Hydroquinone is a skin-lightening agent commonly used to treat conditions like hyperpigmentation, melasma, and age spots. It works by inhibiting the enzyme tyrosinase, which is essential for the production of melanin, the pigment responsible for skin color. Hydroquinone is available in various formulations, including creams and gels, and is typically applied directly to the affected areas. While effective for many, hydroquinone can cause side effects such as skin irritation or allergic reactions. Prolonged use may lead to a condition called ochronosis, which causes darkening of the skin. It is important to use hydroquinone under the guidance of a healthcare professional.