Is it possible that someone is allergic to glutathione injection? what are the odds?

Glutathione: Overall, taking glutathione or its precursors in reasonable amounts appears to be quite safe, although it should be avoided in people with milk protein allergies and in those who have received an organ transplant. There is also some concern, however, about the safety of taking glutathione for the one condition for which there is the greatest evidence of its usefulness: cancer.