I am taking glutathione capsule 500 mg together with a 500 mg. Vitamin C as an ntioxidant but after 2 days i am having headaches can this possibly be the cause of my headache?

Yes. Stop taking so much unless it is doctor recommended. You could be suffering from an overdose of one or both things. Talk to your doctor if your headaches don't stop a few days after you stop taking the supplements (allow it time to clear your system). Depending on what you are using these products for, you should stop taking them for a bit, then start again on a lower dose.