Cosmetics · Quasi-drug actives
4-n-Butylresorcinol
4-n-ブチルレゾルシノール (4-n-Buchiru rezorushinōru)
Also known as: Butylresorcinol, POLA markets a preparation as Rucinol®
At a glance
| Category | Cosmetics |
|---|---|
| INCI name | Butylresorcinol |
| Japanese labeling name | 4-n-ブチルレゾルシノール |
| Common Japanese notations | 4-n-ブチルレゾルシノール |
| CAS number | 18979-61-8 |
| Origin | Synthetic (resorcinol derivative) |
| Typical functions | Quasi-drug whitening (medicated bihaku) active |
| Regulatory status in Japan | Approved as a quasi-drug (医薬部外品) whitening active by Japan's MHLW in 1998. Approval applied for by POLA Chemical Industries. |
4-n-Butylresorcinol is a synthetic resorcinol derivative approved as a quasi-drug whitening active in Japan in 1998. POLA Chemical Industries, the company that applied for and received the approval, markets its preparation of the ingredient under the registered trademark Rucinol®.
Classification
Tags below link to other ingredients sharing the same attribute, so you can pivot from one ingredient to its peers.
Product applications
Functions
Regulatory tags
Origin
Used in (typical product categories)
Finished-product categories that commonly include this ingredient in Japanese-market formulations.
- Medicated whitening lines (薬用美白) marketed under Kanebo brands
- Quasi-drug serums and lotions targeting dark spots
- Quasi-drug creams for hyperpigmentation
- Brightening face masks (medicated)
What it is
4-n-Butylresorcinol is the n-butyl-substituted resorcinol with the structure 4-n-butyl-1,3-benzenediol. It functions as a tyrosinase inhibitor in the melanin biosynthesis pathway, the basis for its quasi-drug whitening application.
Typical uses in Japanese products
Within Japan, the ingredient's commercial use is concentrated in POLA's medicated whitening lines marketed under Rucinol®.
Regulatory classification in Japan
Approved by MHLW as a quasi-drug whitening active in 1998 following POLA Chemical Industries' application. Permits the standard medicated whitening claim wording.
Regulatory classification in other markets
| EU | Butylresorcinol is listed in CosIng. Permitted for cosmetic use within applicable concentration ranges. |
|---|---|
| USA | INCI recognized. |
| China | Cosmetic use should be verified against current IECIC listings; resorcinol-family ingredients may have specific concentration considerations. |
| Korea | Permitted under KFDA / MFDS for cosmetic use. |
Example products
Example products are concentrated in POLA's branded medicated whitening lines. Specific SKU listings will be added after each product's current full ingredient list has been verified.
All brand names and product names referenced anywhere on this site are the property of their respective owners. Example entries are provided for informational purposes only and do not imply endorsement.
Related ingredients
References
- Japan PMDA — quasi-drug active ingredient approval registry
- POLA Chemical Industries corporate publications referencing Rucinol®
Last updated: 2026-04-22. Ingredient entries are reviewed at least annually against current regulatory listings.