Shellfish allergy is one of the most common food allergies in adults, and unlike some childhood allergies, it rarely goes away. The tricky part isn't avoiding an obvious shrimp cocktail — it's catching the oyster sauce in a stir-fry, the crab extract in a bisque, or the shrimp paste buried in a curry. This complete shellfish allergy list covers every species to avoid and every hidden ingredient to watch for when you're eating out.
Two Categories: Crustaceans and Mollusks
Shellfish fall into two biological groups. Some people react to both. Others react to only one. Knowing which group triggers your allergy helps you navigate menus more precisely.
Crustaceans (Most Common Triggers)
Crustaceans cause the majority of shellfish allergy reactions. If you're allergic to one crustacean, you're likely allergic to others in this group.
- Shrimp (also called prawns) — the most common trigger worldwide
- Crab — all varieties including king crab, snow crab, Dungeness, blue crab, and soft-shell crab
- Lobster — includes Maine lobster, rock lobster, and langoustine
- Crawfish (also called crayfish or crawdads)
- Krill — used in some omega-3 supplements and fish feed
Mollusks
Mollusk allergy is less common but still serious. Cross-reactivity between mollusks and crustaceans is not guaranteed — some people tolerate mollusks fine — but many allergists recommend avoiding both groups.
- Clams — includes littleneck, Manila, razor clams, and geoduck
- Mussels — common in pasta dishes, paella, and bouillabaisse
- Oysters — raw bars, Rockefeller preparations, and oyster sauce
- Scallops — sea scallops and bay scallops
- Squid (calamari) — fried calamari is a common appetizer
- Octopus — grilled, in poke bowls, and in Mediterranean dishes
- Snails (escargot) — classic French preparation with garlic butter
- Abalone — more common in Asian cuisine
Hidden Shellfish Ingredients in Restaurant Food
This is where most accidental exposures happen. These ingredients contain shellfish protein but don't always announce themselves on a menu.
Oyster Sauce
Found in countless Chinese, Thai, and Vietnamese dishes. It's in stir-fries, fried rice, chow mein, pad Thai variations, and many brown sauces. It's made from oyster extract and is a staple condiment in Asian cooking. Always ask if a dish contains oyster sauce — it won't be listed by name on most menus.
Shrimp Paste
A fermented condiment used heavily in Southeast Asian cuisine. It appears in Thai curries (especially red and green curry paste), Malaysian laksa, Indonesian sambal, and some Filipino dishes. The menu will say "curry" — it won't say "contains shrimp paste."
Fish Sauce
While technically made from fish (usually anchovies), some fish sauces contain shrimp or other shellfish. It's used widely in Thai, Vietnamese, and Filipino cooking. If you have a severe shellfish allergy, ask about the specific brand used.
Surimi (Imitation Crab)
Surimi is processed fish paste flavored and shaped to resemble crab. It usually doesn't contain actual crab — but some brands add crab extract for flavor, and it's often processed on shared equipment. Found in California rolls, seafood salads, crab rangoon, and crab cakes at lower-end restaurants.
Glucosamine Supplements
Often derived from shrimp, crab, or lobster shells. If you take joint supplements, check the source. Plant-based glucosamine alternatives exist.
Bouillabaisse, Cioppino, and Seafood Stocks
These stews and stocks are shellfish-heavy by definition, but the risk extends beyond the stew itself. Some restaurants use seafood stock as a base for other soups, risottos, or sauces that don't have "seafood" in the name. Ask whether the kitchen uses shellfish-based stock in any preparation.
Caesar Dressing
Traditional Caesar dressing contains anchovies (fish, not shellfish), but some restaurant versions add Worcestershire sauce that may contain shellfish, or the dressing is prepared in shared equipment. Low risk, but worth mentioning to your server if your allergy is severe.
Cross-Contamination Risks at Restaurants
Even if your dish contains no shellfish ingredients, cross-contamination in the kitchen can cause reactions.
- Shared fryers — Fried shrimp and fried chicken often share the same oil. Ask if the restaurant uses a dedicated fryer for non-seafood items.
- Shared grills and cooking surfaces — A burger cooked on the same flat-top where shrimp was just grilled picks up residual protein.
- Steam and airborne particles — In open kitchens or seafood-heavy restaurants, aerosolized shellfish protein from boiling or steaming can trigger reactions in highly sensitive individuals.
- Shared utensils and prep areas — Tongs, cutting boards, and countertops used for shellfish prep can transfer allergens.
How to Order Safely at Restaurants
- Tell your server and the kitchen — Don't just scan the menu yourself. Mention your allergy before ordering so the kitchen can take precautions.
- Ask about sauces, stocks, and shared cooking oil — The three most common hidden exposure points.
- Avoid buffets and family-style service — Shared serving utensils make cross-contamination nearly impossible to prevent.
- Carry epinephrine — If you have a prescribed EpiPen, bring it. Shellfish allergy reactions can escalate quickly from mild to anaphylactic.
- Choose restaurants strategically — Steakhouses and farm-to-table spots typically have fewer shellfish cross-contamination risks than seafood restaurants or Asian fusion kitchens.
Shellfish vs. Fish: They're Different Allergies
A shellfish allergy does not mean you're allergic to fish. Shellfish (shrimp, crab, lobster) and fish (salmon, tuna, cod) are biologically unrelated. Many people with shellfish allergies eat fish safely. However, cross-contamination is common in kitchens that handle both — so the preparation environment matters even if the ingredient itself is safe for you.
Quick Reference: The Complete Shellfish Allergy Avoid List
Crustaceans: shrimp, prawns, crab (all types), lobster, langoustine, crawfish, krill
Mollusks: clams, mussels, oysters, scallops, squid (calamari), octopus, snails (escargot), abalone
Hidden ingredients: oyster sauce, shrimp paste, fish sauce (some brands), surimi (some brands), shellfish-based stock, glucosamine from shellfish
High-risk cuisines: Chinese, Thai, Vietnamese, Japanese, Korean, Malaysian, French seafood, Mediterranean coastal
DinePick is building tools to automatically flag shellfish ingredients and hidden shellfish sources on restaurant menus — so you can scan before you order instead of hoping your server catches everything.