Glutathione common uses, half-life, side effects and more

Glutathione is a tripeptide of glutamate, cysteine, and glycine that every cell makes and uses as its main internal antioxidant. People take it as an ordinary oral supplement and receive it as a skin-lightening drip in clinics. Skin lightening is the most common reason people seek it out. Oral capsules are sold legally as a supplement. The injectable form is approved nowhere for skin lightening and the evidence behind that use is weak.

• Skin lightening and a more even complexion
• General antioxidant support
• Liver and detoxification goals
• Immune function
• Anti-aging and wellness drips

Daily for capsules and once or twice weekly for injection

Oral capsules run 250 to 1,000 mg a day. The most studied amount is 500 mg a day split into two doses. Clinic injections run 600 to 1,200 mg into a vein once or twice a week. That injection range comes from manufacturers rather than from a trial or a guideline. The one injection study ran a fixed six-week course. No cycling schedule has been established so any weeks-on and weeks-off plan is invented.

The half-life in blood after an injection is roughly 10 to 15 minutes so levels fall fast. Cell stores stay raised much longer than the blood level suggests. Oral and liposomal capsules raise body stores gradually rather than spiking the blood. Those stores return to baseline within about a month of stopping.

• Liver dysfunction reported in about a third of participants in one small injection study
• Injection-site pain, redness, or bruising
• Rash and other skin reactions
• Severe allergic reaction including anaphylaxis reported in a single injection case
• Oral capsules were well tolerated in trials with mild digestive complaints occasionally reported

Glutathione is the cell's main internal antioxidant. It works mostly as the partner molecule for an enzyme that neutralizes hydrogen peroxide and damaged fats. It also reacts with some free radicals directly though that route matters less. A second enzyme family uses it to tag toxins so the body can excrete them. The body recycles the spent form back into the active form. It also helps restore vitamins C and E. The skin-lightening explanation is that it blocks the copper enzyme that builds pigment and shifts pigment production toward a lighter type. That explanation is plausible but not well established.

The evidence is weak for the use people most want it for. Skin lightening rests on a few small short trials of oral and topical glutathione that found modest effects. The longest oral trial ran 12 weeks in 60 women. Injected glutathione has no completed blinded randomized trial for skin lightening at all. The one published injection study was open-label, found minimal benefit, and reported side effects in every treated patient. Several placebo-controlled trials do show that oral dosing raises the body's glutathione stores. Those stores fall back to baseline after stopping. Trials in Parkinson's disease found no benefit over placebo.

• Injected glutathione is not an approved treatment for skin lightening and no blinded trial shows that it works
• The Philippine drug regulator has warned that injecting it for skin lightening has caused severe skin reactions, thyroid problems, and kidney problems
• Serious infection and air embolism have followed unsterile or incorrect injection technique so the source and the technique matter as much as the compound
• Inhaled glutathione narrowed the airways in people with mild asthma though the researchers attributed that to a breakdown product in the solution rather than to glutathione itself
• Avoid it in pregnancy and breastfeeding since no safety data exist either way
• An infusion of more than 100 mL in 12 hours breaks anti-doping rules on infusions even though glutathione itself is not a banned substance