At what age can I start applying Botox?Botox ® Cosmetic is approved by the FDA for the treatment of moderate to severe frown lines in adult men and women, ages 65 and younger. It is not recommended for people under 18 years of age. Since Botox works best to prevent the onset of wrinkles, it is a good idea to start soon, before expression lines become permanent folds. If you start using Botox regularly at the age of 20, it is very probable that you will delay the onset of forehead wrinkles and crow’s feet significantly. When it comes to Botox, sooner is better!