Homosalate

Homosalate is an organic UVB filter typically used around 5–15% in sunscreens; at these leave-on concentrations it is generally well tolerated but can sting or cause irritant dermatitis in reactive or eczematous skin, especially on compromised barriers. Clinical patch-test data show low rates of true allergy, yet irritation and eye-area stinging are reported in real-world use, so I rate it as mild rather than gentle for highly sensitive populations. Safety Notes: In consumer sunscreen products, homosalate is commonly used as an organic UVB filter at low supporting levels (~0.1–1%) in multi-filter formulas and as a primary filter in the mid-to-high single digits. The highest concentrations observed in over-the-counter, general-public leave-on sunscreens in the US reach 10%, consistent with FDA OTC monograph limits; EU cosmetics rules no longer permit homosalate in sunscreen products, so current EU-market products are effectively 0%. Rinse-off products rarely use it, and when present it is typically at trace/low levels for incidental UV protection claims rather than primary SPF contribution.