Tick bites from the lone star tick are increasingly resulting in the alpha-gal syndrome in the United States. This syndrome results in an intense delayed allergic response to red meat (beef, pork, and lamb), dairy products, and gelatin. Researchers have now found another common food ingredient that may cause an allergic response in those with the syndrome: carrageenan.
Carrageenan is derived from seaweed and is a commonly used emulsifier in foods and an ingredient in medications. A recent study of 562 individuals with self-reported alpha-gal syndrome found that about 11% reported an allergic response to carrageenan.
Following up on this in larger groups of people (how pervasive is carrageenan allergy in alpha-gal syndrome?) will be interesting. Many drugs don't report ingredient lists, and how many people actually read food ingredient lists? Unfortunately, someone trying to avoid dairy products due to alpha-gal syndrome may instead eat non-dairy ice cream - which contains carrageenan (as a thickener)!
From Medscape: Carrageenan: A Potential Allergen for Patients With Alpha-Gal Syndrome
Carrageenan is the second most commonly self-reported allergy by individuals with alpha-gal syndrome, surpassing nearly all other alpha-gal-containing food allergens, according to a research poster presented at the American Academy of Allergy, Asthma & Immunology (AAAAI) 2026 Annual Meeting.
Up to 1 in 10 people with alpha-gal syndrome who sought information about ingredients in medications reported having an allergy to carrageenan. Carrageenan is a polysaccharide derived from red seaweed that is widely used as an emulsifier in food and as an ingredient in various medications. Despite not being from an animal source, carrageenan has the alpha-gal epitope.
“Carrageenan is not routinely discussed during alpha-gal syndrome counseling despite widespread use in foods and medications, and ingredient disclosure remains inconsistent, particularly for pharmaceutical excipients,” Jasmine Uchi, PharmD, director of medical affairs and operations at Pill Clarity, and her colleagues reported. Pill Clarity is a company operated by VeganMed, Inc., that aims to identify medications and supplements that do not contain animal-derived ingredients or certain allergens.
In a separate poster also authored by Uchi, the researchers identified several discrepancies between drug manufacturers’ disclosure of carrageenan as an ingredient in one of their medications and carrageenan’s inclusion in that drug’s ingredient list in the DailyMed FDA database.
The researchers conducted a retrospective analysis of unique inquiries submitted to Pill Clarity in June and July 2025 from individuals who identified themselves as having alpha-gal syndrome. The authors calculated how many individuals identified themselves as having an allergy to carrageenan, milk, eggs, fish, crustacean shellfish, tree nuts, peanuts, wheat, soybeans, sesame, gluten, an unspecified drug, or other substances.
Among 562 unique patients with self-reported alpha-gal syndrome, the most commonly reported allergy was to dairy and milk proteins, reported by 14.2% of patients. The second most commonly self-reported allergy was to carrageenan, reported by 10.9% of patients, followed by gluten (7.7%). The frequency of self-reported allergy was lower for tree nuts (3.7%), shellfish (2.9%), soy (2.5%), eggs (2.5%), peanuts (1.6%), and wheat (1.4%). In addition, 11.4% of patients reported an unspecific drug allergy.
The challenge is that many alpha-gal patients may not be aware of carrageenan or that it could potentially be an allergen for them, said Tina Merritt Meinholz, MD, allergist and immunologist at Allergy & Asthma Clinic of Northwest Arkansas in Bentonville, Arkansas, and one of the study’s co-authors.
Meinholz said carrageenan needs to be considered as a potential ingredient and allergen if patients react to a drug but don’t appear to have any allergies to other ingredients in that drug. One example is dabigatran, a common generic blood thinner; some versions of dabigatran contain carrageenan, while others do not.
Mario Rodenas, MD, associate professor of medicine and director of the clinical elective in allergy and immunology for medical students at Yale University, New Haven, Connecticut, urged some caution in interpreting the results of the study given that the allergies were self-reported and no test results were presented — a limitation noted by the authors as well.