Hythiol (L-Cysteine)
Sulfur-containing amino acid accelerating melanin metabolism and normalizing skin turnover
About This Treatment
Hythiol tablets contain L-cysteine 80mg, insurance-covered in Japan. L-cysteine as a sulfur-containing amino acid provides whitening through three mechanisms: tyrosinase inhibition, shifting eumelanin to pheomelanin production, and promoting melanin excretion via accelerated turnover. Also serves as a glutathione precursor with antioxidant effects.
Mechanism of Action
L-cysteine: ①binds tyrosinase active site to inhibit melanin synthesis, ②reacts with dopaquinone to form cysteinyl-DOPA, promoting pheomelanin over eumelanin, ③accelerates epidermal turnover for melanin excretion, ④enhances glutathione synthesis for antioxidant defense against melanocyte activation.
Indications
Expected Results
Melanin index reduction observed from week 4. 12-week RCT confirmed significant melanin index improvement vs placebo. Enhanced with vitamin C combination. Skin brightness improvement typically noticed at 2-3 months.
Clinical Evidence
Risks & Side Effects
Generally safe. Rare GI symptoms. Theoretical cystine stone risk with prolonged high doses. May affect insulin secretion (caution in diabetes). Reports of increased gray hair (possible side effect of melanin suppression).
Interested in this treatment?
Start with an AI skin analysis to check your current skin condition