4-n-Butylresorcinol
Tyrosinase and TRP-1 inhibitor, known as Rucinol. Works on both melanin synthesis steps, so it delivers stronger depigmentation.
Evidence by route
Topical application
In vitro data show a strong effect compared with hydroquinone. Patient studies remain scarce, with part of the data coming from Korean and Japanese groups.
How to read tiers A–F
- CWeak evidence. In vitro data, open-label studies, or expert consensus
Tolerability and safety
- Irritation potential
- Low
- Allergen risk
- Moderate
- Pregnancy
- Caution
- Suitable for
- Normal, Oily, Combination, Dry
About this ingredient
4-n-Butylresorcinol (trade name Rucinol) is a synthetic resorcinol derivative. Among the most potent topical inhibitors of melanogenesis available in EU OTC cosmetics. Mechanism. Inhibits tyrosinase and the related TRP-1 protein – two key melanin synthesis enzymes. The dual action blocks melanogenesis more fully than arbutin or kojic acid. In vitro, 4-n-butylresorcinol is roughly 100-fold more potent than hydroquinone at tyrosinase inhibition (Khemis 2007). Where applied. Depigmenting serums and creams at 0.1–0.3%. In Spain: Sesderma Azelac Ru, Mesoestetic Cosmelan Hidra Ac Pro, Martiderm DSP-Bright. Often combined with retinol, niacinamide, azelaic acid, and vitamin C for additive effect. Evidence base. Khemis 2011 (n=28, 12 weeks, 0.3%) showed a 32% mMASI reduction in melasma – comparable to hydroquinone 4% but with lower irritation rate. Huh 2010 (n=23, 8 weeks, 0.1%) confirmed reduction of post-UV pigmentation. Safety. SCCS rated 4-n-butylresorcinol as acceptable at up to 0.3% in leave-on products (2018 opinion). Irritation and contact dermatitis occur in 3–8% of patients at initiation. Does not photosensitise. Pregnancy and lactation – use with caution. No direct pregnancy data; topical systemic absorption is low but non-zero, so avoid without necessity. Alternative for gestational melasma: azelaic acid 15–20% (pregnancy-approved) plus SPF 50+. Particularly suitable for. Persistent melasma, post-inflammatory hyperpigmentation after acne, lentigo. Not for sensitive skin or active rosacea.
Frequently asked questions
Is 4-n-Butylresorcinol safe during pregnancy?
4-n-Butylresorcinol should be used with caution during pregnancy. Consulting a dermatologist or OB-GYN is advisable.
What skin types is 4-n-Butylresorcinol for?
4-n-Butylresorcinol suits: normal, oily, combination, dry.
What is 4-n-Butylresorcinol and what does it do in cosmetics?
Tyrosinase and TRP-1 inhibitor, known as Rucinol.
What's the INCI name for 4-n-Butylresorcinol?
The INCI name is 4-n-Butylresorcinol. It may also appear as: Rucinol.
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