The effectiveness and time it takes for stretch mark oil to work can vary depending on various factors, including the severity of the stretch marks, individual skin type, and the specific product being used. While some people may notice improvements in the appearance of their stretch marks within a few weeks of regular use, others may require several months of consistent application to see noticeable results. Stretch mark oils generally work by moisturizing and nourishing the skin, improving its elasticity and promoting collagen production. They may also contain ingredients that help reduce inflammation and fade the appearance of stretch marks over time. However, it's important to note that stretch marks are a form of scarring, and while certain products may help diminish their appearance, they cannot completely eliminate them.