Is Glutathione Pill A Good Lightening Agent? What Are Potential Side Effects?

While oral glutathione pill can be helpful for skin lightening, there is significant risk to one's kidney function at higher dose. I would stay away for now until the drug is better studied and approved by the U.S. FDA.

Glutathione has overall has a very high safety profile, naturally occurring in ones body , in fact low levels measured have been associated with some diseases. Its a powerful antioxidant and free radical scavenger. However studies are limited and a search of literature shows only few and rare complications with use of Intravenous (through a needle into your veins) administration. These include stomach aches , allergic reactions most likely from something in the manufacturing as opposed to the Glutathione itself . A recent review in the Indian Journal of Dermatology is a great review and summary of all the studies that have been published. There they mention very rare complications including speculation about kidney failure and necrosis of the skin. Again these are rare and few reports of any negative effects, so in my opinion its safe.
We have used IV Glutathione in 100's of patients in our practice and have seen various patient satisfaction rates with patient observed skin lightening. Most patients think they benefit. Yet like anything cosmetic plastic surgery it is fairly subjective and there are not good studies to give a peer reviewed answer. We add Vitamin C  and N acetyl cysteine to our treatment which is known to not lighten the skin itself,  but enhance the effect of medications which lighten skin. 
Until more studies are done there simply is not a definitive scientific answer. Our practice is in Mumbai,India and its very popular with Asians so we provide this treatment in light of the overall safety profile in a medically observable environment. That is to say we know the quality of the products we use as opposed to what one may buy online as a capsule or pillor IV formulation.

Glutathione is a well known antioxidant in the body .This is also  widely used in asian countries for skin lightening. Glutathione oral products are not well absorbed from the intestine and had to be metabolized to to another molecule before this is taken up by the body cells. Glutathione can be absorbed intact into the blood stream when administered in IV form as a nutritional supplement . Certain oral glutathione precursors like N Acetylcysteine, R-Alpha Lipoic Acid, Selenium and Silymarin can be taken to increase the body's supply of glutathione.  Glutathione  inhibits tyrosinase enzyme which then switches the production of eumelanin to phaeomelanin.  Its lightening effects appear to work better when combined with IV vitamin C. IV glutathione when combined with IV vitamin C helps  to stay  in its most active form.  Glutathione also appears to work  by eliminating the body of free radicals or toxins that lead to hyperpigmentation, age spots, sun spots, wrinkles and conditions such as melasma. Vitamin C has been scientifically proven to raise the levels of glutathione in the body. The potential side effects of the IV injection include anaphylaxis, nausea, phlebitis and abnormal liver test. Certain oral preparations may help increase the Glutathione body storage hence be effective not only as antioxidants but skin lightening.
Ladie Arana-Domondon, MD, FACP