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

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 anti-xoidant 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 , or found in the capsule form. Headaches , issues at the injection site, 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 I my opinion is 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 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 Hawaii 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 pill.

Glutathione is an anti-oxidant that is widely use for liver health and detoxification. As a result of beneficial effects, skin brightens and clarify as a result.  Widely use safely in Asia for years.  Make sure you get reliable product that is bioavailable.