Overview

The body's principal intracellular antioxidant, and an entirely legitimate molecule with a largely illegitimate injectable market. Oral supplementation faces a real bioavailability problem; IV skin-lightening infusions face a real safety problem.

Not approved for human use anywhereNo approval anywhere for human use. Sold under research-use labelling. Lawful as an oral supplement. Injectable cosmetic use is unapproved and subject to import alerts.

At a glance

Regulatory status	A lawful oral supplement. Injectable glutathione for skin lightening is unapproved; FDA has warned against imported injectable products.
Drug class	Endogenous tripeptide antioxidant (glutamate-cysteine-glycine)
Route	Oral, intravenous, liposomal, inhaled
Half-life	Minutes intravenously
Evidence rating	2/5 Limited Evidence rating 2 out of 5: Limited Preclinical work plus scattered human reports, uncontrolled use, or negative trials.
Studied in	Oral bioavailability studies; small trials of oral glutathione for skin lightening; N-acetylcysteine (a precursor) has far better clinical evidence; no rigorous trials of IV glutathione infusion for cosmetic use.

How it works

Central redox buffer neutralising reactive oxygen species and supporting phase II hepatic detoxification via glutathione S-transferases. The skin-lightening claim rests on inhibition of tyrosinase and a shift from eumelanin toward pheomelanin production.

Evidence base

Rated 2 of 5 — Limited. Preclinical work plus scattered human reports, uncontrolled use, or negative trials.

Strong physiology, weak supplementation evidence, and a genuinely hazardous injectable market.

Benefits & potential uses

Bars indicate how well each claim is supported: three = strong human evidence, two = moderate, one = preliminary or preclinical.

Essential endogenous antioxidant Strong evidence

Its physiological importance is not in question — depletion is associated with oxidative stress in many disease states.
Supports hepatic detoxification Strong evidence

Central to phase II conjugation; the basis of N-acetylcysteine's use as the antidote in acetaminophen overdose.
Modest skin-lightening signal orally Preliminary

Small randomized trials of oral glutathione showed measurable reductions in melanin index over several weeks.
Better raised via precursors Moderate evidence

N-acetylcysteine and whey protein reliably raise intracellular glutathione and have far better evidence than direct supplementation.

Risks, cons & cautions

Bars indicate seriousness: three = serious or common, two = moderate, one = minor.

IV skin-lightening infusions are unapproved and unsafe Serious

FDA and several national regulators have warned against them following reports of severe adverse events including Stevens-Johnson syndrome, renal dysfunction and thyroid effects.
Poor oral bioavailability Moderate evidence

Standard oral glutathione is largely degraded in the gut; much of the supplement market ignores this.
Infection risk from unregulated infusion clinics Serious

Non-sterile compounding and IV administration in non-medical settings has caused serious infections.
Antioxidant supplementation is not uniformly beneficial Moderate evidence

High-dose antioxidants can blunt exercise adaptation and, in some trial contexts, have shown harm.
Skin-lightening motives and safety Moderate evidence

The cosmetic driver of this market pushes people toward high-risk unregulated products.

Who should avoid it

IV glutathione for cosmetic purposes
Asthma (inhaled forms have triggered bronchospasm)
Pregnancy for injectable use

If used under medical supervision, monitor

Renal and hepatic function if using injectable forms
Skin examination

Commonly confused with

These mix-ups cause real harm — two products sold under one name, or two molecules whose effects run in opposite directions.

GHK-Cu Cosmetic Ingredient Evidence 3/5

Both marketed for skin, both frequently offered by IV infusion clinics. Neither has evidence supporting intravenous cosmetic use, and IV glutathione has specific regulator warnings against it.

Compare side by side

Regulatory & legal status

Lawful as an oral supplement. Injectable cosmetic use is unapproved and subject to import alerts.

Infographic

Glutathione — benefits & risks at a glance Download SVG

Where to read further

We link to live literature searches rather than a frozen citation list, so you always see current results — including anything published after our last review.

antioxidantskin lighteningdetoxificationsupplement

Related peptides in Bone, Muscle & Other

Terms used on this page

Bioavailability: Bioavailability is the fraction of an administered dose that reaches the systemic circulation chemically unchanged, measured against an intravenous dose of the same drug.
Tyrosinase: Tyrosinase is the copper-dependent melanosomal enzyme that catalyses the rate-limiting first steps of melanin synthesis, making it the principal target of depigmenting agents.
Buffer and pH Adjustment: A buffer is a weak acid and its conjugate base that holds a formulation at a chosen pH, which determines a peptide's charge, its solubility, and which degradation reactions dominate.
Adverse Event (AE): An adverse event is any untoward medical occurrence in someone receiving a medicine, recorded whether or not the drug caused it, which is why an event table is not a harm table.
Intravenous Administration (IV): Intravenous administration delivers drug directly into the bloodstream, giving complete bioavailability by definition and making it the reference route against which all others are measured.
Import Alert: An import alert is an FDA instruction to field staff to detain specified imported goods without physical examination, shifting the burden onto the importer to prove the shipment complies.

This page is educational information, not medical advice. It cannot account for your medical history, medications, or risk factors. Do not start, stop or change any treatment based on it. Speak to a qualified healthcare professional who knows your case.