Epidemiology

Anaphylaxis is under-reported and it is difficult to estimate as study definitions and criteria are not always comparable.[2][7][8][9] US and European studies estimate lifetime prevalence of anaphylaxis to be between 1.6% and 5.1%, with an incidence rate of 42 per 100,000 person-years.[10][11][12][13][14] These estimates vary widely, due to varying populations, different methods of identification, and a plethora of classifications. Incidence and prevalence differ for specific allergens.

NHS Digital figures show that anaphylaxis hospital admissions in England for all causes in children and young people under 18 has risen by around 70% (from approximately 1000 to almost 1400) in the past 5 years (from 2013-2014 to 2018-2019). Hospital admissions for adult anaphylactic shock have also increased from about 12,300 in 2002-2003 to 26,000 in 2022-2023, a more than 100% increase.[15]

The incidence of food allergic reactions that are coded as anaphylaxis is highest in young children.[16] In children, food allergy is most prevalent in the industrialised world and the emerging economies of southeast Asia, possibly due to increased exposure to processed food. Food allergy affects both sexes equally.[17] There are reports of slightly higher rates of anaphylaxis to food in males in Hong Kong and in females in Australia.[18][19] In North America, Europe, and Australia, food-induced anaphylaxis is thought to account for one third to one half of anaphylaxis cases presenting to emergency departments.[20]

Medicines, notably penicillin and non-steroidal anti-inflammatory drugs, are common causes of anaphylaxis in adults.[21][22][23]

Risk factors

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<30 years old: food-associated, exercise-induced

Food-associated, exercise-induced anaphylaxis is more common in young people.[20]

atopy/asthma

Atopy is a risk factor for food-induced anaphylaxis, and has been associated with increased risk of life-threatening reactions.[38][39]

Asthma is a risk factor for anaphylaxis; more severe asthma increases the risk for anaphylaxis.[2][40]

history of anaphylaxis

Individuals with previous anaphylactic reactions are at higher risk for recurrence.[41]​​[42] However, the severity of a previous reaction does not necessarily predict the severity of a subsequent reaction.[43]

exposure to a common sensitiser (e.g., latex)

Exposure history to latex and latex sensitivity occurs in a significant percentage of health care workers.[44]

Patients with spina bifida and those undergoing multiple surgeries are at increased risk of latex allergy.[45][46]

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adult age: food-, insect venom- and medicine-related

Reactions to shellfish are the most commonly reported food-associated reactions in adults.[34]

Among 1598 adult patients (aged ≥15 years) with a discharge diagnosis of food-induced anaphylaxis, two-thirds of cases were among women (n=978).[35] The highest rates of food-induced anaphylaxis were among people aged 25 to 34 years (n=361), and the lowest among older adults (aged ≥65 years).

Fatal venom-associated anaphylaxis is predominantly seen in adult men aged 50 to 60 years.[36][37]

Medicines, notably penicillin and non-steroidal anti-inflammatory drugs, are common causes of anaphylaxis in adults.​[21][22][23]

female sex

Food-associated, exercise-induced anaphylaxis is more common in women.[20]

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