Turning the hair grey is one of the gluthathione's side effects?

There are no significant side effects with glutathione. It is not recommend to be given at the same time as any other IV products. For example, vitamin C can oxidize it and render it ineffective if given along with it. It is contraindicated to give glutathione while a person is taking cancer chemotherapy drugs since glutathione increases the ability of the liver to process chemicals. This may cause the chemotherapy to be less effective.

Ask your doctor. While it should not cause the greying, there may be other factors going on.