Which factor is NOT known to cause skin discoloration?

Excessive use of moisturizers typically does not lead to skin discoloration. The primary role of moisturizers is to hydrate the skin, helping to maintain the skin barrier and prevent dryness. While using certain products improperly may sometimes lead to irritation or breakouts, which can indirectly affect the complexion, actual discoloration—such as hyperpigmentation or mottling—is not a recognized consequence of overusing moisturizers.

On the other hand, hormonal changes can lead to fluctuations in melanin production, sometimes resulting in dark patches of skin. Sun exposure is well-documented as a significant cause of skin discoloration due to UV radiation stimulating melanin production as a protective response, which can contribute to sunspots and uneven skin tone. Various medications can also cause skin discoloration as a side effect, depending on their influence on melanin synthesis or skin sensitivity. Therefore, while the other factors are known contributors to discoloration, excessive moisturizer use is not associated with this issue.