Crab allergy

By Symon, Every Label · June 30, 2026

Crab allergy is an IgE-mediated immune reaction to proteins in crab, most often the muscle protein tropomyosin, and it is one of the crustacean shellfish allergies, the group that most often causes severe seafood reactions. In plain terms: your child’s immune system reads certain crab proteins as a threat, and a reaction can run from hives to a whole-body allergic reaction that affects breathing and blood pressure, called anaphylaxis. It is a true allergy, not a sensitivity or an intolerance. Shellfish allergy affects an estimated 1.3 percent of US children, with crustacean shellfish allergy at about 1.2 percent (Wang and Gupta 2020). Two things set crab apart from the early-childhood allergies like milk and egg: it more often begins later, in school-age children and even in adulthood, and once it is established it is rarely outgrown.

If your child was just diagnosed, read this first.

This page is long on purpose. It is also the page you will come back to for years. You do not need all of it today. This week, this is what matters:

• Carry two epinephrine auto-injectors everywhere your child goes, and learn the few signs that mean use one now. That is the section to read tonight (Emergency preparedness, below). If you do not have the prescription yet, that is the first call to your allergist or pediatrician.
• Read every label, every time. The words to catch are crab, crustacean shellfish, and the species names (blue crab, snow crab, dungeness, king crab), and the hidden ones are surimi or imitation crab, shellfish stock, and seafood extract (Reading labels, below).
• The other crustaceans travel with crab. Shrimp, lobster, and crayfish share the same main protein, and most people allergic to one react to the others, so treat the whole crustacean group as off the list until an allergist says otherwise (Cross-reactivity, below).
• Molluscs (clams, oysters, mussels, scallops, squid) are a separate, lower question, not an automatic yes and not an automatic no. They are tested, not assumed (Cross-reactivity, below).
• One myth to clear right now, because it can cause real harm: shellfish allergy is NOT an iodine allergy, and it is not a reason to refuse a CT contrast dye or an X-ray dye. Tell any doctor your child has a shellfish allergy, but do not let anyone withhold contrast over it (Hidden sources, below).
• You do not have to understand the protein science to keep your child safe. The component and test details are for unhurried conversations with your allergist.

Everything else here is waiting for you, in roughly the order the questions tend to come up. Read it when you want it.

Where a fact below is clinical, it carries its source. None of it is a substitute for your allergist.

What crab allergy is, and who has it

Crab allergy is an IgE-mediated immediate-type food allergy, and crab is one of the crustacean shellfish, the dominant group within shellfish allergy. That is the reason for everything practical on this page: the auto-injectors, the label habit, the written plan. When your child eats crab, IgE antibodies on their immune cells latch onto the crab proteins, mostly the muscle protein tropomyosin, and trigger a release of histamine and other chemicals within minutes. That release is the reaction. Cooking does not defuse it: tropomyosin is heat-stable and digestion-stable, so boiled, steamed, canned, and dried crab all keep the allergen.

Crab is a crustacean, a shellfish, and it is not a fish. That distinction matters and it gets confused constantly. Finned fish like salmon, cod, and tuna carry a completely different main allergen, and a crab allergy does not by itself mean a fish allergy (Cross-reactivity, below). Crab is also separate from the molluscs (clams, oysters, mussels, scallops, squid), which are a different and lower question. The group that genuinely travels with crab is the other crustaceans: shrimp, lobster, and crayfish.

One epidemiological fact shapes this whole page: shellfish allergy is more an adult-onset than an early-childhood disease. Crab is not broken out on its own in the big surveys, so the figures here are crustacean-category figures, qualified as such, not crab-specific. In US children the estimated prevalence of shellfish allergy is 1.3 percent, with crustacean shellfish allergy at about 1.2 percent, in a nationally representative survey of 38,408 children (Wang and Gupta 2020). In US adults the estimated prevalence is higher, with shellfish the single most common adult food allergy at about 2.9 percent, and a large share of shellfish-allergic adults say the allergy began in adulthood (Gupta 2019). So a child without a crab allergy today is not guaranteed to stay that way, and a teenager or adult can develop one new.

Diagnosis combines your child’s history with testing, and for crab the testing has one honest limit worth knowing about up front. The next section is what that means.

The components that drive severity

Crab is not one thing to the immune system. It is a handful of proteins, and which one your child reacts to shapes how serious the allergy tends to be. For crab there is one protein that carries most of the weight, and there is also an honest limit to what the blood number can tell you.

A standard crab test (the skin prick, or the basic blood test) only tells you the immune system has noticed crab at all, and it carries a lot of false positives, partly because dust-mite allergy can light up the same shared protein. A more detailed test, component testing, breaks the result down protein by protein. For crab the protein that matters most is the one your allergist calls tropomyosin. Sensitization to it is the strongest single signal for a systemic, whole-body reaction, and it is also the protein that crab shares with the other crustaceans and with dust mites.

Here is the honest part that crab does not share with peanut. There is no single blood-test number for crab that decides the allergy the way the peanut number can. The component tests are more accurate than the whole-crab test, but the cutoffs differ by population and the crustacean tropomyosin assays are less standardized, so a tropomyosin result does not clear or condemn a child on its own. Crab also has no well-established “usually mild” component to reassure you with. So the high-value move is to ask your allergist about component testing and what your child’s pattern means, while knowing the number is a conversation, not a verdict the page can set.

Cross-reactivity, real and cautionary

This is the section where crab’s allergy is wider than parents hope, so the honest version leads with the caution, not a reassurance. Crab’s main protein, tropomyosin, is shared across a whole web of related animals, and the cross-reactions that matter are real. The good news that exists is narrow and specific, and it comes after the part that changes the plate. This page names the lead claims and the practical rule; the full molecular picture lives in the deep cross-reactivity pages.

The other crustaceans travel with crab. Shrimp, lobster, and crayfish (crawfish) share tropomyosin with crab at very high sequence identity, between 91 and 100 percent, and more than three in four people allergic to one crustacean react to the others. The practical rule most allergists use is to treat the whole crustacean group, including shrimp dishes, lobster, and crawfish boils, as off the list unless a supervised challenge with your allergist says otherwise.

Molluscs are a separate, lower question, tested not assumed. Clams, oysters, mussels, scallops, and squid are molluscs, a different animal group from crustaceans. Cross-reactivity from crustaceans into the molluscs is real but lower and far less uniform than the crustacean-to-crustacean kind: people allergic to crustaceans do sometimes react to snails and other molluscs through shared tropomyosin, but a crab allergy does not automatically mean a mollusc allergy. This is the place not to guess in either direction. A positive mollusc test is a reason to ask your allergist, not a reason to assume the food is either safe or off-limits, and the page will not tell you that you can eat other shellfish, because the cleared evidence does not support a blanket reassurance.

Dust mites and cockroaches share the same protein, which matters for the nose, not the plate. Tropomyosin is not only in shellfish. House dust mite and cockroach carry a homologous tropomyosin, so a crab test can cross-react with them. For most families this is why a dust-mite-allergic child can test positive to crab without ever having reacted to it, and it is the reason whole-crab tests carry false positives. It also carries one specific, important caution that lives in the exposure section: a shellfish-allergic child who is a candidate for dust-mite allergy shots for asthma or hay fever should have that overlap discussed first, because the shot extract contains the same protein.

Crab is not fish. Crustacean shellfish allergy does not mean a finned-fish allergy. The main allergens differ (tropomyosin in shellfish, parvalbumin in fish), and clinical cross-reactivity between the two is low, so a crab-allergic child does not have to avoid salmon, cod, or tuna on that basis, though cross-contamination in a shared fryer or kitchen is still possible. Confirm with your allergist, but these are two different allergies, not one.

For the depth, the molecular family picture (which proteins, how high the cross-reactivity runs, and how the crustacean group is managed) is the crustacean shellfish cross-reactivity page, and the shared-tropomyosin web that links shellfish, dust mite, and cockroach, including the allergy-shot caution, is the tropomyosin syndrome page.

Hidden sources

Crab and crustacean protein hide in dense, often-unlabeled places, and this section is worth a one-time read now. After that you will spot them on your own, and the full label-scanning guide is on where crab hides. There is also one myth to clear here that can cause real medical harm, so it leads.

The shellfish-iodine myth, cleared because it matters. Shellfish allergy is NOT an iodine allergy. Iodine is not an allergen at all, and a shellfish allergy does not raise the risk of reacting to the iodinated contrast dye used in CT scans and X-rays more than any other allergy does. This is not trivia. Children and adults are still sometimes refused contrast imaging, or premedicated unnecessarily, because of a shellfish allergy on the chart. Tell every doctor your child is allergic to shellfish, and disclose any prior reaction to a contrast dye itself, but a shellfish allergy is not a reason to withhold contrast. If anyone tries to, this is the fact to bring.

Carmine is not shellfish. Carmine, also called cochineal or E120, is the red food and cosmetic dye made from the cochineal insect, not from any shellfish. It can rarely be its own allergen, but it is unrelated to a crab allergy.

Surimi and imitation crab are a double trap. Surimi, sold as imitation crab or “krab,” is usually made from pollock, a finned fish, so the name says crab while the base is fish. But it is commonly crab-flavored or carries crustacean extract, and it is processed on shared crustacean equipment, so it is not reliably crab-free either. Treat surimi and imitation crab as a scan-the-full-list-and-ask item for both crab and fish, never as a safe substitute. It turns up in California rolls, seafood salads, and crab dips.

Restaurant stocks and seasonings. Shellfish stock, bouillabaisse and seafood soups, XO sauce, and shrimp-paste seasonings routinely carry crustacean protein, and shared fryers and woks add cross-contact. On US packaged foods crustacean shellfish must be declared, but restaurant stocks and seasonings are unlabeled, so ask. Seafood extract and undifferentiated “shellfish-derived” flavor blends can carry crab protein under non-obvious names.

A non-food source families miss. Crab-processing and live-tank seafood-market air carries aerosolized crab protein, which is a documented occupational asthma exposure for workers and a real incidental exposure for a sensitized child in that setting (Cartier 1984). Glucosamine supplements are a separate, contested question: they are often made from shellfish shells, and studies disagree on whether shellfish-allergic people can take them safely, so confirm with your allergist before introducing one.

The complete crab lexicon, the labeling-law detail, and the surimi trap in full are on where crab hides.

How exposure actually happens

The routes parents fear are not always the ones that matter, but crab has one real exception that most food allergens do not. Eating crab is the main route. Unlike peanut, breathing crab cooking vapor or processing aerosol can also cause a reaction.

Eating it (high). Swallowing crab protein is the route that causes whole-body reactions. Cooking does not help, because tropomyosin is heat-stable, so boiled, steamed, canned, and dried crab all stay allergenic.

Cooking vapor and processing aerosol (a real route for crab, unlike peanut). Vapor from boiling and steaming crab, and the aerosol in crab-processing plants and live seafood markets, is a documented route to a respiratory reaction for sensitized people; snow-crab and blue-crab processing asthma is the classic occupational version (Cartier 1984). This is categorically different from peanut, where the smell is roasting aroma and does not carry a reacting dose. For a crab-allergic child, a steamy crab boil or a busy seafood market is a real exposure to plan around, not just a smell.

Skin contact (low, higher with broken or eczematous skin). Crab on intact skin usually causes at most a local reaction. The exception is broken or eczematous skin, where the risk is higher. Raw crab handling carries more than cooked, because it adds the processing-aerosol and heat-labile-protein exposure.

A specific caution about allergy shots. A crab-allergic (tropomyosin-sensitized) child who is a candidate for house-dust-mite allergy shots (immunotherapy for asthma or hay fever) should have that discussed first, because the mite extract contains a homologous tropomyosin (Der p 10). The settled, actionable step is to test tropomyosin or Der p 10 specific IgE and talk through shellfish and snail before starting mite immunotherapy. The page does not decide whether to proceed; that is the allergist conversation.

Reading labels

This is the habit that does the most day-to-day work, and it gets fast. The words to scan for are crab, crustacean shellfish, and the species names (blue crab, snow crab, dungeness crab, king crab, mud crab). In the US, crustacean shellfish is a major allergen under FALCPA and must be declared on packaged food, and the EU and UK require it too under Regulation 1169/2011 (FALCPA; EU 1169).

A few terms are signals to slow down: surimi and imitation crab or “krab” (a fish product, crab-flavored, shared equipment), seafood extract, shellfish stock, and a generic “seafood” or “natural flavor” line that does not break out the species. The harder structural gap, and the one that catches families out, is molluscs. Clams, oysters, mussels, scallops, and squid are NOT major allergens under US law, so a US packaged label is not required to name them, and clam can sit unlabeled inside “seafood” or “natural flavoring.” The EU and UK do require molluscs to be declared. So in the US, a separate scan is needed for the molluscs that the crustacean rule does not cover.

Then there are the precautionary labels: “may contain crustaceans,” “made in a facility that also processes shellfish.” These are voluntary and unregulated in both the US and the EU, so they are not a reliable measure of how much risk is actually present. How strictly you treat them is a personal call along a spectrum, weighing a real but variable cross-contact risk against ruling out a large share of the menu. This page will not pick that threshold for you. The full label guide is on where crab hides.

Severity, and what predicts a bad reaction

The strongest population-level predictor of a severe crab reaction is sensitization to tropomyosin, the protein described above, while the minor components trend milder. A history of a previous systemic reaction is the next strongest input, along with a high crab-specific IgE and a strong skin-prick response. Crab has no single decision number, so the picture is the protein pattern plus the history, read by your allergist (Faber 2022).

Here is the part that justifies always carrying epinephrine. The size of the last reaction does not reliably predict the next one, and the cooking-vapor and processing-aerosol routes mean a serious exposure can happen without your child ever eating crab. A child whose only reaction so far was mild can still have anaphylaxis next time. That is not a reason to live in fear; it is the single reason the auto-injector travels everywhere.

Emergency preparedness

Crab anaphylaxis is treated epinephrine-first. Epinephrine is the first-line treatment for a severe reaction, not an antihistamine and not a wait-and-see. If you see anaphylaxis, you give epinephrine and then you call emergency services.

The signs that mean epinephrine now include any two body systems reacting at once (for example hives plus vomiting), or any single severe sign on its own: trouble breathing, throat tightness, a hoarse or weak cry, repetitive coughing, pale or floppy appearance, or a sense of impending doom in a child old enough to say so. When you are unsure, the guidance is to give epinephrine, because the danger of withholding it in a true reaction is far greater than the danger of giving it when it turns out you did not need to.

After giving epinephrine, call emergency services and lay the child down with legs raised, unless breathing is the main problem, in which case let them sit up. A second dose may be needed if there is no improvement in about five minutes. Every crab-allergic child should have a written anaphylaxis action plan and two epinephrine auto-injectors that go everywhere the child goes.

This section is general. Your child’s own plan is the specific one, and it is the one to follow.

When you can’t tell what’s happening

The hardest moments are usually not the clear reactions. They are the ambiguous ones. A flushed cheek after a new food. A single cough at a restaurant with a steamy seafood kitchen. A child who says their tummy hurts an hour after a snack you did not pack. Telling the start of a reaction apart from an ordinary toddler complaint is genuinely hard, and it does not resolve cleanly from across the room.

The posture that works is to treat the spectrum, not to diagnose it in the moment. Know your action plan’s override signs cold, watch whether more than one body system is involved rather than fixating on a single symptom, and accept that you will sometimes give epinephrine or call the allergist for something that turns out to be nothing. That is the system working the way it is supposed to.

The competence here builds slowly, over many ambiguous afternoons. It shows up as a shorter pause before you act.

Treatment options

Strict avoidance is the floor, and everything else is decided on top of it. Avoidance plus a written action plan plus epinephrine within reach is the standing setup for crab-allergic children, and because the other crustaceans travel with crab (see Cross-reactivity), avoidance practically extends to shrimp, lobster, and crayfish unless a supervised challenge says otherwise. Avoidance also extends to the cooking-vapor and processing-aerosol exposure, which is a real route for crab.

Crab is different from peanut and milk in one important way: there is no FDA-approved crab or shellfish oral immunotherapy. There is no crab version of a standardized desensitization drug. What exists is one approved adjunct and one investigational direction, and both are honest about what they are.

Omalizumab (an accidental-exposure adjunct, FDA-approved). Omalizumab, brand name Xolair, is an anti-IgE antibody, given as an injection, approved in February 2024 to reduce allergic reactions to accidental exposure across multiple food allergens, including shellfish, for ages 1 and up (FDA 2024). It lowers the risk from an accidental exposure; it is not a cure, it is not a desensitization, and it does not make crab safe to eat. Whether it fits a particular child is an allergist conversation, not a step the page prescribes.

Shellfish oral immunotherapy (investigational, not standard care). Shellfish OIT is being studied, but only a small minority of allergists offer shellfish or fish OIT, and there is no established crab-specific protocol, so it is not community standard of care (Allergic Living 2025). It is a trial or specialist option, not an established protocol, and the page does not describe a starting dose for a given child.

Strict avoidance remains the standard. Whether to consider any treatment at all is a conversation with your allergist.

Day-to-day living

School and day care. A crab-allergic child needs a written plan on file, epinephrine truly accessible, trained staff, and a clear routine for snacks, classroom parties, and substitute teachers. In US public schools, a 504 plan is the usual way to put that in writing. Flag the whole crustacean group, and flag steamy seafood-cooking settings, not just the obvious crab dish.

Restaurants. The risk is cross-contact, hidden crustacean in stocks and sauces, and cooking vapor more than the obvious menu item. Seafood, Asian, and shared-fryer kitchens carry higher crab risk (shellfish stock, surimi, XO sauce, seafood boils, steam). A chef card that names crab and the crustacean group plainly does more than a verbal order across a loud kitchen.

Travel. Bring more epinephrine than you think you need, carry food you trust, and look up pharmacies and emergency numbers before you land. Crab and crustacean dishes are common in coastal and high-seafood cuisines, so confirm local dishes carefully, and remember that mollusc labeling rules differ by country.

Holidays and gatherings. Seafood boils, crab dips, crab cakes, charcuterie and seafood platters, and steamy shared kitchens are the crab-dense settings. Bringing your child’s own food and being plain with hosts beats hoping a buffet is safe.

Prognosis and outgrowing

Crab is among the more persistent food allergies, and it is usually lifelong. Crustacean allergy, including crab, is rarely outgrown; seafood-allergy resolution is documented as low, which means resolution is unlikely for any one child over a typical follow-up (Ruethers 2018). No crab-specific outgrow percentage is published, so this is a qualitative low range, not a crab-specific figure. This is the inverse of the milk and egg pattern, where outgrowing is common.

There is no validated crab-specific number that predicts outgrowing the way a falling peanut Ara h 2 does; a falling tropomyosin specific IgE over time is supportive but not conclusive (Ruethers 2018). Because resolution is so uncommon, there is no routine re-test schedule the way there is for milk or egg. The reassessment cadence is individualized and your allergist’s call along that spectrum, more cautious after a severe reaction. The one definitive test of outgrowing it is a supervised oral food challenge; a falling number is encouraging but supportive, not proof (BSACI 2015).

Questions for your allergist

You do not have to walk in knowing the science. You have to walk in with the right questions, and these are them.

1. If I react to crab, how likely am I to react to shrimp, lobster, and crayfish, and should component (tropomyosin) testing guide that?
2. Is my positive crustacean blood test a real food allergy or dust-mite cross-reactivity, and does that change what my child needs to avoid?
3. How should we handle cooking-vapor and shared-kitchen or seafood-market exposure, which is a real inhalation route for crab unlike for peanut?
4. Is omalizumab relevant for accidental-exposure protection in my child’s case, and what would that involve?
5. If my child is a candidate for dust-mite allergy shots, how does the shared tropomyosin change that decision, and should we test for it first?
6. Given how rarely crab allergy is outgrown, what reassessment cadence (and whether a supervised challenge is ever appropriate) fits my child’s history?
7. What will epinephrine, and any treatment we are considering, actually cost us, and what does our insurance cover?

The frame: how to hold this

There are two worlds, and a severe food allergy moves a family from one into the other. In the recoverable world, a mistake is a lesson. A forgotten jacket is a cold afternoon. In the irrecoverable world, one wrong protein is not a lesson, because the cost of the error can be the child. When someone tells an allergy parent to relax, they are speaking from the first world to someone who has had to move to the second. They think the parent is anxious. The parent is not anxious. The parent is calibrated.

The work, then, is to sort what is on your side of the line from what is not. On your side: the labels you read, the crustacean group you keep off the plate, the epinephrine that travels with the child, the chef card that names crab plainly, the plan on file at school, the doctor you correct about the iodine myth. Not on your side: the kitchen that thickens a sauce with shellfish stock and does not say so, the steam off a crab boil at a party, the relative who thinks one bite is kindness, the manufacturer whose precautionary label is voluntary. You do the things on your side fully, and you stop apologizing for them. And you hold, without pretending otherwise, that the other side is real and partly random, and that a stacked defense reduces the risk without ever closing the gap to zero.

This page does not promise safety. It lays out the layers and names the gap, and it leaves the calibration to you and your allergist, who actually know your child.

Voices: living with crab and crustacean shellfish allergy

These are real, attributed accounts from published sources, not first-person notes from this site. They are here because crab and crustacean shellfish allergy has a distinct shape: it is heavily adult-onset, and the recurring story is a person who ate a food for decades and then, suddenly, could not. They are lived experience, not medical advice.

A self-described “beach guy” who grew up surfing the California coast and had eaten crab all his life developed a sudden, severe reaction in his forties after a dinner of fresh cooked lobster, his first time eating it. Testing confirmed he was allergic to both shellfish and finned fish, with the shellfish sensitivity much higher. His case is used to frame seafood allergy as largely an adult-onset phenomenon.

Source: Chris Oleson, in Gwen Smith, Allergic Living, 2010. https://www.allergicliving.com/2010/09/10/out-of-its-shell/ One person’s experience, not medical guidance.

A high-school teacher became allergic to shellfish in her thirties, a food she had loved and always wanted as a child. She recalls a strange sensation after eating shrimp at a party, like a shrimp tail lodged in her throat, followed by throat tightness. She kept a food log, was referred to an allergist, and crustaceans were confirmed as her allergen. The account frames how an adult-onset food allergy changes daily life overnight.

Source: Tanya Lacey, Allergic Living, 2016. https://www.allergicliving.com/2016/01/19/developing-a-food-allergy-in-adulthood/ One person’s experience, not medical guidance.

In a study of US adults and caregivers living with food allergy, an adult with shellfish allergy described how a reaction announced itself: “I noticed something was wrong because I was itching and breaking out in hives.” Shellfish was the second-most-common allergen reported in the group.

Source: Oehrlein et al., Journal of Allergy and Clinical Immunology: Global, 2025. https://pmc.ncbi.nlm.nih.gov/articles/PMC12140940/ A study quote describing what an adult shellfish reaction onset can feel like, not crab-specific testimony.

Related pages on this site

• The crustacean group and crab: cross-reactivity, the deep version
• Tropomyosin: how shellfish, dust mite, and cockroach are linked
• Where crab hides: the full label-reading guide and the surimi trap
• Shellfish and the iodine myth: why a CT scan should not be refused
• Crustacean versus mollusc: the FALCPA labeling gap
• Building a crab and crustacean 504 plan
• Restaurants and seafood kitchens with a crab-allergic child

These companion pages are being written and will be linked here as each one goes live.

Frequently asked questions

Is crab a fish?

No. Crab is a crustacean shellfish, not a fish. Finned fish (salmon, cod, tuna) carry a different main allergen, and a crab allergy does not by itself mean a fish allergy, though cross-contamination is still possible. See Cross-reactivity.

If my child is allergic to crab, do they have to avoid shrimp and lobster?

Usually yes, until an allergist says otherwise. Shrimp, lobster, and crayfish share crab’s main protein, tropomyosin, and most people allergic to one crustacean react to the others, so the whole crustacean group is treated as off the list unless a supervised challenge clears it. See Cross-reactivity.

Does a shellfish allergy mean my child can’t have a CT scan with contrast dye?

No. Shellfish allergy is not an iodine allergy, and it does not raise the risk of reacting to iodinated contrast dye more than any other allergy. Iodine is not an allergen. Tell the doctor about the shellfish allergy, but it is not a reason to refuse contrast. See Hidden sources.

Does cooking make crab safe?

No. Crab’s main protein, tropomyosin, is heat-stable and digestion-stable, so boiling, steaming, canning, and drying do not make crab safe for a crab-allergic child. Crab cooking vapor and processing aerosol can even cause a reaction on their own (Faber 2022).

Can my child outgrow a crab allergy?

Usually not. Crustacean allergy, including crab, is rarely outgrown and is usually lifelong, with only a low rate of natural resolution at the seafood-category level (Ruethers 2018). There is no crab version of the milk or egg ladder; ask your allergist about reassessment for a mild history (see Prognosis and outgrowing).

References and medical review

This page is pending independent medical review; the note at the top of the page applies until a reviewer is assigned. The references below resolve every in-body citation. The cross-reactivity, hidden-source, and myth-correction claims (the crustacean group, molluscs, the dust-mite and cockroach tropomyosin link, the shellfish-iodine and carmine corrections, the contested glucosamine question, and the crab-is-not-fish distinction) are drawn from the project’s verified cross-reactivity floor, each carrying its own source there. Where a reference has no resolvable stable identifier, it is listed bibliographically without a link rather than with an unverified URL.

1. Wang HT, Warren CM, Gupta RS, Davis CM. Prevalence and Characteristics of Shellfish Allergy in the Pediatric Population of the United States. J Allergy Clin Immunol Pract. 2020;8(4):1359-1370. https://doi.org/10.1016/j.jaip.2019.12.027
2. Gupta RS, et al. Prevalence and Severity of Food Allergies Among US Adults. JAMA Netw Open. 2019. https://doi.org/10.1001/jamanetworkopen.2018.5630
3. Faber MA, et al. Comprehending the allergen repertoire of crustaceans for precision molecular diagnosis of shellfish allergy. Allergy. 2022.
4. Ruethers T, et al. Seafood allergy: A comprehensive review of fish and shellfish allergens. Mol Immunol. 2018;100:28-57. https://doi.org/10.1016/j.molimm.2018.04.008
5. BSACI guideline for the diagnosis and management of crustacean and molluscan shellfish allergy. Clin Exp Allergy. 2015.
6. Cartier A, et al. Occupational asthma in snow crab-processing workers. J Allergy Clin Immunol. 1984. https://doi.org/10.1016/0091-6749(84)90256-2
7. US FDA. FDA approves first medication (omalizumab, Xolair) to help reduce allergic reactions to multiple foods after accidental exposure. 2024. https://www.fda.gov/news-events/press-announcements/fda-approves-first-medication-help-reduce-allergic-reactions-multiple-foods-after-accidental
8. Can You Treat Shellfish and Fish Allergies? It’s Starting to Happen. Allergic Living. 2025. https://www.allergicliving.com/2025/08/21/can-you-treat-shellfish-and-fish-allergies-its-starting-to-happen/
9. Food Allergen Labeling and Consumer Protection Act of 2004 (FALCPA); crustacean shellfish as a major allergen. https://www.fda.gov/food/nutrition-food-labeling-and-critical-foods/food-allergies
10. Regulation (EU) No 1169/2011 (Annex II allergens, crustaceans and molluscs). https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX%3A32011R1169