Researchers tested iota-carrageenan (a thickener used in cosmetics and food) applied directly into the nose and inhaled in animals over 7-28 days. The carrageenan didn't penetrate the nasal tissue or enter the bloodstream, caused no irritation or toxicity, and didn't trigger immune responses—suggesting it's safe for topical nasal use at 0.12% concentration.

Scientists applied 0.12% iota-carrageenan intranasally to rabbits for up to 28 days and gave nebulized doses to rats for 7 days. They also ran lab tests to check for inflammation and measured whether the ingredient could actually cross into the bloodstream.

Funding not disclosed in abstract