Shellfish can cause severe allergic reactions (such as anaphylaxis). Therefore it is advised that people with shellfish allergy have quick access to an epinephrine auto-injector (such as an EpiPen®, Auvi-Q® or Twinject®) at all times. This allergy usually is lifelong. Approximately 60 percent of people with shellfish allergy experienced their first allergic reaction as adults. Shrimp, crab and lobster cause most shellfish allergies. Finned fish and shellfish do not come from related families of foods, so being allergic to one does not necessarily mean that you must avoid both. To prevent a reaction, strict avoidance of shellfish and shellfish products is essential. Always read ingredient labels to identify shellfish ingredients.
There are two kinds of shellfish: crustacea (such as shrimp, crab and lobster) and mollusks (such as clams, mussels, oysters and scallops). Reactions to crustacean shellfish tend to be particularly severe. If you are allergic to one group of shellfish, you might be able to eat some varieties from the other group. However, since most people who are allergic to one kind of shellfish usually are allergic to other types, allergists usually advise their patients to avoid all varieties. If you have been diagnosed with a shellfish allergy, do not eat any shellfish without first consulting your doctor.
To prevent a reaction, strict avoidance of shellfish and shellfish products is essential. Always read ingredient labels to identify shellfish ingredients. In addition, avoid touching shellfish, going to the fish market, and being in an area where shellfish are being cooked (the protein in the steam may present a risk).
The federal Food Allergen Labeling and Consumer Protection Act (FALCPA) requires that all packaged food products sold in the U.S. that contain shellfish as an ingredient must list the specific shellfish used on the label.
Read all product labels carefully before purchasing and consuming any item. Ingredients in packaged food products may change without warning, so check ingredient statements carefully every time you shop. If you have questions, call the manufacturer.
As of this time, the use of advisory labels (such as “May Contain”) on packaged foods is voluntary, and there are no guidelines for their use. However, the FDA has begun to develop a long-term strategy to help manufacturers use these statements in a clear and consistent manner, so that food-allergic consumers and their caregivers can be informed as to the potential presence of major allergens.
Avoid foods that contain shellfish or any of these ingredients:
- Crawfish (crawdad, crayfish, ecrevisse)
- Lobster (langouste, langoustine, Moreton bay bugs, scampi, tomalley)
- Shrimp (crevette, scampi)
- It is important to note that mollusks are not considered major allergens under FALCPA and may not be fully disclosed on a product label.
Your doctor may advise you to avoid mollusks or these ingredients:
- Clams (cherrystone, geoduck, littleneck, pismo, quahog)
- Limpet (lapas, opihi)
- Sea cucumber
- Sea urchin
- Snails (escargot)
- Squid (calamari)
- Whelk (Turban shell)
Shellfish are sometimes found in the following:
- Cuttlefish ink
- Fish stock
- Seafood flavoring (e.g., crab or clam extract)
Keep the following in mind:
- If you have seafood allergy, avoid seafood restaurants. Even if you order a non-seafood item off of the menu, cross-contact is possible.
- Asian restaurants often serve dishes that use fish sauce as a flavoring base. Exercise caution or avoid eating there altogether.
- Shellfish protein can become airborne in the steam released during cooking and may be a risk. Stay away from cooking areas.
- Carrageenan, or "Irish moss,” is not shellfish. It is a red marine algae that is used in a wide variety of foods, particularly dairy foods, as an emulsifier, stabilizer, and thickener. It appears safe for most individuals with food allergies.
- Allergy to iodine, allergy to radiocontrast material (used in some radiographic procedures), and to shellfish are not related. If you have an allergy to shellfish, you do not need to worry about cross reactions with radiocontrast material or iodine.
Download our PDF on how to read a label for a shellfish-free diet.
1Sicherer SH, Munoz-Furlong A, Sampson HA. Prevalence of seafood allergy in the United States determined by a random telephone survey. J Allergy Clin Immunol 2004; 114(1):159-65.