Why Tretinoin Is Best Used at Night: The Science, Myths, and Modern Best Practices
The debate over whether to apply retinoids in the morning or evening is settled by the fundamental chemistry of the molecule. Tretinoin (all-trans retinoic acid) is the gold standard for treating acne and photoaging, but its effectiveness depends entirely on its stability during application. In 2026, clinical guidelines remain firm: tretinoin is strictly a nighttime…