Tinosorb M (Bisoctrizole)
A hybrid filter that both absorbs and reflects UV — broad-spectrum, photostable, low white cast, and very low allergy
INCIMethylene Bis-Benzotriazolyl Tetramethylbutylphenol
- Category
- Sunscreen / UV Filter
- Risk level
- low
- Hybrid filter
- A microparticle that both absorbs (like a chemical filter) and reflects/scatters (like a mineral) UV
- Broad-spectrum + photostable
- Covers UVB and UVA1/UVA2 (~280–400 nm) and helps stabilise other filters
- Availability
- Approved across the EU/Asia/Australia; NOT FDA-approved in the US
- Tolerability
- Large microparticle, minimal penetration, allergy essentially unheard of; little white cast
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Commonly found in
Possible reactions
- Allergic reactions extremely rare
- No photodegradation
- No sun sensitivity
- Minimal systemic absorption
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What is Tinosorb M?
Tinosorb M (INCI: Methylene Bis-Benzotriazolyl Tetramethylbutylphenol; also bisoctrizole) is an unusually clever UV filter because it works by two mechanisms at once: formulated as microparticles, it absorbs UV like a chemical filter and reflects/scatters it like a mineral filter. That hybrid action makes it highly effective across the full UV spectrum and very stable in sunlight.
Developed by BASF and EU-approved in 2000, it's a photostable, broad-spectrum filter (UVB + UVA1/UVA2). It's one of the "Tinosorb twins" with Tinosorb S, and premium European sunscreens often combine the two. Like the other modern filters, it is not FDA-approved in the US.
Why it's so well tolerated
Tinosorb M is a very large molecule (~659 Da), formulated as microparticles that don't penetrate intact skin — so systemic absorption is minimal and contact dermatitis is essentially unheard of. The EU has confirmed it safe up to 10%.
- Hybrid protection — a "belt-and-braces" absorb-plus-reflect approach.
- Photostable + stabiliser — doesn't degrade, and helps hold other filters together.
- Low white cast — its physical component is engineered to be near-invisible.
- Sensitive/children — a common choice for gentle and kids' formulas.
How to use it well
- Look for it by name — Methylene Bis-Benzotriazolyl Tetramethylbutylphenol / Bisoctrizole.
- Combine with Tinosorb S for the most complete coverage.
- Reapply every 2–3 hours outdoors.
- Apply generously — two finger-lengths for face and neck.
- A strong pick for melasma and sensitive skin alike.
Alternatives
- Most conservative: mineral sunscreens (zinc oxide, titanium dioxide).
- Companion filters: Tinosorb S, Uvinul A Plus, Mexoryl (EU/Asia, not US).
- US users: mineral sunscreens (Tinosorb isn't FDA-approved).
The bottom line
Tinosorb M is a best-of-both-worlds hybrid filter — chemical absorption plus mineral-style reflection — that's broad-spectrum, photostable, low-cast, and extremely low-allergy. Pair it with Tinosorb S for top-tier protection; the only catch is it's unavailable in US sunscreens.
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