HelplineAnaphylaxis is one of the few medical emergencies in which early clinical judgement and decisive action can be immediately life-saving. It occurs across all healthcare settings, from general practice and community clinics to emergency departments and specialist allergy services and yet delays in recognition and treatment remain common. Too often, these delays arise not from lack of knowledge, but from uncertainty: uncertainty about diagnosis, uncertainty about severity, plus hesitation about when to act.
In the UK, hospital admissions for anaphylaxis have increased steadily over recent decades, particularly among children and young people. While this reflects improved awareness and reporting, preventable morbidity and mortality persist. Failure to recognise anaphylaxis promptly, or delay in administering adrenaline, continues to underpin the most serious outcomes.
Recent updates to national guidance have brought welcome clarity. Adrenaline is unequivocally the first-line treatment. Corticosteroids are no longer recommended for routine management. At the same time, the emergence of needle-free adrenaline delivery systems offers new opportunities to address real-world barriers to timely treatment, particularly in community settings.
This article reviews current best practice in the recognition, management and prevention of anaphylaxis, with a focus on practical decision-making for clinicians working across primary and secondary care. By reinforcing core principles and addressing recent developments, it aims to support confident, timely and evidence-based care when it matters most.
Defining Anaphylaxis
Anaphylaxis is defined as a serious, systemic hypersensitivity reaction that is rapid in onset and may be fatal. It is characterised by life-threatening compromise of the airway, breathing and/or circulation. Skin and mucosal symptoms are common but not universal and should not be relied upon to make or exclude the diagnosis.
Anaphylaxis is a clinical diagnosis. There is no diagnostic test that confirms anaphylaxis at the point of care, and treatment decisions must be based on clinical features rather than investigations. Management should never be delayed while awaiting laboratory results.
Pathophysiology
Most cases of anaphylaxis are IgE-mediated. Allergen exposure leads to cross-linking of allergen-specific IgE on mast cells and basophils, triggering rapid release of mediators including histamine, leukotrienes, prostaglandins, and platelet-activating factor. These mediators cause vasodilatation, increased vascular permeability, bronchoconstriction, mucous secretion and, in severe cases, cardiovascular collapse.
Non–IgE-mediated mechanisms can produce clinically indistinguishable reactions and should be managed in the same way.
Recognising Anaphylaxis
Clinical Features
Anaphylaxis typically involves symptoms affecting more than one organ system and may include:
Skin and mucosa
- Generalised urticaria
- Angioedema (lips, tongue, eyelids)
- Flushing or pruritus
Airway and breathing
- Throat tightness or hoarseness
- Stridor
- Wheeze
- Persistent cough
- Dyspnoea
Circulation
- Hypotension
- Tachycardia
- Dizziness, syncope or collapse
Gastrointestinal
- Abdominal pain
- Vomiting or diarrhoea.
Importantly, skin symptoms may be absent in up to 20% of cases, particularly in severe or rapidly progressive reactions. Their absence should not delay treatment.
Common Diagnostic Pitfalls
Misdiagnosis remains a significant contributor to delayed treatment. Wheeze may be attributed to asthma, gastrointestinal symptoms to food intolerance, or collapse to a vasovagal episode. Any sudden onset of airway, breathing, or circulatory compromise following possible allergen exposure should prompt immediate treatment for anaphylaxis.
Triggers of Anaphylaxis
Triggers vary by age and exposure but commonly include:
- Foods (for example, peanut, tree nuts, milk, egg, sesame, shellfish but also others)
- Insect venom
- Medications (particularly antibiotics and NSAIDs)
- Latex
- Exercise, including food-dependent exercise-induced anaphylaxis.
Additionally, in a significant minority of cases, no trigger is identified. (1)
Acute Management
Adrenaline: The first-line Treatment
Adrenaline is the only first-line treatment for anaphylaxis. It should be administered promptly at the first signs of airway, breathing or circulatory compromise. (2)
Intramuscular injection into the anterolateral thigh remains the gold-standard route. Repeat dosing is indicated after 5 minutes if symptoms persist or worsen. (3)
Delayed administration of adrenaline is consistently associated with poorer outcomes, including fatal anaphylaxis. No other medication reverses the underlying pathophysiology as effectively or as rapidly.
Adjunctive Measures
Supportive care includes high-flow oxygen, intravenous fluids for hypotension and bronchodilators for persistent bronchospasm.
Corticosteroids are no longer recommended for the routine management of anaphylaxis. Evidence does not support their use in treating acute symptoms or preventing biphasic reactions and routine administration risks delaying adrenaline. Corticosteroids may be considered only in selected circumstances – such as ongoing asthma symptoms after initial stabilisation – and must never delay adrenaline administration.
Antihistamines may be used for cutaneous symptoms once the patient is stable but not to treat the life-threatening features of anaphylaxis.
Intranasal Adrenaline (EURneffy): An Emerging Option
The recent MHRA approval of EURneffy in the UK, an intranasal adrenaline spray, represents an important development in anaphylaxis care. The British Society for Allergy and Clinical Immunology (BSACI) has welcomed its availability as a potential means of addressing real-world barriers to adrenaline use.
Rationale
Despite education and training, many patients do not carry or use injectable adrenaline due to needle phobia, concerns about technique, or reluctance to self-inject. EURneffy is a compact, needle-free device that may improve willingness to carry and administer adrenaline, particularly in community settings.
Evidence Base
Approval of EURneffy was based on bioequivalence studies demonstrating comparable systemic adrenaline levels and similar physiological effects on blood pressure and heart rate when compared with intramuscular injection. While reassuring, bioequivalence does not replace controlled clinical efficacy data.
Available real-world data remain limited and include small food-challenge studies and uncontrolled case series. These suggest that many reactions respond to a single dose, although the proportion meeting formal definitions of anaphylaxis varies.
BSACI Guidance and Patient Selection
The BSACI considers EURneffy suitable for most patients at risk of anaphylaxis, provided prescribing is supported by shared decision-making and clear discussion of benefits and limitations. (4) (6) (7)
However, EURneffy is not recommended as the sole rescue therapy for:
- Patients who have previously required more than one dose of adrenaline
- Patients with a history of severe anaphylaxis with hypotension, particularly insect venom allergy.
These patients should continue to have access to intramuscular adrenaline auto-injectors, although EURneffy may be used as a first-line option within an individualised management plan.
Practical Considerations
All patients prescribed EURneffy should:
- Have a written Allergy Action Plan
- Be advised to call emergency services after any adrenaline use
- Understand that ambulance services and emergency departments will continue to use intramuscular adrenaline.
EURneffy should be viewed as an additional option, not a replacement for established first-line management.
Observation and Biphasic Reactions
Biphasic reactions, defined as recurrence of symptoms after initial resolution, occur in a minority of patients. Risk factors include severe initial reactions and delayed adrenaline administration. Observation periods should be individualised, typically ranging from 6 to 24 hours depending on severity and risk profile.
Discharge Planning
Discharge following anaphylaxis is a critical opportunity to reduce future risk. Patients should not be discharged without:
- Access to appropriate adrenaline devices
- Training in their use
- A written emergency action plan
- Clear follow-up arrangements with allergy services. (4)
Long-Term Management and Risk Reduction
Education should be repeated, practical and reinforced over time. Patients and carers must feel confident recognising early symptoms and administering adrenaline promptly.
Schools and Community Settings
Clinicians play an important role in supporting schools and childcare settings through individual healthcare plans, staff training, and allergen-risk reduction strategies.
Psychological Impact
Anaphylaxis can significantly affect quality of life, leading to anxiety, avoidance behaviours and reduced independence. Adolescents are particularly vulnerable to risk-taking and non-adherence. Psychological support should be considered part of comprehensive care.
Special Populations
Infants, adolescents, and patients with poorly controlled asthma carry increased risk of severe outcomes and require particular attention to education, follow-up and risk assessment.
Key Practice Updates (Rapid Read)
- Anaphylaxis is a clinical diagnosis – do not wait for investigations
- Adrenaline is the only first-line treatment
- Delayed adrenaline use is associated with fatal outcomes
- Corticosteroids are not recommended for routine management
- Intranasal adrenaline (EURneffy) offers a needle-free option for selected patients
- EURneffy should not be the sole rescue therapy in patients with previous severe or refractory anaphylaxis
- All patients require an emergency action plan and specialist follow-up.
Conclusion
Anaphylaxis remains a medical emergency in which seconds matter. Across healthcare settings, outcomes are determined less by diagnostic certainty and more by the speed with which clinicians recognise the condition and administer adrenaline. Despite advances in allergy care, delayed or absent adrenaline use continues to account for the most serious and preventable consequences of anaphylaxis.
Recent guidance has sharpened clinical priorities. Adrenaline is unequivocally first-line. Corticosteroids have no role in routine management. Observation, discharge planning, and patient education are essential components of safe care. Emerging therapies, such as intranasal adrenaline, offer promising additional tools to address real-world barriers but must be used thoughtfully within a shared decision-making framework.
For clinicians working across primary and secondary care, anaphylaxis demands clarity and confidence: clarity in recognising evolving reactions, confidence in early adrenaline use, and commitment to empowering patients beyond the acute episode. By aligning practice with current evidence and guidance, healthcare professionals can reduce avoidable harm and ensure that patients at risk of anaphylaxis are supported to live safely and confidently.
References
- Muraro A, Worm M, Alviani C, Cardona V, DunnGalvin A, Garvey LH, Riggioni C, de Silva D, Angier E, Arasi S, Bellou A, Beyer K, Bijlhout D, Bilò MB, Bindslev-Jensen C, Brockow K, Fernandez-Rivas M, Halken S, Jensen B, Khaleva E, Michaelis LJ, Oude Elberink HNG, Regent L, Sanchez A, Vlieg-Boerstra BJ, Roberts G; European Academy of Allergy and Clinical Immunology (EAACI) Food Allergy, Anaphylaxis Guidelines Group. EAACI guidelines: Anaphylaxis (2021 update). Allergy.2022;77(2):357–377. doi:10.1111/all.15032
- Resuscitation Council UK. Emergency treatment of anaphylaxis: Guidelines for healthcare providers. Available at: https://www.resus.org.uk/library/additional-guidance/guidance-anaphylaxis
- Patel N, Chong KW, Yip AYG, Ierodiakonou D, Barta J, Boyle RJ, et al. Use of multiple epinephrine doses in anaphylaxis: a systematic review and meta-analysis. Journal of Allergy and Clinical Immunology. 2021;148(5):1307–1315.
- British Society for Allergy and Clinical Immunology (BSACI).
BSACI Statement on EURneffy (intranasal adrenaline) for the emergency treatment of anaphylaxis. 2025. - National Institute for Health and Care Excellence (NICE).
Anaphylaxis: assessment and referral after emergency treatment (CG134).
Available at: https://www.nice.org.uk/guidance/cg134 - Ebisawa M, et al. Epinephrine nasal spray improves allergic symptoms in patients undergoing oral food challenge: Phase 3 trial. The Journal of Allergy and Clinical Immunology: In Practice. 2025;13(10):2787–2794.
- Halsey G. Real-world data support effectiveness of Neffy (epinephrine nasal spray) for acute treatment of anaphylaxis. Patient Care (Online). 2025 Sep 15.