The scalp is actually a reasonably permeable surface compared to other skin areas, especially when you use a vehicle (the carrier liquid) designed for skin penetration
doi:10.1016/s0090-4295(98)00571-8 Morales A, Black A, Emerson L, Barkin J, Kuzmarov I, Day A
Although vitamin B12 is naturally found in animal products such as meat, dairy, and eggs, some people may be unhappy with a vitamin B12 deficiency due to diet, health, or age
BSH Guidelines for the diagnosis and treatment of cobalamin and folate disorders: Treatment of established cobalamin deciency should follow the schedules in the BNF (Grade 1A)
Step 1: Preparation and Sterilization First things first, wash your hands thoroughly