Glutathione Dosage: What the Research Used, by Route

Glutathione dosage depends on the route because swallowed glutathione is partly broken down in the gut and liver. A single 3 g oral dose did not raise blood glutathione in seven healthy volunteers (Witschi et al., 1992), yet daily oral dosing over months did (Richie et al., 2015). Oral, intravenous and injected doses therefore cannot be converted into one another.

These are doses used in published studies. They are not a recommendation, and the prescription routes are dosed and administered by a clinician.

No published human trial has defined an injectable glutathione dosage for subcutaneous or intramuscular use. The doses clinicians use for injection come from clinical practice, not from a dose-finding study, so we do not publish a range as if it were one.

Injectable glutathione avoids gut breakdown. A subcutaneous or intramuscular injection is absorbed from under the skin or from muscle; only an IV enters the bloodstream directly. No human trial has shown that injection raises glutathione inside cells more than oral glutathione, which did raise blood and cell levels over six months (Richie et al., 2015). Our glutathione injections are prescribed on that honest footing, and glutathione side effects covers what to watch for.

What a prescriber weighs when setting a dose

When setting a dose, a prescriber weighs why glutathione is being used, your body size and age, how well you tolerate it, and how you respond over time.

• Why it is being used at all — general antioxidant support is a different goal from adjunct use alongside another therapy.
• Body size, age, and baseline oxidative stress markers where they have been measured.
• Tolerance, which is usually good, but injection-site reactions do occur.
• Response over time. A starting dose is a starting point, not a setting.

In the Protocol MD glutathione protocol, a physician reviews your history first, prescribes glutathione only if it is appropriate, and sets and adjusts the dose. You do not choose it from a menu.

1,400 mg three times weekly for four weeks is the best-documented IV glutathione dose. It comes from a randomized, placebo-controlled pilot in 21 people with Parkinson's disease. Glutathione was well tolerated, and motor scores did not differ significantly from placebo (Hauser et al., 2009). Glutathione is not an approved treatment for Parkinson's; the trial is cited as the source of a dose, not as evidence of benefit.

IV glutathione also carries a current safety issue. In August 2026 the FDA reported at least 30 patients with adverse events after IV glutathione that compounding pharmacies had made from one lot of dietary-supplement-grade glutathione. Reported events included fever, chills, sepsis-like symptoms and hospitalizations (FDA, 2026). Ingredient grade and sterility matter as much as the number of milligrams.

The routes are compared in more detail in glutathione IV vs injection. The best-documented IV dose is a figure from one small trial, not a recommended dose.

250 mg and 1,000 mg daily are the oral glutathione doses with the best trial data. In a six-month randomized, placebo-controlled trial in 54 healthy non-smoking adults, blood glutathione rose at 1, 3 and 6 months at both doses. At six months the 1,000 mg group showed increases of 30–35% in red cells, plasma and lymphocytes, and levels returned to baseline after a one-month washout (Richie et al., 2015).

Why a single oral dose shows little and a daily one does not

A single oral dose of glutathione shows little because much of it is broken down in the gut and liver into cysteine, glycine and glutamate, while daily dosing over months does raise levels. A single 3 g dose did not raise blood glutathione in seven healthy volunteers over the following four and a half hours (Witschi et al., 1992). Daily use over months is a different picture, as the six-month trial showed. Oral absorption is limited and slow, not zero.

Liposomal glutathione dosage

500 mg and 1,000 mg daily were the doses in a one-month pilot of liposomal glutathione in 12 healthy adults. Blood glutathione rose within a week, with the largest increases at two weeks (Sinha et al., 2018). The study was a small pilot funded by a liposomal glutathione supplier. "Liposomal" is not a regulated term.

Worth saying plainly, even though we sell the injectable: for someone with no specific clinical reason to use a prescription route, oral or liposomal glutathione is inexpensive, available without a prescription, and reasonable.

N-acetylcysteine (NAC) is the indirect route to glutathione, because it is not glutathione itself. It supplies cysteine, the amino acid that limits how fast the body builds glutathione. In a small study of eight older adults, two weeks of cysteine and glycine supplementation raised red-cell glutathione to the level seen in younger adults (Sekhar et al., 2011). For some people a precursor is a more practical way to support glutathione than swallowing the molecule.

We do not give an NAC dose here. NAC can interact with some medications, so it is worth reviewing with a clinician rather than choosing a dose from a label.

Stated plainly, glutathione's regulatory status is that it is not an FDA-approved drug. Injectable glutathione is prepared by 503A compounding pharmacies, which means it has not been through FDA review for safety, effectiveness or manufacturing quality. That is true of our product as much as anyone else's, and it is the honest frame for every number above.

The FDA has also warned consumers that it has not approved any injectable drug for skin lightening, and US marshals have seized injectable glutathione whitening kits (FDA consumer update, 2015). The evidence for that use is weak. In regulatory terms, every injectable glutathione, including the compounded glutathione Protocol MD prescribes, is an unapproved product.