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Ingredient guide
4-methoxysalicylic acid
In short
4‑Methoxysalicylic Acid (4‑MSA/4‑MSK) is a brightening ingredient developed to target pigment formation more selectively. It’s often used to help skin look more even-toned.
Reviewed against published evidence · editorially independent · no brand pays for placement
Works for
Tone
Skin type
Sensitive · Combination
Best used
Evening
What it is
Shiseido-developed tyrosinase inhibitor; salicylic acid backbone with methoxy group enhances melanocyte specificity.
Also found as
Related
Where to find it
Shiseido White Lucent MicroSpot Serum
Shiseido White Lucent Brightening Gel Cream
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Common questions
It focuses on reducing the appearance of uneven pigmentation by slowing melanin formation in the skin’s upper layers.
It is generally considered gentle and is often paired with soothing ingredients, making it a fit for sensitive and combination skin types.
You’ll usually find it in brightening serums or emulsions designed for overall tone improvement.
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Personal guidance only · For clinical concerns, see a dermatologist.