Anaphylaxis affects an estimated 0.3% to 5.1% of people at some point in their lives, with roughly 50 to 112 episodes occurring per 100,000 people each year worldwide. That’s a wide range, partly because definitions and reporting methods vary by country, but it means anaphylaxis is far from rare. It’s also becoming more frequently diagnosed, particularly among young children.
Overall Incidence and Lifetime Risk
The global incidence of anaphylaxis sits between 50 and 112 episodes per 100,000 people per year, according to the World Allergy Organization. To put that in perspective, in a city of one million people, somewhere between 500 and 1,120 anaphylactic reactions would be expected annually. The lifetime prevalence of up to 5.1% means that as many as 1 in 20 people may experience anaphylaxis at some point, though many of those cases are mild enough to resolve without hospitalization.
These numbers have been climbing. Hospital admissions for anaphylaxis have risen in most regions over the past two decades, though this likely reflects a combination of genuinely increasing cases and better recognition by both patients and clinicians. Importantly, while more people are being treated for anaphylaxis, the death rate has not risen alongside it. In many regions, it has actually declined.
How Rates Differ by Age
Adults experience anaphylaxis more often than children. A large meta-analysis found about 53 cases per 100,000 people per year in the general population, compared to just 5 per 100,000 in children and 20 per 100,000 in adults when those groups were analyzed separately. Children are significantly less likely to have anaphylactic reactions overall, though the triggers they face look different from those affecting adults.
One notable trend involves infants. Emergency room visits for food-induced anaphylaxis among babies under age 1 have been rising steadily. Between 2013 and 2024, infants had 27% higher odds of a food-related anaphylaxis ER visit each year, and in the most recent period studied, infants were more than twice as likely to visit the ER for a food reaction compared to a decade earlier. This increase was not seen in children aged 2 to 5, suggesting something specific to the infant age group, possibly related to earlier introduction of allergenic foods and increased awareness among parents.
What Triggers Most Cases
Three categories account for the vast majority of anaphylaxis: insect stings, food, and medications. An analysis of over 4,000 confirmed cases from central Europe found that insect venom caused about 50% of all anaphylactic reactions, food caused 25%, and medications caused 15%.
The trigger profile shifts dramatically with age. In children, food is the dominant cause. In adults, insect stings take over as the leading trigger. This pattern holds across most studies worldwide, though the specific foods and insects involved vary by region.
Among food allergies broadly, the most common culprits are peanuts (affecting about 2.2% of the population), cow’s milk (1.9%), shellfish (1.3%), and tree nuts (1.2%). Among children with food allergies, over 42% have reported at least one severe reaction, and nearly 40% are allergic to more than one food.
Cases With No Identifiable Trigger
Sometimes anaphylaxis strikes and no cause can be found. These “idiopathic” cases account for anywhere from about 6% to 20% of all anaphylactic reactions in most studies, though some older estimates ran as high as 41%. More advanced diagnostic testing has been shrinking that number. One registry found that its idiopathic rate dropped from 9.2% to 3.5% after more thorough evaluation, suggesting that many mystery cases do have a trigger that initial testing simply missed.
How Often Anaphylaxis Is Fatal
The case fatality rate for anaphylaxis that results in hospitalization is approximately 0.5% to 1%. That figure has remained surprisingly consistent across different countries and time periods. In population terms, roughly 0.5 to 1 person per million dies from anaphylaxis each year in regions where data are available.
Australia stands out as an exception: fatal anaphylaxis rates there increased by about 6.2% per year from 1997 to 2013, driven mostly by food-triggered reactions. However, even in Australia, when researchers looked at the proportion of hospitalized patients who died (rather than total deaths), the rate had actually fallen. More people were being admitted, but a smaller fraction were dying, reflecting improvements in emergency treatment.
Biphasic Reactions
About 9% of people who experience anaphylaxis will have a second wave of symptoms hours after the initial reaction appears to resolve. These biphasic reactions are the reason patients are typically monitored for several hours after treatment. Most second reactions are milder than the first. Only about 3% of anaphylaxis patients experience a biphasic reaction severe enough to meet the full diagnostic criteria for anaphylaxis again, and just 1% develop dangerous changes in blood pressure or heart rate during the second phase.
Anaphylaxis During Surgery
Anaphylaxis during surgical procedures is rare but carries higher stakes because the patient is under anesthesia and may not show typical warning signs like hives or throat tightness. The estimated incidence is about 1 in 7,000 procedures, with a mortality rate of roughly 2% in the United States. For patients who have previously experienced anaphylaxis during surgery and later undergo another procedure, the recurrence rate is below 2%, particularly when a thorough allergy workup has been done beforehand.