Non-clinical safety evaluation of…al iota-carrageenan.

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.