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Sunscreen filters

Bisoctrizole

Also listed as methylene bis-benzotriazolyl tetramethylbutylphenol, MBBT, Tinosorb M

A particle-form organic filter covering UVB through long-wave UVA. Photostable and barely absorbed; allowed in the EU at 10% but not approved in the US.

Strong evidenceTypical strength: Up to 10% (EU); not permitted as a US sunscreen active

What it is

Bisoctrizole is an organic filter made as microfine particles dispersed in the water phase, so, like the mineral filters, it both absorbs and scatters UV. It covers UVB through UVA1 (peaks near 305 and 360 nm) and is very photostable.

It is permitted in the EU (up to 10%, including a nano form, which is not allowed in sprays), Australia and much of Asia. It is not an approved sunscreen active in the US, so products containing it here are generally imported formulas.

How strong is the evidence?

Strong evidence

Its broad-spectrum absorption and stability are established in formulation and SPF/UVA testing. Toxicology reviews found no genotoxicity or reproductive toxicity and low absorption, with a wide margin of safety at 10%. Clinical outcome trials exist for sunscreens in general, not for this filter specifically.

What it's used for, checked

Broad-spectrum protection including UVA1

Holds up

One of the few single filters reaching long-wave UVA.

Low absorption into the body

Holds up

Large molecule in particle form; dermal absorption is low in the safety data.

Works well with

  • bemotrizinol
  • zinc-oxide

Who should be careful

  • Allergy is rare; most reported cases traced to decyl glucoside, the surfactant used to disperse the particles, rather than to the filter itself. If you react, ask for patch testing to both.
  • Imported sunscreens are not reviewed by the FDA; buy from sources that sell genuine stock.

The studies

Every citation is checked against its PubMed record.

  1. Safety assessment of methylene bis-benzotriazolyl tetramethylbutylphenol, a UV filter in cosmetics.
    Kim M, Kim SB, Lee JD, et al. · Toxicol Res · 2026 · Toxicological review / risk assessment

    Reviewing animal and lab data, the filter showed no genotoxicity, no reproductive or developmental effects up to 1,000 mg/kg/day, and no skin sensitisation at 30%. The calculated margin of safety exceeded 100 at 10% use in all cosmetics.