is required for the “anaphylaxis pack”.

Immunisation against infectious disease. The Green Book 2006, Department of Health states [https://www.gov.uk/government/collections/immunisation-against-infectious-disease-the-green-book - accessed 26 October 2021]:

[Chapter 8, Vaccine safety and the management of adverse events following immunisation]: 

“An anaphylaxis pack normally contains two ampoules of adrenaline (epinephrine) 1:1000, four 23G needles and four graduated 1 ml syringes, and Laerdal or equivalent masks suitable for children and adults. Packs should be checked regularly to ensure the contents are within their expiry dates. Chlorphenamine (chlorpheniramine) and hydrocortisone are not first-line treatments and do not need to be included in the pack."

Individuals who require training to use an auto-injector include those who have to carry an auto-injector for self-use and those who may have to treat a person with anaphylaxis using an auto-injector e.g. parents, carers and teachers.

There is no statutory legal requirement in the UK deeming who is suitably trained to train others. However, any trainer has an obligation under common law to ensure they are competent to train others. Resuscitation Council UK recommends that those who train others in treating anaphylaxis and the use of adrenaline auto- injectors should be appropriately qualified.

Trainers should be skilled in teaching others and be able to demonstrate competency in teaching others how to recognise and treat anaphylaxis including the use of an adrenaline auto-injector. The following groups are suggested as trainers: doctors, nurses, resuscitation officers, registered paramedics, statutory ambulance service trainers, voluntary aid society and voluntary rescue organisation trainers, and other individuals such as accredited first aid trainers. This list is not exhaustive.

Whilst there is no prescriptive course programme, training for trainers should be based on current Resuscitation Council UK recommendations. Trainers should also be familiar with the current legislation which applies to their client group.

All those who prescribe adrenaline auto-injectors must ensure that individuals who carry an auto-injector receive training in its use. There is more than one available brand of auto-injector so training will need to be tailored accordingly.

Adrenaline auto-injectors are not intuitive and everyone who attends training needs to be shown how to use the device and also be given an opportunity to practice using a training device. Anaphylaxis training should also include avoidance of allergens, the early recognition of symptoms and crisis management which would include when to administer emergency treatment, and how to care for the patient whilst waiting for emergency services to arrive.