PHILADELPHIA — 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.

“Clinicians should assess sensitivity to nontraditional triggers in alpha-gal syndrome patients, including carrageenan,” the authors wrote. “Food and drug manufacturers should transparently disclose the presence of carrageenan.”

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.

“So you could get a nondairy ice cream because you are allergic to ice cream, and the nondairy ice cream probably has carrageenan as a thickener,” Meinholz told Medscape Medical News. She said Thermo Fisher previously had a test for carrageenan allergy, but it has since been discontinued.

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.

“Drug excipient transparency is a critical patient safety issue in the setting of alpha-gal syndrome,” Sachin A. Shah, PharmD, co-founder of Pill Clarity and professor of pharmacy at the University of the Pacific, Stockton, California, told Medscape Medical News. He would like to see manufacturers collaborating with his company “to enhance transparency and information dissemination.”

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.

“While there is some merit in creating awareness of the possibility of someone having an allergy to carrageenan, it is difficult to know if these individuals who self-report an allergy to it do not have some other underlying disorder that can explain their reactions,” Rodenas told Medscape Medical News. “It would have been interesting to know whether they had any blood testing or skin testing to confirm their symptoms are attributable to carrageenan.”

He said the findings raise questions about when it may be appropriate to test for carrageenan allergy if a reliable test can be found.

“It suggests that clinicians should be asking patients with confirmed alpha-gal whether they tolerate products containing this [additive] and educate patients about the possibility of a reaction while keeping in mind that we still have a lot to learn about alpha-gal syndrome,” Rodenas said.

The research was funded by Pill Clarity. Uchi and Shah reported being employees of Pill Clarity. Meinholz reported being a coinventor on a patent for detecting IgE antibodies to alpha-gal, serving on the advisory board for some hereditary angioedema medications, and reporting speakers’ fees from several pharmaceutical companies, which she donates to her nonprofit White Cell, Inc.; she also reported serving on the board of two alpha-gal support groups. Rodenas reported having no disclosures.

Tara Haelle is a science/health journalist based in Dallas.