Also called glabella lines for which Botox injections have received FDA approval. It develops with time between the eyebrows as two vertical lines (A.K.A. the 11) as a result of repeated squinting and scowling. When Botox is injected into the scowling (corrugator) muscles, it causes these muscles to relax and gives one a more relaxed and enhanced appearance. Depending on the size and strength of these muscles our physicians will determine how many units are needed. The average amount of Botox used for the Frown lines is around 20-24 Botox units for a female and about 20 to 30 units for male patients as their facial muscles are often larger, thicker and stronger. Another benefit of Botox injected between the eyebrows is often improved tension headaches and even migraines related to the repeated tightening of these muscles.