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Sunscreen filters

Homosalate

Also listed as HMS, homomenthyl salicylate

A weak UVB filter used in high amounts in many US sunscreens. Well absorbed and weakly hormone-active in lab tests; the EU now limits it to 7.34% in face products only.

Moderate evidenceTypical strength: Up to 15% (US); EU maximum 7.34%, face products only

What it is

Homosalate absorbs UVB (peak around 306 nm) and helps dissolve other filters. Because it is weak, US formulas may use a lot of it (the US allows up to 15%).

It is one of the more absorbed filters (blood levels around 14-23 ng/mL in the FDA trial) and showed weak oestrogen-like activity in cell studies. After its safety committee's review, the EU cut its maximum to 7.34% and only in face products (not body products or propellant sprays), with the change fully in force from July 2025.

How strong is the evidence?

Moderate evidence

UVB absorption is well established, but homosalate contributes modestly to protection per percent used. Endocrine concerns come from cell and animal studies; there are no human studies showing hormonal effects from sunscreen use. The EU restriction is precautionary, based on margin-of-safety calculations. FDA lists it as needing more data.

What it's used for, checked

Adds UVB protection

Holds up

A supporting filter; needs partners for broad-spectrum protection.

Disrupts hormones in people

Unproven

Weak activity in cell studies only; no human evidence at sunscreen exposures.

Works well with

  • avobenzone
  • octisalate

Who should be careful

  • If you want to limit absorbed filters (for example during pregnancy or for young children), choose mineral filters or the newer large-molecule filters. This is a precaution, not a response to proven harm.
  • Do not skip sun protection over absorption worries; UV damage is the proven harm.

The studies

Every citation is checked against its PubMed record.

  1. Effect of Sunscreen Application on Plasma Concentration of Sunscreen Active Ingredients: A Randomized Clinical Trial.
    Matta MK, Florian J, Zusterzeel R, et al. · JAMA · 2020 · RCT (pharmacokinetic)

    48 healthy adults applied one of four sunscreens to 75% of the body, up to 4 times a day for 4 days. Avobenzone, oxybenzone, octocrylene, homosalate, octisalate and octinoxate all exceeded the FDA's 0.5 ng/mL screening threshold after a single application; oxybenzone reached about 258 ng/mL from lotion. The authors state this does not mean people should stop using sunscreen.

  2. In vitro and in vivo estrogenicity of UV screens.
    Schlumpf M, Cotton B, Conscience M, et al. · Environ Health Perspect · 2001 · Laboratory and animal study

    Oxybenzone, homosalate, octinoxate and two other filters made breast-cancer cells proliferate in a dish; in immature rats, octinoxate and oxybenzone raised uterine weight only at very high oral doses (around 935 and 1,525 mg/kg/day). Avobenzone was inactive. Hazard screening, not evidence of effects at human exposure.