Hyaluronic acid is generally well tolerated as long as it has been made vegan and does not contain any foreign animal proteins. Sensitive skin can react to this with adverse reactions. You also don't have to worry about hyaluronic acid leaving an air-impermeable film on the skin. The high-molecular hyaluronic acid that remains on the surface of the skin does not hermetically seal the skin. Rather, it strengthens the skin's barrier function, prevents moisture loss while protecting against free radicals, and allows the skin to breathe. This helps prevent bacteria from multiplying and increasing irritation and inflammation of the skin.