Deep nourishing moisturizers are designed to hydrate and improve the skin's texture and barrier function. Generally, they do not cause the skin to become darker.

However, a few points to consider:

• Ingredients: Some moisturizers may contain ingredients like fragrances, preservatives, or certain oils that could cause irritation or allergic reactions in sensitive individuals, potentially leading to temporary darkening or hyperpigmentation.

• Sun Exposure: If a moisturizer does not contain sunscreen, using it alone without sun protection can leave your skin vulnerable to UV rays, which can cause darkening or tanning.

• Underlying Skin Conditions: Sometimes, skin darkening is related to other factors like inflammation, hormonal changes, or skin conditions rather than the moisturizer itself.

If you notice your skin darkening after using a particular moisturizer, it might be due to an allergic reaction or sensitivity. Discontinue use and consult a dermatologist for personalized advice. Always choose products suitable for your skin type and consider using a broad-spectrum sunscreen daily to protect your skin from UV damage.