The way we come to a conclusion about how fast a supplement works is through studies. In clinical trials, researchers are able to keep track of changes in the body and skin to evaluate what’s happening and when.
Skin care supplement clinicals usually span several months: Within this time frame, we’re usually able to see if something is effective—and to what extent.* See, your epidermis renews itself every 46 to 50 days through a process called desquamation, so within three months, you should be able to see how the new skin cells being generated respond to the new routine. Many people say this process happens every 30 days, but that’s been proved to be a misconception.
For skin benefits, 12 weeks (i.e., three months) is a common duration in which you can see full results according to robustly designed research. For example, this 12-week study found that the patients taking a collagen supplement experienced enhanced skin elasticity, hydration, and density.* Another found that respondents experienced smoother skin texture.* This additional study measured skin-related outcomes (such as hydration, elasticity, and wrinkles) at both six and 12 weeks, with significant results at the latter duration.*
Some studies suggest you may be able to see results sooner. This research investigation reported statistically significant skin elasticity enhancement at four weeks.* Another suggests that results were even greater at eight weeks.* Finally, this clinical trial measured skin markers at two, four, six, and eight weeks—with noticeable results at six and eight weeks but not before.*
Essentially, the scientific evidence to date indicates you may see improvements within the second month of use, but for full results, you should stick with it until at least three months.