If you are taking Glutathione for skin lightening, then my recommendation will be concentrating on skin hydration instead of skin lightening. But consult a specialist first. If they give you green light then you can take Glutathione, Vitamin C, Vitamin B12, B Complex, and minerals.
How many Glutathione should you take? It depends on your physical and skin condition. Take advice from a specialist then decide how many tablets you should take.
Also, take some time to know about Glutathione. There are lots of online health-related blog and article site where you find about Glutathione. Hope, this video will help you out...
Don't forget to know about the side effects and consult your doctor, make sure you are always on the safe side.