Allergies to seafood — whether shellfish or fish — are among the most common food allergies in the United States, according to research.
While anecdotal reports link allergic reactions to joint pain, particularly in people with arthritis, research hasn’t shown that allergic reactions cause joint inflammation, according to the American Academy of Allergy, Asthma & Immunology.
Joint pain is implicated in mast cell activation syndrome (MCAS), however. MCAS is an immune disorder in which reactions with allergy symptoms are caused by triggers that the body doesn’t have a so-called true allergy to, according to research.
The proteins that trigger the “true” allergic reactions differ between types of seafood. As a result, you may be allergic only to shellfish or only to fish, though it’s possible to have allergies to foods in both groups, according to the Australasian Society of Clinical Immunology and Allergy (ASCIA). With MCAS, triggers are unpredictable and can change over time, according to Mast Cell Action.
Talk to your doctor about finding the cause for your allergy symptoms and joint pain.
Allergic Reactions to Seafood
Most “true” food allergies, including seafood, are considered lifelong conditions for which there are treatments but no cure, according to Cleveland Clinic. These allergies occur when your immune system mistakenly sees a protein in shellfish or fish as a threat. It creates a defense in the form of immunoglobulin E (IgE), a type of protein, antibodies that trigger an allergic reaction every time the protein is detected.
When you have an IgE antibody–triggered allergy to one crustacean, you’re likely to be allergic to other crustaceans, like crab, lobster, shrimp, and crayfish, according to the ASCIA.
But you may be able to tolerate fish or mollusks, such as clams, oysters, mussels, and scallops. And vice versa with fish and mollusks — you’re likely allergic to the other types of seafood in the same group, but not necessarily to seafood in other categories. Because seafood allergies can be severe or life-threatening, you’ll need allergy testing to confirm which types of seafood, if any, might be safe to eat.
MCAS, a form of immune system dysfunction, is considered a rare disease, though diagnosis is increasing in frequency and its actual prevalence isn’t yet known, research indicates. Experts in the field suggest that it may occur in about 17 percent of the population, according to research, however. It occurs in some people with long COVID, according to a research review.
MCAS can be hard to diagnose, even if your doctor understands the condition, says Kara Wada, MD, an allergist and immunologist in Columbus, Ohio. Testing is limited in scope, and the chemicals being tested for are often broken down quickly by the body, making it hard to get accurate results.
Mast cells are white blood cells that are also involved in “true” allergic reactions involving IgE antibodies. They release histamine and many other chemicals to defend against the perceived threat, says Lisa Klimas, a microbiologist and molecular biologist in Boston who researches mast cell disorders.
The symptoms of reactions to seafood caused by MCAS can be the same as reactions that are triggered by IgE antibodies. They can include swelling, hives, flushing, tachycardia, anxiety, cognitive issues, vomiting, and diarrhea. Anaphylaxis is common and can be life-threatening in both allergies and MCAS. It can include swelling of the tongue, throat, and airway; wheezing; and difficulty talking.
Because the immune system is dysregulated in MCAS, mast cells activate unpredictably in reaction to harmless triggers, which can include foods, fragrances, stress, chemicals, medications, physical exercise, and even changes in temperature. This can make it difficult to identify triggers. And unlike most IgE antibody-triggered allergic reactions, MCAS reactions can be delayed by hours or days, says Dr. Wada. With MCAS, triggers are inconsistent — something that never triggered a reaction may do so, and things that triggered past reactions may suddenly stop.
MCAS reactions typically involve symptoms in two or more organ systems at the same time. Additionally, MCAS is known to follow a relapsing-remitting cycle, which means there will be episodic flare-ups as well as times with few (or no) symptoms, according to research.
Joint Pain
Joint pain is not considered a common symptom of a seafood allergy, according to the ASCIA. While there is a belief that allergic reactions cause or worsen inflammation in rheumatoid arthritis, leading to joint pain, according to the Association of UK Dietitians, there’s no evidence to support this theory.
Joint pain is a common symptom of MCAS, however. According to research, “[b]one, joint, and muscle pain are reported by many patients as a daily symptom that significantly interrupts their quality of life.”
Avoidance
The most effective way to treat a seafood allergy that causes joint pain is to identify which type (or types) of seafood you’re allergic to and avoid it, according to Cleveland Clinic. Avoidance is easy at home, but can be more challenging when you’re eating food you didn’t make yourself, according to the ASCIA.
Watch for displays of food where allergens may have been in contact with other foods, and check the ingredients list on prepackaged foods. When eating out, ask about whether seafood ingredients have been used as a base in soups or sauces, or if fried foods have been cooked in the same oil as allergens.
With MCAS, it can be harder to avoid triggers, due to the unpredictability of reactions. But often, a trigger will consistently cause reactions for a period of time, and you should aim to minimize exposure, says Wada. Some people with MCAS opt to consume a low-histamine diet to reduce symptoms, according to Mast Cell Action.
Foods that are high in histamine include seafood, particularly seafood that’s been improperly stored, according to the British Society for Allergy & Clinical Immunology. Often, after a period of avoidance, people with MCAS are able to reintroduce certain food triggers, even those that are high in histamine. This isn’t always possible, however, Klimas says. It can help to work with a registered dietitian and your doctor to reintroduce foods safely.
Treatment
If you ingest seafood by accident, you may be able to treat mild IgE antibody–triggered allergic reactions symptoms with an antihistamine, according to Cleveland Clinic. You can treat any joint pain with over-the-counter pain relievers to reduce the swelling and pain, according to the University of Pittsburgh Medical Center.
Steroids are sometimes used to treat inflammation caused by more severe allergic reactions. Because IgE allergies can quickly escalate to anaphylaxis, which can be life-threatening, your doctor will prescribe you an epinephrine auto-injector (EpiPen, Auvi-Q) and give you instructions on how to use it as soon as you first experience symptoms of a severe reaction.
With MCAS, treatment is complex and varies by individual. People typically take medications such as antihistamines daily, and during a reaction they might add an additional antihistamine, such as diphenhydramine (Benadryl), Klimas says. A type of NSAID called a COX-2 inhibitor celecoxib (Celebrex) may be prescribed for joint pain. Mast Cell Action notes, however, that other medications used in MCAS treatment can also treat pain by blocking or preventing the release of inflammatory chemicals.
Like IgE-antibody allergic reactions, MCAS reactions are sometimes treated with steroids. MCAS reactions can be life-threatening and quickly progress to anaphylaxis the same way IgE-triggered allergic reactions can; the treatment is also injection of epinephrine using an auto-injector pen.
A number of other medications may be used to prevent reactions or treat the symptoms of excessive mast cell activation. Commonly-used medications include mast cell stabilizers such as cromolyn sodium (Gastrocrom); systemic biologic medications like omalizumab (Xolair); and medications that block allergic symptoms caused by chemicals called leukotrienes, including montelukast (Singulair), among others.
Talk to your doctor about testing if you’re not sure what kind of reactions you’re having, or to determine whether seafood may be a trigger.
