BOTOX injections are measured in units, and the number of units you need depends on your aesthetic goals. For frown lines and forehead creases, 8 to 20 units are usually enough. For crow's feet, 10 to 15 units are typically needed. The areas being treated and the severity of your concerns determine how many units you'll need. BOTOX Cosmetic treatments are usually outpatient procedures that take less than 30 minutes, regardless of the number of units required to achieve the best results.