Homosalate

Organic UV Filter (UVB)

Also known as: Homomenthyl Salicylate, HMS, 3,3,5-Trimethylcyclohexyl Salicylate

Description

Homosalate is a salicylate-based organic UVB filter that absorbs UV radiation in the 295–315 nm range, with peak absorption at approximately 306 nm. FDA-approved at concentrations up to 15%, it is one of the most commonly used UV filters for boosting SPF in combination sunscreen formulations. Homosalate has a well-established safety record with decades of use. It has lower molar absorptivity compared to cinnamate filters, so it is typically used at higher concentrations or in combination with other UV filters. Its excellent oil solubility, low photo-irritation potential, and cosmetically elegant feel make it a popular choice in daily-wear sunscreens. The SCCS (Scientific Committee on Consumer Safety) has recommended a maximum concentration of 7.34% in the EU based on systemic absorption data. [Burnett 2011]

Mechanism of Action

Homosalate absorbs UVB photons through its salicylate chromophore, which undergoes excited-state intramolecular proton transfer (ESIPT) between the phenolic hydroxyl and the ester carbonyl group. This rapid non-radiative decay pathway converts absorbed UV energy into thermal energy (heat), providing photoprotection without generating significant reactive intermediates. Salicylate UV filters are among the most photostable organic filters due to this efficient energy dissipation mechanism. Homosalate does not significantly degrade under UV exposure, though it has weak photostabilizing effects on other UV filters. [Shaath 2010]

Indications

  • UVB photoprotection [Burnett]
  • SPF boosting in combination formulations [Janjua]
  • Sunburn prevention
  • Daily photoprotection

Available Concentrations

5%10%15% (FDA maximum)

Side Effects

  • Contact dermatitis (rare) [Janjua]
  • Mild irritation in very sensitive skin
  • Potential weak estrogenic/anti-androgenic activity (in vitro, clinical significance debated)
  • Systemic absorption detected in pharmacokinetic studies

Contraindications

  • Known hypersensitivity to homosalate or salicylate derivatives
  • Caution in patients with aspirin/salicylate allergy (cross-reactivity theoretically possible but not well-documented)

Pregnancy Category

Not formally classified (topical use generally considered low risk)

Found In

Cosmetics containing Homosalate

Aqualogica Glow+ Dewy Sunscreen SPF 50 PA++++AqualogicaJoy Revivify Vitamin C Sunscreen SPF 50 PA++++Joy Revivify (RSH Global)Neutrogena Ultra Sheer Dry-Touch Sunblock SPF 50+ PA+++Neutrogena (Johnson & Johnson)Pilgrim Vitamin C Sunscreen SPF 50 PA++++Pilgrim

Related Conditions

Photoaging UVB filter — absorbs UVB radiation (295–315 nm), commonly used to boost SPF and prevent cumulative photodamage

References

  1. Burnett ME, Wang SQ. "Current sunscreen controversies: a critical review." Photodermatol Photoimmunol Photomed, 2011. doi:10.1111/j.1600-0781.2011.00557.x
  2. Janjua NR, Mogensen B, Andersson AM, et al. "Systemic absorption of the sunscreens benzophenone-3, octyl-methoxycinnamate, and 3-(4-methyl-benzylidene) camphor after whole-body topical application and reproductive hormone levels in humans." J Invest Dermatol, 2004. doi:10.1111/j.0022-202X.2004.22725.x
  3. Shaath NA. "Ultraviolet filters." Photochem Photobiol Sci, 2010. doi:10.1039/b9pp00174c

Limitations

This page provides a general overview of Homosalate in dermatology. It does not cover every possible use, formulation, or interaction. Individual responses to compounds vary — what works for one person may not work for another. Always consult a qualified dermatologist before starting or changing any treatment.