Myth 1: Anaphylaxis often results in death

Fact:
Anaphylaxis is potentially life-threatening, but fatal outcomes are extremely rare.

Key statistics:
• Fatal food anaphylaxis occurs annually just 1–2 people per million
• Hospital admissions for anaphylaxis have increased dramatically in recent decades
• Despite rising incidence, overall fatality rates have remained relatively stable.

Most patients recover completely when anaphylaxis is recognised early and treated promptly with adrenaline.

However, fatal outcomes are strongly associated with:
• Delayed recognition
• Delayed adrenaline administration
• Poor asthma control
• Ongoing allergen exposure.

Clinical explanation:
One of the major misconceptions is that anaphylaxis almost always leads to death. In reality, severe outcomes are uncommon when treatment is prompt. However, it is extremely difficult to reliably predict which reactions may deteriorate rapidly. Consequently, if in doubt give Adrenaline quickly.

Safeguarding implications:
All suspected anaphylaxis reactions must still be treated as medical emergencies because deterioration can occur suddenly and unpredictably.

Myth 2: Most anaphylaxis is caused by foods

Fact: The causes of anaphylaxis vary according to age and setting.

Key statistics and evidence:
In children:
• Food is the leading trigger
• Common allergens include milk, eggs, peanuts, tree nuts and sesame.

In adults:
• Medications become increasingly important causes
• Antibiotics, NSAIDs and intravenous medications are common triggers
• Insect stings are also significant causes.

Milk is often a major trigger of severe reactions in children. Medication-triggered anaphylaxis is more common in healthcare settings.

Safeguarding implications:
Schools and early years settings require robust food allergy management systems and staff training.

Myth 3: Anaphylaxis is easy to recognise

Fact:
Anaphylaxis is frequently under-recognised, misdiagnosed and undertreated.

Anaphylaxis is a clinical diagnosis. The most common trigger in young people is food: symptoms typically begin within 15–30?min of exposure and progress rapidly.

Other triggers, such as medication or insect stings, are far less common in children. In around 20% of cases, no trigger is identified; this is known as idiopathic anaphylaxis.

Important evidence:
Symptoms may mimic:
• Asthma
• Viral illness
• Gastroenteritis
• Panic attacks
• Fainting.

The review emphasises that:
• Symptoms can initially appear mild
• Patients may deteriorate rapidly
• There is no single diagnostic test that reliably confirms acute anaphylaxis in the emergency setting.

Food-related anaphylaxis is the most common trigger for anaphylaxis in children aged 0–19 years.

Anaphylaxis in infants and children most commonly presents with respiratory symptoms. Fatal anaphylaxis primarily due to a breathing problem. Hypotension/ low blood pressure is a very late and rare sign of anaphylaxis in children.

Because anaphylaxis in children often present with persistent cough and wheeze, it is often incorrectly initially treated with salbutamol and corticosteroids as first-line therapy, which delays the administration of intramuscular adrenaline, with risk of increased morbidity and mortality.

 Adrenaline is the only first-line therapy for anaphylaxis. Any additional therapy should be given only after adrenaline administration.

Anaphylaxis presents differently between individuals. Some patients present with obvious airway compromise and collapse, while others initially develop only vomiting, coughing or feeling unwell.

Examples:
Vomiting may initially be mistaken for illness rather than allergy. Wheezing may incorrectly be treated as isolated asthma.

Safeguarding implications:
Staff training is critical because delayed recognition remains a major contributor to fatal outcomes.

Myth 4: Skin symptoms must be present for anaphylaxis

Fact: Many people experiencing an anaphylactic reaction may not have hives, swelling or a rash.

Key statistics:
Approximately 10–20% of anaphylaxis cases occur without:
• Rash
• Hives
• Facial swelling.

Other symptoms may include:
• Vomiting
• Wheezing
• Breathing difficulty
• Hypotension
• Collapse
• Sudden deterioration.

Airway, breathing, gastrointestinal or circulation symptoms may all occur in isolation.

If in doubt, give adrenaline.

Book our First Aid for Anaphylaxis and Acute Allergic Reaction online course or email emma@firstaidforlife.org.uk to arrange practical trainning to ensure you are fully trained and confident dealing with anaphylaxis.

Myth 5: Gastrointestinal symptoms are not serious

Fact: Gastrointestinal symptoms alone can be early signs of severe allergic reaction.

Key symptoms can include:
• Vomiting
• Abdominal pain
• Cramping
• Diarrhoea.

Gastrointestinal symptoms are particularly common in food-triggered reactions and may occur before respiratory or circulatory symptoms.

Important safeguarding lesson: Vomiting in a child with known severe allergies should always be considered as possible anaphylaxis.

Symptoms can escalate rapidly from vomiting and abdominal pain to airway compromise, collapse and cardiac arrest.

If in doubt, give adrenaline.

Myth 6: Mild reactions cannot become severe

Fact: Previous mild reactions do not reliably predict future severity.

Important evidence:
Patients with previously mild reactions may later experience severe or fatal anaphylaxis.

Risk factors increasing severity include:
• Asthma
• Delayed treatment
• Continued allergen exposure
• Teen and young adult age groups.

One of the major challenges in allergy management is unpredictability. Clinicians cannot accurately predict which future reactions may become severe.

Even apparently mild symptoms require close monitoring and rapid escalation if symptoms worsen.

Myth 7: Adrenaline is dangerous

Fact: Intramuscular adrenaline is the first-line treatment and is generally very safe when used correctly.

Key evidence:
• Delayed adrenaline administration is strongly associated with fatal outcomes
• Serious adverse effects from intramuscular adrenaline are rare
• Fear of giving adrenaline unnecessarily contributes significantly to treatment delays.

Clinical explanation:
Adrenaline rapidly:
• Reduces airway swelling
• Improves blood pressure
• Relaxes airway muscles
• Slows progression of reaction.

Important facts:
• Intramuscular injection into the outer thigh is recommended
• Adrenaline should be given immediately when anaphylaxis is suspected.

Intranasal adrenaline – neffy will also treat anaphylaxis.

Safeguarding message: The risk of delaying adrenaline is far greater than the risk of giving it unnecessarily.

Myth 8: Antihistamines can treat anaphylaxis

Fact: Antihistamines do not treat the life-threatening features of anaphylaxis.

However, antihistamines may help with:
• Itching
• Rash
• Hives.

But do not treat:
• Airway swelling
• Shock
• Breathing difficulty
• Circulatory collapse.

Administration of other medications in the treatment of anaphylaxis delays the administration of adrenaline, which is the current best available first-line therapy for anaphylaxis.

Anti-histamines are H1 receptor antagonists and are a generally helpful treatment for urticaria and itch caused by the release of histamine from mast cells. They do not prevent progression to, or treat, airway obstruction, hypotension or shock.

Antihistamines should not be used as first-line treatment for anaphylaxis because they delay the administration of adrenaline but can be useful additional therapy once adrenaline has been administered. There is no evidence that prophylaxis with oral antihistamines decreases the risk of severe allergic reactions on subsequent exposure to food allergens

Antihistamines are often overused and wrongly indicated and this can lead to a potentially dangerous delay in giving adrenaline.

Histamine is only one of many inflammatory chemicals released during anaphylaxis. Oral antihistamines take around 30?min to work; intravenous chlorphenamine acts faster but can cause low blood pressure.

Antihistamines are not effective against anaphylaxis, either as a preventative drug or in the treatment. Any apparent response during acute management of reactions is most likely due to the patient’s own intrinsic adrenaline.

Antihistamines have now been relegated to third line therapy in international guidelines; they should only be prescribed for mild allergic reactions such as hay fever and to relieve skin symptoms and should never delay the administration of adrenaline.

Antihistamines can reduce mild skin symptoms but do not reverse any underlying severe allergic reaction. They should not be used as a first line treatment or second line and are merely indicated for mild allergic reactions.

Important safeguarding point:

Antihistamines must never replace adrenaline in suspected anaphylaxis.

Myth 9: Only children who have had anaphylaxis need an adrenaline autoinjector

Allergy skin prick tests and/or allergen-specific IgE blood tests do not predict the severity of a potential reaction. Anaphylaxis can occur in patients with high, low and even negative tests. A recent European Consensus concluded that it is very difficult if not impossible to accurately predict who is at risk of severe anaphylaxis: a number of risk factors acting together are involved.

Various risk factors for severe anaphylaxis have been proposed, based on limited case series of fatal anaphylaxis:

Food-induced anaphylaxis is most common in the 0–5 age group, but death from anaphylaxis in this age group is rare.

Teenagers and young adults appear to be more likely to experience severe outcomes, which cannot be easily explained by risk-taking behaviour.

Asthma is considered a risk factor; however, in the UK Fatal Anaphylaxis Registry, 22% of cases did not have a prior diagnosis of asthma.

Around 50% of children with food allergies have asthma: the vast majority will never have a severe allergic reaction thus asthma has poor predictive value for severe reactions. Although it is particularly vital to carefully control asthma in food-allergic individuals.

Delays in administering adrenaline is the most important risk factor for fatal outcome: and it is this, as well as the inability to predict severe reactions, which makes adrenaline autoinjectors so important.

However, it is vital that the autoinjectors are immediately available at all times, otherwise the prescription is pointless.

Myth 10: It is okay for the person to walk to the first aid room to be given their autoinjector

Correct positioning of the patient is important in anaphylaxis as highlighted in MHRA guidance.

Lying the patient on their back with their lower limbs elevated will increase venous return and cardiac output. Patients struggling to breathe should be allowed to sit, with their lower limbs elevated where possible.

Sudden standing must be avoided, and patients with anaphylaxis must not be instructed to walk to a first aid room to use their autoinjector, as this may increase the risk of death. Once lying down it is of critical importance that they do not get up until supervised to do so by the emergency services. Standing up can lead to collapse and can prove catastrophic.

Myth 11: Patients recover completely once symptoms improve

Fact:
Symptoms may recur after apparent recovery.

Key statistics:
• Biphasic/ recurrent reactions may occur within 1–72 hours
• Most occur within the first 8 hours.

Important evidence:
The review explains that recurrence can occur after initial improvement, which is why observation after significant reactions is important.

Observation recommendations:
Observation periods may range from:
• 2–24 hours depending on severity and risk factors.

Clinical explanation:
A patient may initially appear well following adrenaline administration before symptoms return later.

Important safeguarding implication:
Improvement after treatment does not always mean the danger has fully passed.

Myth 12: Only people with known allergies experience anaphylaxis

Fact:
Anaphylaxis may occur during a person’s first known allergic reaction.

Key statistics:
• Approximately 25% of severe allergic reactions in schools occur in children with no previously known allergy history.

Important evidence:
Some reactions occur:
• Without prior diagnosis
• Without a clearly identified trigger.

Over one-third of allergic reactions occur to a food with no known prior ingestion.

However, it is immunologically required to have been exposed to antigen/allergen in order to trigger the immune response that leads to an anaphylactic reaction. This initial exposure (and sensitisation for people with allergies) to an allergen may occur through the gut via allergens in breast milk, the skin particularly in children with a breakdown in the normal skin barrier such as infants with eczema, or more rarely via the respiratory tract without ever having knowingly been previously exposed to the allergen in question.

Individuals may have previously experienced only mild symptoms or no symptoms at all before severe reaction occurs.

Safeguarding implications: Schools, nurseries and public spaces must be prepared even for individuals without diagnosed allergies.

Myth 13: Anaphylactic reactions get worse each time

The severity of an allergic reaction depends on many different factors which are not currently fully understood. For food allergies these include: the amount of food eaten and what it was eaten in; what else was eaten at the same time; and if the person has any other medical illnesses such as asthma or a cough/cold.

We cannot predict who will have a life-threatening anaphylaxis reaction, which is why anyone with symptoms of anaphylaxis should receive immediate treatment with adrenaline.

Key Messages

The review strongly supports several major clinical and safeguarding principles:

• Early recognition saves lives
• Vomiting can be an early sign of anaphylaxis
• Skin symptoms may be absent
• Delayed adrenaline administration increases fatality risk
• Adrenaline should be given early when anaphylaxis is suspected
• Severe reactions are unpredictable
• Staff training and awareness are critical
• Schools and childcare settings must be prepared for reactions in individuals with no known allergy history.

Main Source:

Anagnostou K, Turner PJ.
Myths, facts and controversies in the diagnosis and management of anaphylaxis.
PubMed Central (PMC) BMJ: https://pmc.ncbi.nlm.nih.gov/articles/PMC6317446/

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Author: Emma Hammett