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Anaphylaxis is a severe, life-threatening systemic allergic reaction that occurs after contact with an allergy-causing substance, such as food, insect venom, medication, or other triggers. It often manifests unexpectedly and is unpredictable. However, knowledge and assessment of risk factors by patients or their caregivers can help reduce the risk of anaphylaxis and its severity. Let’s discuss the common risk factors based on medical sources and my clinical practice.

Age: Children, adolescents, and adults under 40 years are at risk for food triggers. Older age is associated with a higher risk of more severe anaphylaxis to non-food triggers, such as drug-induced anaphylaxis. Individuals aged 65 and older face an increased risk of severe anaphylaxis.

Prior Anaphylaxis: While prior anaphylaxis is not a strong predictor of future episodes, the risk of subsequent anaphylaxis still exists. The absence of prior anaphylaxis does not exclude future risk. The severity of anaphylaxis depends on various factors, including the level of allergen exposure and the presence or absence of co-factors.

Gender: Male sex is a significant risk factor. In my clinical practice, food anaphylaxis is more common in boys or men, while drug anaphylaxis is more prevalent in women.

Comorbidity and Multimorbidity: Personal history of allergy, asthma, eczema, mastocytosis, chronic obstructive pulmonary disease, thyroid disease, or previous stroke can increase the risk of anaphylaxis. Atopy may also be a risk factor for anaphylaxis triggered by food, drugs, exercise, or latex. Raised mast cell tryptase levels due to hereditary alpha-tryptasemia or mastocytosis are associated with increased severity in hymenoptera venom anaphylaxis. Recent studies have shown that patients with alpha-tryptase were more likely to experience anaphylaxis to food compared to patients who did not have it.

Concomitant Medication Use: The use of certain medications, including beta-blockers, angiotensin-converting enzyme inhibitors, antidepressants, alpha-adrenergic blockers, angiotensin II receptor blockers, monoamine oxidase inhibitors, amphetamines, and methylphenidates, has been shown to increase the risk of anaphylaxis.

Immune Activation: Viral infections can act as cofactors for other risk factors and increase the severity of allergy symptoms. Some studies have indicated that viral infections may exacerbate eczema, potentially increasing the severity of food anaphylaxis, although data are inconsistent.

Exercise: In some individuals, exercise can trigger severe food anaphylaxis, known as “Food-dependent exercise-induced allergic reactions.” During exercise following the consumption of specific trigger foods, physical activity enhances gastrointestinal permeability while reducing gastric acid production, leading to increased absorption of intact nutrients. This can activate mast cells and release inflammatory mediators and cytokines associated with anaphylaxis. Cofactors like nonsteroidal anti-inflammatory drugs or alcohol can further increase gastrointestinal tract permeability, intensifying the allergic reaction.

Disease-Modifying Treatment: Allergen immunotherapy is a minor risk factor for anaphylaxis. The risk increases with the use of multiple allergens, an accelerated treatment regimen, allergen overdose, and violations of the dosage regimen. When used correctly, the frequency of severe and fatal reactions is very low, but the risk is higher in patients with poorly controlled asthma or those taking beta-blockers.

Additionally, some information in medical literature suggests that environmental factors, travel, emotional stress, surgical interventions, and occupational exposure to antibiotics, xenobiotics, and latex may be associated with anaphylaxis risk factors, but further research is needed to confirm these associations.

Elena Ferapontova MD allergist/immunologist, European Academy of Allergy & Clinical Immunology (EAACI)