Glucosamine and Shellfish (Like Shrimp) Allergy

Is Glucosamine Safe if You Have a Shellfish Allergy?

glucosamine tablets on shells
Can you take glucosamine if you have a shellfish allergy?. Photo©Farion_O

Can people who are allergic to shellfish, such as shrimp, take glucosamine? Does glucosamine ever cause serious allergic reactions in shellfish allergic people?

What Is Glucosamine?

Glucosamine is a natural substance that plays an important role in the formation and repair of healthy cartilage. It is a popular dietary supplement, often taken in combination with chondroitin sulfate, and is used for the treatment of osteoarthritis among other conditions.

Glucosamine as a Dietary Supplement

Gucosamine is available alone, combined with chondroitin sulfate, or in combination with several other compounds as a nutritional supplement. It is usually marketed for people with arthritis or other ailments. Based on results in what is known as the GAIT trial, the American College of Rheumatology has provided guidelines for its use.

Unfortunately, nutritional supplements are not subject to the same stringent guidelines that prescription drugs are, and different formulations can vary considerably. There are three primary forms which are available, including glucosamine sulfate, glucosamine hydrochloride, and N-acetyl-glucosamine, but what is listed on the bottle does not necessarily correlate with what's inside. Herbal studies have found that the amount of active ingredient in these supplements can vary from zero to 100 percent of that listed.

Glucosamine and Shellfish Allergies

Glucosamine is often made from the shells of shrimp, crab and lobster, and therefore people with shellfish allergy have often been advised against taking this supplement.

In some countries, synthetic glucosamine is available. Chondroitin sulfate is made from cattle or shark cartilage.

According to the American Academy of Allergy, Asthma, and Immunology it is a misconception that people who have shellfish allergies cannot take glucosamine. Is there any research to show there is a concern?

How can you make your own educated decision?

Is Glucosamine Safe With Shellfish Allergies?

There is currently little evidence that glucosamine contains shellfish proteins, the part of shellfish responsible for causing symptoms of food allergy.

There has been one report of a severe immediate hypersensitivty reaction precipitated by glucosamine in a shellfish allergic person in 1999. There have also been reported cases that have suggested a link between products containing glucosamine and chondroitin and asthma exacerbations (asthma "attacks.")

A 2006 study looked at 15 people confirmed to be shrimp allergic by by both skin tests and shrimp specific IgE assay (blood tests). All 15 tolerate a supplement of the shrimp-derived glucosamine-chondroitin (1500mg of glucosamine) both initially and after 24 hours (to rule out a delayed reaction.)

Two other small studies, with a total of 22 people, showed that people with shellfish allergy could take glucosamine without allergic reactions.

These studies suggest that glucosamine does not contain shellfish proteins, and can be safely taken by people with shellfish allergy. However, given the small number of people studied to date, it would be prudent for people with shellfish allergy to check with their physician prior to taking glucosamine.

A referral to an allergist may be warranted, with the consideration of a medically supervised oral challenge to glucosamine.

What Foods Are Considered Shellfish?

There are two main categories of shellfish invertebrates. These include crustaceans and mollusks.

  • Crustaceans include shrimp/prawns, lobster, crab, crayfish (crawfish) yabbies, and sea urchin.
  • Molluscs include oysters, mussels, clams (quahogs), limpets, octopus, snails (escargot), squid (calamari), cuttlefish, sea cucumber, abalone, sea slugs, whelks, cockles, and surimi (imitation shellfish found in sushi)

Foods Which May Contain Shellfish

If you are allergic to shellfish, you will need to be careful not only to avoid shellfish directly, but know how to check ingredients to make sure that shellfish components aren't used. Make sure to review these ​ingredients that may contain shellfish. In addition, here are some tips for eating at restaurants with seafood allergies. While it's not a problem for the majority of people, pet foods often contain shellfish. If you are very allergic, you may wish to have someone else feed the cat his favorite seafood medley.

Seafood Allergy

Seafood allergy is one of the allergies that is more common in adults than children, and it is the most common food allergy found in adults.

Within a category (either crustaceans or mollusks) if you react to one food, you are likely to be allergic to others as well. For example, if you are allergic to clams you will likely be allergic to mussels as well.

Allergy vs Food Intolerance to Shellfish

It is very important to distinguish whether you have a true allergy to shellfish or, instead, a food intolerance. The difference between these reactions determines the type of symptoms you may experience. With a food intolerance you may feel very ill, and medical attention may be needed due to dehydration from vomiting or diarrhea. In contrast, with an allergy you could go into anaphyactic shock, a medical emergency which can be fatal without treatment.

Shellfish Allergy and Food Dyes

Though concern has been raised in the past over a relationship between shellfish allergy and reactions to food dyes and radiocontrast dye, it's currently thought that it's okay to have radiocontrast dye unless you are specifically allergic to the dye itself.

Glucosamine Allergy

Aside from the relationship with shellfish, some people may have an allergy to glucosamine. In particular, glucosamine hypersensitivity has been found in people with chronic liver disease.

Bottom Line on Glucosamine and Allergy

Though it appears that most people with a shellfish allergy could tolerate glucosamine, if you have a severe shellfish allergy you should talk to your allergist before considering a supplement with this compound.


Gray, J., Hutcheson, P., and R. Slavin. Is Glucosamine Safe in Patients with Seafood Allergy?. Journal of Allergy and Clinical Immunology. 2004. 114(2):459-60.

Matheu, V., Gracia Bara, M., Pelta, R., Vivas, E., and M. Rubio. Immediate-Hypersensitivity Reaction to Glucosamine Sulfate. Allergy. 1999. 54(6):643.

U.S. National Library of Medicine. Medline Plus. Glucosamine Sulfate. Updated 04/22/16.

Villacis, J., Rice, T., Bucci, L., El-Dahr, J., Wild, L., Demerell, D., Soteres, D., and S. Lehrer. Do Shrimp-Allergic Individuals Tolerate Shrimp-Derived Glucosamine?. Clinical and Experimental Allergy. 2006. 36(11):1457-61.

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