Glutathione is a three-amino-acid peptide that the body makes for itself in every cell. It is sold two ways: as an injection, usually an intravenous drip from a clinic or a compounded vial, and as a capsule or powder sold as a supplement. The question of which "works better" is asked constantly, and the honest answer is that no study has asked it. What can be done is to lay the two records side by side and show how different they are.
The injected amounts in circulation and FDA's 2022 review are on our glutathione dosage page; the contamination and adverse-event record for injections is on our glutathione injection side-effects page. This page compares the routes.
Side by side
| Injected (IV or subcutaneous) | Oral (capsule, powder) | |
|---|---|---|
| What reaches the blood | All of it, at once | Very little intact glutathione in short studies |
| How long it stays in blood | Half-life 10–15 minutes; baseline by 30 minutes (FDA review, 2022) | Single dose: no measurable rise over 270 minutes (1992) |
| Effect on body stores, longest trial | Not measured in a long-term controlled trial found here | +30–35% after 6 months at 1,000 mg/day; gone after 1-month washout (2015) |
| Regulatory status (US) | Compounded; no approved product | Sold as a dietary supplement |
| Regulatory status elsewhere | Licensed injectable in Italy (TAD 600 mg/4 mL) | — |
| Largest documented harm | Product contamination (endotoxin, recalls) | None specific found in the trials read |
| Head-to-head trial | None | None |
The injected record: fast in, fast out
FDA's pharmacokinetic review, presented to its compounding advisory committee on 8 June 2022, is blunt: intravenous glutathione 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 means injection solves the absorption problem and creates a persistence problem. A drip delivers every milligram, and the blood is clear of the excess within half an hour. Whatever an infusion is meant to change has to happen inside cells during that window, and the studies FDA reviewed did not establish what that is.
Outside the United States there is a licensed injectable. In Italy, Biomedica Foscama markets TAD 600 mg/4 mL — a vial of glutathione sodium salt with a solvent ampoule. Its current phase 3 trial (NCT06296212, started June 2024, 178 patients planned) gives 600 mg in 50 mL of saline twice a day for five days to people with pneumonia, against a saline placebo, looking at heart-muscle injury. It is a hospital drug being tested in hospital patients, which is a different thing from a wellness drip.
The oral record: broken down, but not always without effect
The oral evidence divides cleanly by how long people took it.
Single dose, 1992 (PMID 1362956). Seven healthy volunteers took 0.15 mmol/kg — about 3 g. Over 270 minutes, plasma glutathione, cysteine and glutamate did not rise significantly. The authors concluded that because glutathione is broken down by gamma-glutamyltransferase in the gut and liver, "it is not possible to increase circulating glutathione to a clinically beneficial extent by the oral administration of a single dose of 3 g."
Four weeks, 2011 (PMID 21875351). Forty healthy adults took 500 mg twice a day or placebo. Glutathione status in red blood cells — reduced, oxidised and their ratio — was unchanged, and so were two oxidative-stress markers.
Six months, 2015 (PMID 24791752). Fifty-four non-smoking adults took 250 mg or 1,000 mg a day, or placebo. Blood glutathione rose at both doses by the first month and kept rising. At six months the high dose had raised levels 30–35% in red cells, plasma and lymphocytes, and 260% in cells scraped from the inside of the cheek. One month after stopping, levels were back to baseline.
These are not contradictory so much as measuring different things. The first two looked for intact glutathione arriving in the blood, and found none. The third looked at what the body had stored after months of daily intake, and found more — but it did not establish whether intact glutathione was absorbed or whether the gut's breakdown products (cysteine above all, the building block in shortest supply) were used to make more. FDA's 2022 review said the same: hydrolysis in the intestine "is considered a primary obstacle," and the extent of direct absorption "is not known."
Two further placebo-controlled trials put the oral route to a clinical test. In 60 Thai medical students, 500 mg a day for four weeks reduced the melanin index at two of six skin sites (PMID 20524875). In the GROW trial, 58 children with cystic fibrosis took oral glutathione or placebo for 24 weeks; there was no difference in growth or in inflammatory markers, and it was well tolerated (PMID 32960827).
The formulations in between
Liposomal capsules, sublingual sprays and dissolving tablets are attempts to get past the gut. The one controlled-release orobuccal tablet study found here (PMID 26649136) reported blood glutathione rising within 30 to 60 minutes in 15 healthy volunteers. It had no placebo arm. None of these formats has been compared with injection.
Where the harms differ
On the oral side, the trials read here report no adverse effects that separated glutathione from placebo; the skin-lightening authors still wrote that long-term safety "has not been established."
On the injected side, the dominant documented harm is not the molecule but the product: compounded and imported injectable glutathione has a record of contamination, endotoxin findings and recalls, which is set out with dates on our glutathione injection side-effects page. An intravenous line adds its own risks — infection and vein irritation — that do not exist for a capsule. How an unlabelled powder becomes an injectable solution, and what can go wrong, is covered on our reconstitution page.
What is not established
- Whether either route changes glutathione inside the tissues people take it for — liver, skin, brain — rather than in blood cells.
- Whether the oral rise in the 2015 trial came from absorbed glutathione or from its breakdown products.
- Whether repeated infusions raise stored glutathione at all; no long-term controlled trial of injection was found.
- Any comparison of the two in the same people. The question this page is named after has no trial.
Glutathione's chemistry is in Peptide Lexicon's glutathione entry, and its skin uses are covered by PeptideGlowJournal's glutathione for skin page. Questions about using either route, especially by injection, belong with a clinician.
Sources and dates
- FDA Pharmacy Compounding Advisory Committee, 8 June 2022 — glutathione pharmacokinetic review, as quoted on our dosage page and re-read 2026-10-05.
- Witschi A, et al. The systemic availability of oral glutathione. Eur J Clin Pharmacol. 1992;43(6):667–9. PMID 1362956.
- Allen J, Bradley RD. Effects of oral glutathione supplementation on systemic oxidative stress biomarkers in human volunteers. J Altern Complement Med. 2011;17(9):827–33. PMID 21875351.
- Richie JP Jr, et al. Randomized controlled trial of oral glutathione supplementation on body stores of glutathione. Eur J Nutr. 2015;54(2):251–63. PMID 24791752.
- Arjinpathana N, Asawanonda P. Glutathione as an oral whitening agent: a randomized, double-blind, placebo-controlled study. J Dermatolog Treat. 2012;23(2):97–102. PMID 20524875.
- Bozic M, et al. Oral glutathione and growth in cystic fibrosis: a multicenter, randomized, placebo-controlled, double-blind trial (GROW). J Pediatr Gastroenterol Nutr. 2020;71(6):771–7. PMID 32960827.
- Buonocore D, et al. Bioavailability study of an innovative orobuccal formulation of glutathione. Oxid Med Cell Longev. 2016;2016:3286365. PMID 26649136.
- ClinicalTrials.gov NCT06296212 (Biomedica Foscama, TAD 600 mg/4 mL), read via API v2, 2026-10-05.
- PubMed E-utilities, glutathione oral vs intravenous/injection comparison query, 2026-10-05 (3 records, none a head-to-head trial).
Corrections go to the contact page.