- 4-OHA is a skin depigmenting agent with moderate efficacy and may be used for the treatment of hyperpigmentary disorders such as melasma and freckles.
- This agent decreases the number of melanin producing cells in the skin and can whiten the skin to a considerable degree.
- However, one should be aware of possible side effects such as skin irritation.
- Non-uniform depigmentation does not usually occur using 4-OHA. 4-OHA products are applied once to twice daily and the skin whitening effect usually becomes evident after 3-4 weeks of application. The maximum whitening effect is reached within 6-8 weeks. Thereafter, the product may be applied once to twice weekly to maintain the whitening effect. The combination of 4-OHA with tretinoin greatly enhances the whitening activity of 4-OHA.
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