Ingredient guide
4-Methoxysalicylic Acid (4-MSA)
INCI name · 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.
What it is
Shiseido-developed tyrosinase inhibitor; salicylic acid backbone with methoxy group enhances melanocyte specificity.
Evidence receipt
No linked study yet
No verified study is linked to this exact ingredient and route. The guidance below describes conventional use; it is not evidence of efficacy.
When to use it
Evenings. Exfoliating acids sit best away from daylight hours.
A couple of nights a week to start.
Where it sits
An evening treatment step. After cleansing, before the heavier layers go on.
- Cleanse
- 4-Methoxysalicylic Acid
- Hydrate
- Moisturise
Also found as
Related
Compare products
Browse product comparisonsWhere to find it
Examples, not a ranking. A product lookup can confirm identity and background; a verdict still needs the full ingredient list.
Product discovery is not efficacy proof. These examples are not ranked by commission.
Common questions
What does 4‑Methoxysalicylic Acid do for skin?
It focuses on reducing the appearance of uneven pigmentation by slowing melanin formation in the skin’s upper layers.
Is 4‑MSA suitable for sensitive or combination skin?
It is generally considered gentle and is often paired with soothing ingredients, making it a fit for sensitive and combination skin types.
How is 4‑MSA used in skincare?
You’ll usually find it in brightening serums or emulsions designed for overall tone improvement.
Stay in the loop
Get launch updates and occasional product news.
Unsubscribe anytime.
Checking a complete formula? Paste or photograph the ingredient list for the full verdict.
Personal guidance, not medical advice.