When a wellness influencer promotes a tiny orange strip that dissolves on the tongue as a fast track to reduced inflammation, better immunity, more energy, and glowing skin, the implied promise is that taking the supplement can do no harm. But researchers are increasingly cautioning that over-the-counter glutathione supplements may carry risks not yet fully understood.
Isaac Harris, an associate professor at the University of Rochester Medical Center’s Wilmot Cancer Institute, said his work is exploring whether high doses of the peptide could, in some cases, fuel the growth of cancer cells. “The worst thing is that, actually, it could be harming you,” Harris said. Glutathione has become a staple among biohacking enthusiasts, who call it the “mother of all antioxidants.” They hawk it in capsule, liquid, gel, and powder forms, as well as in skincare serums, patches, and injectables.
The gelatinous strips are marketed on the premise that they allow glutathione to bypass destructive enzymes in the digestive system and enter the bloodstream directly. Under the care of a physician, glutathione therapy can be beneficial in specific clinical cases, such as treating acetaminophen overdoses or managing HIV symptoms.
But experts say there is not much evidence to support the many sweeping claims made for over-the-counter glutathione supplements sold for general wellness or cosmetic purposes.
The Biology of Glutathione
Glutathione is a compound made up of three amino acids: glutamate, cysteine, and glycine. It is produced by the liver and found in nearly every human cell, where it protects the body from oxidative stress caused by free radicals, said Zhaoping Li, chief of the division of clinical nutrition and a professor of medicine at UCLA Health. The molecule exists in two forms: the active reduced form, known as GSH, and the oxidized form, called GSSG.
Most of the body’s glutathione pool is typically found in the reduced state. The compound was first isolated in 1921 by British biochemists Frederick Gowland Hopkins and William Harden, and it has been studied for nearly a century as a biological antioxidant.
Early research examined its role in yeast fermentation before scientists recognized its presence across nearly all living cells, including plants, fungi, animals, and some bacteria. By the 1970s, biochemists had mapped its structure as a tripeptide linked by an unusual gamma peptide bond. That bond shields glutathione from rapid breakdown, giving it molecular stability that allows it to circulate in cells at unusually high concentrations, especially in the liver. The liver’s central role in glutathione production was later confirmed by genetic studies showing that mice lacking hepatic synthesis could not survive without intervention.
Because of the gamma peptide linkage, glutathione resists digestion in the stomach and small intestine, unlike most peptides, which are broken down into individual amino acids before absorption.
Clinical Applications and Unanswered Questions
The clinical applications of glutathione emerged gradually. By the 1980s, researchers found that the compound plays a key role in helping the liver process drugs and toxins, leading to its use in emergency medicine, most notably in treating acetaminophen poisoning.
Over time, studies also linked glutathione to immune function and cellular repair, especially in conditions involving chronic oxidative damage. Today, while some evidence supports its therapeutic use under medical supervision, far less is known about the safety and efficacy of high-dose over-the-counter supplements, particularly those marketed for general wellness or cosmetic benefits. Wellness enthusiasts often assume the worst that could happen if they take glutathione is that it is simply not effective.
But Harris and other researchers are investigating whether excessive supplementation might influence cellular pathways in ways not yet fully understood. Concerns persist about potential unintended effects, including the possibility that high doses could, in some cases, fuel the growth of cancer cells.
Li noted that glutathione, as a natural antioxidant, protects the body from oxidative stress, but the consequences of flooding the system with additional glutathione remain an open question. The source material advises: Consult your doctor for medical advice. For now, the gap between the assured claims of social media videos and the cautious findings of scientific research is wide. Glutathione is vital for health, but whether buying it in a strip, a capsule, or a patch delivers the advertised benefits — or might pose hidden risks — is not something the available evidence can answer with confidence.
