Under-eye treatments can be safely started in the early 20s if dark circles begin to appear and do not improve with lifestyle changes or skincare. At a younger age, dermatologists usually recommend gentle and preventive treatments such as medical creams, mild peels, or PRP therapy to improve skin quality and pigmentation. As age increases, concerns like volume loss, skin thinning, or deeper pigmentation may develop, which might require advanced treatments like laser procedures or under-eye fillers.