Generally, glutathione is said to be free of side effects. Considered safe by the Food and Drug Administration, no reports of harmful side effects have been published in any medical journals. There is one reported side effect has been contributed to glutathione, which is skin whitening. Skin whitening occurs when glutathione is taken in increased doses by modifying conversion of eumelanin (dark/brown/yellow pigmentation) to phaeomelanin (reddish white pigmentation). Many dermatologists use glutathione as a skin whitener and it has been proven to be very safe and effective.