Peptifact

Glutathione Dosage: FDA's Reviewers Recommended Against It, Its Own Advisory Committee Voted 8-5 the Other Way, and Intravenous Half-Life Is 10 to 15 Minutes

The dose question for injected glutathione is settled by its pharmacokinetics before it reaches the evidence. FDA's review put the intravenous half-life at 10 to 15 minutes with plasma back to baseline in half an hour — and its advisory committee then voted to keep it compoundable anyway.

Robert F · Edited by Caroline S · Published 2026-09-18

Illustration: A clear glass vial and a pipette on a cool grey slate surface, lit by soft natural light.
Illustration

Most pages in this catalogue have to establish whether a dose figure exists. This one has a different shape: the figures exist commercially in abundance, and the compound's own pharmacokinetics make them difficult to interpret before the evidence question is reached at all.

The best source on it is not a label — there isn't one — but a public FDA review and the transcript of the meeting where it was argued.

The kinetics, first

FDA's pharmacokinetic review, presented to its Pharmacy Compounding Advisory Committee on 8 June 2022:

"Intravenous glutathione given in healthy volunteers showed a half-life between 10 and 15 minutes, and plasma levels returned to pre-dose values 30 minutes after dosing."

That single finding reorganises the dose question. Whatever an infusion is meant to achieve has to happen inside roughly half an hour, or through some downstream consequence of that half hour which the review did not find established. And it means the commercially quoted figure — a number of grams in a bag — is not the variable that matters. For a compound with those kinetics, rate and repetition are, and no registered protocol in this use has established either.

On the oral route the review was equally direct: "Hydrolysis in the intestine is considered a primary obstacle for oral glutathione absorption," with the authors of the absorption study it cited conceding that how much direct absorption explained their own results "is not known."

The vote FDA lost

Going into the meeting, the agency's position was stated plainly on the record: "FDA is proposing that glutathione not be included on the 503 Bulks List."

The committee voted the other way. The tally read into the record was 8 yeses, 5 noes, 1 abstention in favour of placing it on the list.

That is an unusual result and worth naming rather than smoothing over. The agency's own reviewers assessed the safety and effectiveness evidence and recommended against inclusion; the advisory committee it convened recommended inclusion, largely on the strength of long clinical use described by members during the discussion — one noted nearly two decades of clinically using compounded glutathione.

The disagreement was not unanimous on either side. Dr Anita Gupta's recorded reason for voting no was that although glutathione "is known to be stable, endogenous, and it's well characterized, there is unclear evidence, reproductive evidence, and developmental evidence."

A committee vote is advisory. It does not by itself place a substance on the list.

What the review found on the commercial use

Injected glutathione's largest market is skin lightening, and FDA's review addressed it at length.

Its conclusion: a small intravenous study "appears to suggest it lightens the skin, but the effects seem to dissipate after discontinuation," while other studies "failed to show a skin-lightening effect with glutathione or were inadequately designed." For the oral route, "there are insufficient data to support the effectiveness of oral glutathione for skin lightening." A review article summarised in the presentation put it as: "The evidence of IV glutathione as a therapeutic modality for improving skin tone or pigmentation is minimum and contradictory."

Then a distinction that is easy to read past and is the sharpest thing in the review. Even where lightening was observed, the review found no data indicating that the effect "provides clinical benefit to address a disease or condition such as managing disorders of hyperpigmentation."

Changing an appearance and treating a condition are different claims. They carry different evidence requirements, and the market for this compound generally elides them.

The adverse-event record

FDA's review broke its FAERS findings down by route. For intravenous glutathione:

  • Two anaphylaxis reports, onset between 30 minutes and 24 hours. Both patients discontinued. One was rechallenged and experienced anaphylaxis again.
  • Hepatotoxicity, with liver enzymes measured at 22 to 26 times normal.
  • Infusion reactions and hypersensitivities.

Hypersensitivity was also reported on the inhaled and oral routes.

FAERS is a spontaneous reporting system: these are reports, not rates, and no denominator can be constructed from them. The rechallenge is nonetheless the most informative single item in the list, because a reaction that recurs on deliberate re-exposure is the one least easily explained by something else in the patient's history.

Supply, and a filing in the wrong category

FDA's published Drug Master File list holds nine glutathione records, three of them active:

DMF Type Holder Filed
37051 II Shandong Jincheng Bio-Pharmaceutical Dec 2024
7799 II Kyowa Hakko Bio (L-glutathione oxidized) Dec 1988
41240 IV Anmol Chemicals (GLUTATHIONE USP) Jan 2025

Type IV is FDA's category for "Excipient, Colorant, Flavor, Essence, or Material Used in Their Preparation" — not the drug-substance category. One of the three live filings for this compound is registered as an excipient. The general caution about what a DMF does and does not prove is on the sources page: they are not required by statute and are neither approved nor disapproved.

What is unambiguous

Glutathione is a tripeptide — glutamate, cysteine, glycine — and so is one of the few compounds in this catalogue that needs no qualification about whether it is a peptide at all. It is also genuinely central to human cell biology, as the principal intracellular antioxidant and a workhorse of liver detoxification chemistry. Peptide Lexicon's glutathione entry covers the structure, including the unusual bond joining its glutamate residue.

Neither of those facts is an argument about injecting it, and the distance between them is where this compound's marketing lives.

The summary

There is no approved injectable glutathione product and no approved injectable for skin lightening of any kind. The best available source on its dosing is a regulatory review rather than a label, and that review found a 10-to-15-minute intravenous half-life, plasma back to baseline in half an hour, contested oral absorption, an efficacy record its authors called minimum and contradictory, and a small set of serious spontaneous adverse-event reports including one recurrent anaphylaxis on rechallenge. FDA recommended against compounding it; its advisory committee voted 8-5 to allow it.

Every figure here is reported from that public record with its date. None is offered as a figure to use, and decisions about administering anything to a person belong with a clinician.

Frequently asked questions

What dose of glutathione does the evidence support?

No figure in this record functions as a dose in the way a label figure does, and the pharmacokinetics are the reason rather than the evidence base. FDA's review of intravenous glutathione in healthy volunteers found a half-life of 10 to 15 minutes, with plasma levels back to pre-dose values 30 minutes after dosing. A compound cleared that fast presents a dosing question that is mostly about frequency and infusion design, and no registered protocol in this indication has answered it. The figures circulating commercially — typically expressed as grams per intravenous drip — do not trace to a dose-finding study, and FDA's reviewers did not identify one.

What did FDA's advisory committee actually decide?

It disagreed with FDA. Going into the vote, FDA's stated proposal was that glutathione not be placed on the 503A bulk drug substances list, which would have meant compounders could not use it under that section once the rule was final. The Pharmacy Compounding Advisory Committee voted 8 yes, 5 no, 1 abstention in favour of placing it on the list. That split is unusual enough to be worth naming: the agency's own scientific review recommended against inclusion and the advisory committee it convened recommended for it, largely on the strength of decades of clinical use described by members during the discussion. A committee vote is advisory and does not itself change the list.

Why does the 10-to-15-minute half-life matter?

Because it sits underneath every claim about what an infusion accomplishes. FDA's review found that after intravenous administration in healthy volunteers, plasma glutathione returned to pre-dose values within 30 minutes. Whatever effect is being sought has to occur inside that window or through some downstream consequence of it, and the review identified no study establishing the latter. It also reframes the dose question: for a compound with those kinetics, the meaningful variables are infusion rate and repetition rather than the total grams in a bag, and none of the commercial figures is expressed that way.

Is injected glutathione effective for skin lightening?

FDA's review concluded the evidence does not support it. Its summary was that one small intravenous study appeared to suggest skin lightening, with the effect dissipating after discontinuation, while other studies failed to show an effect or were inadequately designed, and that there are insufficient data for oral glutathione. A review article it cited concluded that the evidence for intravenous glutathione as a therapy for skin tone or pigmentation 'is minimum and contradictory'. The review made one further distinction that is easy to miss: even where a lightening effect was observed, no data indicated that it provides clinical benefit for a disease or condition such as a disorder of hyperpigmentation. Changing an appearance and treating a condition are different claims with different evidence requirements.

What adverse events has FDA recorded for the intravenous route?

FDA's review broke its FAERS findings down by route and reported these for intravenous glutathione: two anaphylaxis reports, with onset ranging from 30 minutes to 24 hours, in which both patients discontinued and one who was rechallenged experienced anaphylaxis a second time; hepatotoxicity with liver enzymes at 22 to 26 times normal; and infusion reactions and hypersensitivities. Hypersensitivity was also reported on the inhaled and oral routes. FAERS is a spontaneous reporting system, so these are reports rather than incidence rates, and no denominator can be derived from them. The rechallenge detail is the most informative single item, because a reaction that recurs on re-exposure is the pattern least easily attributed to something else.

Is glutathione a peptide?

Yes — and unusually for this catalogue, with no qualification needed. It is a tripeptide of glutamate, cysteine and glycine. What makes it atypical is not its classification but its role: it is not a signalling molecule like most entries here but a working cellular chemical, the principal intracellular antioxidant and a central component of liver detoxification. Peptide Lexicon's entry on the compound covers the structural detail, including the unusual bond joining its glutamate residue. Both facts are true simultaneously and neither is an argument about injecting it.

Is there an approved injectable glutathione product?

No. FDA has approved no injectable product for skin lightening of any kind, and there is no approved glutathione injection. The substance's regulatory position is the compounding question the 2022 advisory committee was convened to address, which is a different question from approval — it concerns whether a pharmacy may compound with the bulk substance at all. FDA's published Drug Master File list carries three active glutathione records, and one of those three is filed under Type IV, the excipient and colorant category, rather than the drug-substance category.

Why is oral glutathione discussed separately from injected?

Because absorption is contested and FDA's review said so. Its stated position was that hydrolysis in the intestine is considered a primary obstacle to oral glutathione absorption, and that the authors of the absorption study it reviewed concluded the extent to which direct absorption explained their findings is not known. A buccal lozenge study over eight weeks found decreased melanin indices, with the authors themselves calling for a larger placebo-controlled randomised trial. So the oral record is a separate and weaker evidence base rather than a more convenient version of the injected one, and FDA found insufficient data to support oral glutathione for skin lightening specifically.