Each individual responds uniquely to any medical aesthetic and health regime. It is recommended to do weekly sessions of Glutathione and Vitamin C for 3-5 months to see and notice optimal results. A maintenance program is recommended, and is safe for ongoing use and benefits, much like taking a potent dose of vitamins every 2-3 weeks but through an IV.
There are many factors, however, which will influence and hinder your outcome from Glutathione and vitamin C Benefits, such as:
Smoking
Sun exposure (not wearing a full spectrum sunblock)
Your genetics and ethnicity (the amount of melanin in the epidermis)
Other lifestyle factors; diet, etc.
The skincare being used (if you are doing IV therapy for solely skin benefits)