Shellfish allergy is one of the most common food allergies reported by U.S. adults. In a JAMA Network Open survey, 2.9% of U.S. adults had a convincing shellfish allergy, while 1.9% had a convincing shrimp allergy. Rates vary substantially by age, country, study method, and whether a result reflects a reported history or a food challenge.
Contents
- Key shellfish allergy numbers
- Prevalence among U.S. adults
- Children, adolescents, and age of onset
- International comparisons
- Severity, emergency care, and epinephrine
- Crustaceans, mollusks, and seafood overlap
Key shellfish allergy numbers
The most useful headline figures come from several different populations, so they should not be treated as interchangeable. The JAMA Network Open adult survey measured convincing current food allergy in U.S. adults. Other figures come from children’s reviews, referral populations, questionnaire studies, and food-challenge studies.
- 2.9% of U.S. adults had convincing shellfish allergy, the most common convincing food allergy in that survey. (JAMA Network Open)
- 1.9% of U.S. adults had shrimp allergy. (JAMA Network Open)
- 1.6% had mollusk allergy, while 1.3% had lobster allergy and 1.3% had crab allergy. (JAMA Network Open)
- 2.4% of U.S. adults had crustacean allergy in an adult shellfish study. (PMC adult shellfish allergy study)
- 1.3% of U.S. children had shellfish allergy; crustacean allergy was 1.2% and mollusk allergy was 0.5%. (ScienceDirect pediatric US study)
- Canadian researchers found 1.42% probable shellfish allergy overall, but 0.73% when food-challenge confirmation was used. (PubMed Canada study)
- The Asia-Pacific review estimated overall shellfish allergy prevalence in the western world at about 0.6%. (Asia-Pacific review)
- The ACAAI says shellfish allergy affects nearly 7 million Americans. (ACAAI)
These values differ because “probable,” “convincing,” “reliable history,” and food-challenge-confirmed allergy are different measurements. A questionnaire can identify people who report a reaction, while a supervised challenge applies a stricter confirmation method.
Prevalence among U.S. adults
The adult JAMA Network Open survey found shellfish allergy in 2.9% of U.S. adults overall. Its age-specific results show that shellfish allergy remained common across the adult lifespan rather than appearing only in one narrow age group.
| U.S. adult age group | Shellfish allergy | Shrimp allergy |
|---|---|---|
| Overall | 2.9% | 1.9% |
| 18–29 | 2.8% | 1.8% |
| 30–39 | 3.6% | 2.5% |
| 40–49 | 2.5% | 1.8% |
| 50–59 | 3.3% | 2.2% |
| 60+ | 2.6% | 1.6% |
The highest reported adult shellfish rate in this age breakdown was 3.6% among adults aged 30–39. The lowest was 2.5% among adults aged 40–49. Adults aged 18–29 had a rate of 2.8%, and adults aged 60 and older had a rate of 2.6%. The corresponding shrimp rates ranged from 1.6% among adults aged 60 and older to 2.5% among adults aged 30–39. (JAMA Network Open)
The same survey found that 5.2% of U.S. adults had adult-onset current food allergy overall. Among convincingly food-allergic adults, 48.0% reported adult-onset food allergy. These figures describe food allergy broadly, not shellfish alone, but they show why shellfish reactions can first appear after childhood.
Shellfish-specific adult research reported a mean age of diagnosis of 17.7 years, while the mean age of diagnosis for adult-onset shellfish allergy was 28.3 years. A separate review summarized a median onset of 25 years among 122 Canadian adults with shellfish allergy. (PMC adult shellfish allergy study; Asia-Pacific review)
Children, adolescents, and age of onset
In the U.S. children survey, shellfish allergy prevalence was 1.3% overall. Shrimp allergy was 1.2%, and crustacean allergy was also 1.2%, compared with 0.5% for mollusk allergy. (ScienceDirect pediatric US study)
The international child figures vary widely. In Singapore, self-reported shellfish allergy among native children rose from 1.19% at ages 4–6 to 5.23% at ages 14–16. Among expatriate children in the same age bands, the figures were 0.55% and 0.96%. These are self-reported results and should not be compared directly with food-challenge-confirmed estimates. (Clinical and Translational Allergy review)
A Canadian population study found probable shellfish allergy in 0.50% of children and food-challenge-confirmed allergy in 0.06%. Among Canadian adults, the corresponding rates were 1.70% and 0.70%. In Denmark, a cohort found 0.10% shellfish allergy by questionnaire among people aged 0–22, with 0% confirmed by challenge. For ages 22–60, the questionnaire figure was 1.1%, compared with 0.30% by challenge. (PubMed Canada study; Asia Pacific review table)
The 2024 Frontiers review reported that pediatric shellfish allergy in the U.S. increased from 0.5% in 2004 to 1.3% in 2019. The review also listed shrimp allergy at 5.5% among U.S. children aged 5–17 in one cited study. These figures come from different measurements and study contexts, so the trend figure should not be used as a universal estimate for every child. (Frontiers review)
Natural resolution also differs by study design. One questionnaire study including adults and children found resolution in as few as 3.9% of patients. A food-challenge study of children with non-anaphylactic reactions found natural resolution as high as 46%. (PMC children review)
International comparisons
Country-level results show why geography and methodology matter. A French study of children aged 2–14 found shellfish allergy prevalence of 1.4%. A U.S. study of people aged 18–61 found 2.60% by reliable history, while another U.S. population study of all ages found 2.00% by reliable history. A U.S. sample aged 0–18 found 0.70% by reliable history. (Asia Pacific review table)
The Asia-Pacific review listed shellfish allergy at 1.28% among Hong Kong children aged 2–7, 0.20% among preschool children in Chongqing by reliable history and challenge, and 0.40% among Australian infants under 1 year. Another study cited in the 2024 review reported 0.10% in Hong Kong. (Asia-Pacific review; Frontiers review table)
Shrimp-specific estimates were broader still:
- South Asia: 3.4% among children aged 3–7.
- China: 4.4% among preschool children.
- Guangzhou, China: 0.18% in one cited study.
- India: 15.5% by weighted population in one adult study, and 3.2% in a subgroup with total IgE below the median.
- Northern, Central, and Southern Italy: 4%, 13%, and 16%, respectively, in one cited study.
- Denmark: 2% in one cited study.
- Ghana: 0.1% among children aged 5–16.
- Worldwide: 0.3%–0.6% in one summarized source.
(Frontiers review table)
The Asia-Pacific review also stated that shellfish made up one quarter of seafood supply in the region and described prawns as 62% of shellfish allergy cases, ahead of crab, lobster, and mollusks. (Asia-Pacific review)
Severity, emergency care, and epinephrine
Shellfish allergy statistics also describe the potential seriousness of reactions. In the JAMA Network Open adult survey, 51.1% of convincingly food-allergic adults reported severe reactions to at least one allergen. 38.3% reported at least one lifetime food allergy-related emergency department visit, while fewer than 10% reported such a visit in the past year overall. (JAMA Network Open)
About 45% of shellfish-allergic adults reported visiting an emergency department at least once in their lifetime in an adult shellfish study. The 2024 Frontiers review described accidental shrimp exposure as a major cause of emergency-room visits and stated that anaphylaxis occurred in up to 50% of people with shrimp allergy. (PMC adult shellfish allergy study; Frontiers review)
The children’s review reported skin and oral symptoms in 60%–95% of shellfish-allergic patients, gastrointestinal symptoms in around 20%, respiratory symptoms in 5%–23%, and anaphylaxis in 21%–33%. Shellfish-induced anaphylaxis prevalence among children was reported as 0.55% in Asia, 0.72% in North America, and 0.11% in Europe. (PMC children review)
Among food-allergic U.S. adults overall, 24.0% reported a current epinephrine prescription. For comparison, 62% of sesame-allergic adults reported one, and 65% of adults with severe physician-diagnosed food allergy plus a past-year emergency visit reported one. These are comparison figures for the broader food-allergy population, not shellfish-specific prescription rates. (JAMA Network Open)
The adult shellfish study found that Black non-Hispanic adults with shellfish allergy had increased odds of severe reactions, with an odds ratio of 1.9. For Black non-Hispanic adults with crustacean allergy, the odds ratio was 2.2. Adults older than 60 had reduced odds of severe shellfish reactions, with an odds ratio of 0.5; for older adults with mollusk allergy, the odds ratio was 0.3. Odds ratios describe relative odds in the study population, not an individual person’s probability. (PMC adult shellfish allergy study)
Crustaceans, mollusks, and seafood overlap
Shellfish is a broad category that includes crustaceans such as shrimp, crab, and lobster and mollusks such as clams and related species. In the JAMA Network Open adult survey, prevalence was 1.9% for shrimp, 1.3% for crab, 1.3% for lobster, 1.6% for mollusks, and 0.3% for other shellfish. (JAMA Network Open)
In a Texas adult allergy-referral population, seafood allergy prevalence was 3.08%, with shellfish dominating the seafood cases. Among seafood-allergic adults, 59.1% had shellfish allergy rather than fish allergy, 13.8% had fish allergy only, and 6% had both fish and shellfish allergy. Among female seafood-allergic patients, 57.3% reported shellfish allergy, 13.4% had fish allergy, and 6.1% had both. (Texas Medical Center 13-year experience)
Shellfish can also coexist with other food allergies. In the JAMA Network Open survey, 45.3% of convincingly food-allergic U.S. adults reported multiple convincing food allergies, and 47.5% reported a physician-diagnosed convincing food allergy. About 60% of people with shellfish allergy reportedly experience their first reaction as adults. (JAMA Network Open; FoodAllergy.org)
Taken together, the figures show a consistent pattern: shellfish allergy is common among reported adult food allergies, shrimp is a major contributor, prevalence estimates are higher when based on history than challenge confirmation, and severe reactions and emergency care are important parts of the measured burden. Differences by age, geography, population, and diagnostic method are essential when comparing any two shellfish allergy statistics.