Longevity
Your body's master antioxidant — a tiny three-part protein that shields your cells and helps clear out toxins.
Start here
Glutathione is a small molecule your body makes on its own from three amino acids, the building blocks of protein. Nearly every cell uses it to neutralize harmful, unstable molecules and to tag toxins so the body can flush them out 4, which is why it is often called the body's master antioxidant. It is sold as a dietary supplement and is not FDA-approved as a drug; the IV and inhaled forms are compounded or used off-label.
Think of glutathione as your cells' cleanup crew. Free radicals are like sparks that can start tiny fires of damage inside you. Glutathione throws water on those sparks. It also acts like a garbage tag — it sticks to poisons so your liver knows what to haul away. Once it has done its work, an enzyme recharges it so it can go again.
Your natural glutathione tends to drop with age, illness, and stress. Doctors have tested extra glutathione for conditions tied to oxidative stress — the wear-and-tear that builds up when free radicals outnumber your defenses. Taking it by mouth for 6 months raised the body's glutathione stores and boosted some immune cells 2, and getting it into the brain through the nose or a vein has been studied in Parkinson's disease 13. The biggest catch is delivery: swallowed glutathione is largely broken down before it reaches your blood.
Glutathione (GSH) works through several linked routes. As a direct antioxidant, the thiol (-SH) group (a sulfur-containing part) on its cysteine gives away electrons to neutralize reactive oxygen species (unstable molecules that damage cells). It also helps the enzyme glutathione peroxidase break down hydrogen peroxide and lipid peroxides (damaging molecules); in the process, GSH is oxidized (used up) into glutathione disulfide (GSSG). Then the enzyme glutathione reductase recharges it back into GSH using NADPH (a cell energy carrier), which keeps the GSH:GSSG ratio high. Through glutathione-S-transferase (an enzyme), GSH attaches to toxins and drug breakdown products (electrophiles), turning them into water-soluble thioethers that the body can excrete. It also adjusts how proteins work through reversible S-glutathionylation, attaching and removing GSH on cysteine units, which acts as a redox-signaling switch 4. Intact GSH is broken down by gamma-glutamyl transpeptidase (an enzyme) in the gut, so little gets into the body when swallowed (low oral bioavailability (how much actually gets absorbed and used)). Delivery through the nose (intranasal) has been shown to raise brain GSH as measured by magnetic resonance spectroscopy (a type of brain scan) 3, and delivery into a vein (intravenous) puts it directly in the bloodstream 1.
Evidence check
Some human studies
It has been tested in people, but only in small or early-stage studies. Promising, but not yet proven the way an approved medicine is.
Every numbered marker on this page links to one of the 12 sources at the bottom.
Antioxidant defense
The core role — directly neutralizing free radicals and powering antioxidant enzymes. Strongly supported by biochemistry.
Detoxification support
Tags and helps clear toxins and drug byproducts via glutathione-S-transferase.
Immune support
Higher oral dosing more than doubled natural killer cell activity in a 6-month trial.
The most-asked question
The research-reported range is 200 mg, once daily by mouth; iv and inhaled protocols are typically given 1–3 times per week. Studies used different doses for different situations — find yours:
First-time subcutaneous users, Assessing tolerance
100 mg per injection
Delivered under the skin, bypassing gut breakdown like the intramuscular (into a muscle) route shown effective in a controlled trial (600 mg IM every other day) 7. Subcutaneous-specific dosing is drawn from clinical practice rather than published trials, so start at the lower end to gauge tolerance. Most protocols use a 0.5–1 mL injection volume.
Routine subcutaneous antioxidant support
200 mg per injection (up to ~600 mg per week total)
The most common subcutaneous (under the skin) range used in practice. It mirrors the systemic (affecting the whole body) delivery of the controlled intramuscular (into a muscle) protocol 7; subcutaneous-specific numbers come from clinical use rather than trials. Rotate injection sites (abdomen, thigh) and use sterile, single-use supplies.
Everyday antioxidant support, Needle-free option
250 mg per day
The lower dose from the 6-month oral trial in 54 healthy adults; it raised glutathione stores roughly 17-29% in blood versus baseline, and levels returned to baseline within a month of stopping 2.
Stronger oral antioxidant and immune support
1,000 mg per day
The higher dose in the same 54-person trial raised blood glutathione about 30-35% versus baseline and more than doubled natural-killer immune-cell activity versus placebo by 3 months 2. In a separate 12-person pilot with no placebo arm, liposomal glutathione at 500-1,000 mg per day raised whole-blood glutathione up to 40% versus baseline within 2 weeks 12.
Supervised clinical protocols, Bypassing gut breakdown
1,400 mg per infusion
Clinic-administered. In the 4-week Parkinson's trial (21 people: 11 on IV glutathione 1,400 mg three times weekly, 10 on placebo), reported adverse events were similar in the two groups, no one withdrew because of them, and the treatment did not show a statistically significant benefit over placebo on symptom scores 1. Must be given by a healthcare professional.
Targeted brain-delivery research interest
100-200 mg per dose
Trial dosing in Parkinson's: 100 or 200 mg three times daily for 3 months in 45 people — symptoms improved in every group including placebo, neither dose beat placebo, and one of the 15 people in the 200 mg arm developed cardiomyopathy 10. An earlier 30-person trial of 300-600 mg per day divided found adverse events no more frequent than placebo 9. A single 200 mg dose raised brain glutathione in 15 people (about a 269% rise in the glutathione-to-creatine signal at 45 minutes versus baseline) 3. Uses a compounded nasal spray; trial samples lost potency to 72-81% of label within 4-6 weeks 3.
Peer-reviewed injectable protocol, Bypassing gut breakdown
600 mg per injection
This is the dose used in a placebo-controlled, double-blind trial, where 600 mg intramuscular (into a muscle) every other day for 2 months improved sperm motility and structure 7. Given by a healthcare professional or trained self-injector.
Skin tone and pigmentation, Needle-free skin support
2% oxidized glutathione (GSSG) lotion
Applied to the skin, not injected. In a placebo-controlled trial, a 2% oxidized-glutathione lotion twice daily for 10 weeks lightened skin tone and improved the skin barrier 8. Topical use acts locally on the skin and does not meaningfully raise whole-body glutathione.
The ceiling: Oral trials used up to 1,000 mg/day for 6 months 2; IV studies used 1,400 mg three times weekly 1. Higher amounts should only be used under medical supervision.
Reconstitution, in plain words
Peptides usually arrive as a freeze-dried powder in a small vial. “Reconstitution” just means adding sterile water back in so you can measure a dose. Here's how it works for Glutathione:
Oral forms come ready to use — no reconstitution needed. For a clinic IV vial supplied as a powder, a pharmacist or clinician reconstitutes it per the product label; this is not a home procedure.
For oral use, simply take the labeled number of capsules to reach your target (for example, two 500 mg capsules for a 1,000 mg dose). Injectable dosing is calculated and administered by a healthcare professional.
Three quick questions — your vial, your water, your dose — and it tells you the exact syringe mark. “Find dose amount” is preloaded with Glutathione's recorded schedule.
Injection sites & technique
Subcutaneous (under the skin) injection is the most common self-administered route in practice. Clinical studies also used intravenous (IV) infusion 1 and intranasal spray 3; intramuscular (into a muscle) injection is used in some clinics.
Timing
Oral glutathione is commonly taken in the morning. Some people split it or take it on an empty stomach, though trials simply used daily dosing 2.
Can be taken with or without food. An empty stomach may slightly reduce competition from dietary proteins, but consistency matters more than timing.
Often paired with vitamin C, N-acetylcysteine (NAC, a cysteine source the body uses to build glutathione), alpha-lipoic acid, or selenium, which support the glutathione recycling system.
The honest list
These show up most often. They usually fade as your body adjusts.
Across oral and IV studies, most people had no significant side effects 12.
What to do No action needed for most users; start low and build up.
Sulfur-containing glutathione can have a rotten-egg odor, most noticeable with inhaled or liquid forms.
What to do Use capsules or rinse the mouth; this is harmless.
Worth knowing about, but most people never see these.
Some people notice digestive discomfort with oral doses, especially higher amounts.
What to do Take with food, lower the dose, or split it through the day.
Reported mainly with nebulized/inhaled use.
What to do Stop inhaled use if it persists and speak with your clinician.
Rare, but if any of these happen, stop and contact a medical professional.
In people with mild asthma, nebulized glutathione caused cough, breathlessness and measurable airway narrowing, likely from sulfite sensitivity 5.
What to do Avoid the inhaled form if you have asthma. Seek urgent care for breathing trouble.
Week by week
Is it right for you?
This information is educational and not medical advice. Glutathione is not an FDA-approved drug. Talk with a qualified healthcare provider before starting, especially if you have asthma, are pregnant or breastfeeding, or take other medicines.
Studied to reduce some chemo side effects, but could affect treatment — use only under oncologist guidance
Discuss with your doctor before combining
No specific peptide interactions are well documented; generally considered compatible
Helps recycle glutathione back to its active form
Supplies cysteine the body uses to build glutathione
Supports glutathione regeneration
A cofactor for glutathione peroxidase
Raising your body's own glutathione helps mop up free radicals — the unstable molecules behind cell wear-and-tear. Six months of daily oral dosing measurably increased body stores 2.
Glutathione tags toxins and drug byproducts so your liver can clear them out through the glutathione-S-transferase pathway 4.
In the 6-month oral trial, the higher dose more than doubled the activity of natural killer cells, a front-line immune defender 2.
Glutathione has a reassuring safety record in trials, but the trials are small. In the 6-month oral trial (54 healthy adults taking 250 or 1,000 mg a day), blood glutathione rose and returned to baseline after a 1-month washout 2. In the IV Parkinson's trial (21 people: 11 on 1,400 mg three times a week, 10 on placebo), reported adverse events were similar in the two groups and no one withdrew because of them 1. Intranasal glutathione was tolerated over 3 months in a 30-person trial (placebo, 300 or 600 mg per day) with no substantial difference in adverse events between groups 9; in the follow-up 45-person trial, one of the 15 people on the highest dose (200 mg three times daily) developed cardiomyopathy — a weakening of the heart muscle 10. The clearest warning is for the inhaled form: in 8 people with mild asthma, nebulized glutathione (600 mg) dropped lung function (FEV1) 19% versus 1% after placebo, with coughing in 4 of 8 and breathlessness in 3 of 8 — the researchers attributed the airway narrowing to sulfite formation 5.
Most human studies are small pilot trials lasting weeks to months, so long-term safety at high doses is not fully mapped. The strongest safety data are for oral and short-course IV use 12. Inhaled use carries a specific asthma caution: 600 mg nebulized dropped FEV1 19% (versus 1% on placebo) in 8 people with mild asthma 5, while a separate 12-person asthma study found the same 600 mg inhaled dose protected against 'fog'-challenge airway narrowing (a 6% FEV1 fall versus 20% after placebo) 11. The two findings stand together; the first study traces the risk to sulfite formation 5.
Keeping it good
Keep oral capsules and powders in a cool, dry place away from light and humidity. Liposomal liquids often need refrigeration — follow the label. Glutathione's sulfur group is sensitive to air and moisture.
Once a clinic vial is mixed or a liquid is opened, refrigerate and use within the timeframe on the label. Do not freeze unless directed.
Not our opinion — the published record
2009
In 21 people with Parkinson's, IV glutathione (into a vein) 1,400 mg three times a week for 4 weeks was well tolerated with no safety concerns. Scores for movement and daily living improved by a mean of 2.8 units more than placebo, but the difference was not statistically significant (P=0.32), meaning it could be chance.
Hauser RA, Lyons KE, McClain T, Carter S, Perlmutter D
2015
In 54 non-smoking adults, glutathione by mouth (250 or 1,000 mg/day for 6 months) raised the body's glutathione stores in a dose-dependent way (a higher dose raised them more): about 30–35% in blood compartments and 260% in cheek cells at the high dose. Natural killer cell activity (a type of immune cell that attacks infected cells) more than doubled at the high dose by 3 months.
Richie JP Jr, Nichenametla S, Neidig W, et al.
2016
In 15 people with mid-stage Parkinson's, a single 200 mg dose through the nose raised measured brain glutathione (by MRS, a type of brain scan). The glutathione-to-creatine ratio rose by roughly 269% at 45 minutes and stayed up for at least an hour (P<0.001).
Mischley LK, Conley KE, Shankland EG, et al.
2023
Reviews how glutathione protects cells. It neutralizes peroxides (damaging molecules) as a partner to glutathione peroxidase (an enzyme), cycling between GSH and GSSG (its active and used-up forms) with the help of glutathione reductase and NADPH. It tags toxins for removal through glutathione-S-transferase (an enzyme), and fine-tunes how proteins work through reversible S-glutathionylation (attaching and removing glutathione on proteins).
Kennedy L, Sandhu JK, Harper ME, Cuperlovic-Culf M
1997
In people with mild asthma, inhaled (nebulized) glutathione caused cough, breathlessness and measurable airway narrowing. The effect tracked with sulfite sensitivity, a warning that the inhaled route needs caution in asthma.
Marrades RM, Roca J, Barberà JA, et al.
1988
Traces glutathione's history: first seen in yeast by de Rey-Pailhade in 1888 (he called it philothion), extracted and named by F. Gowland Hopkins in 1921, and confirmed in 1929 as a tripeptide (a chain of three amino acids) of glutamate, cysteine and glycine.
Simoni RD, Hill RL, Vaughan M (historical review of Hopkins' work)
1993
In a placebo-controlled, double-blind crossover trial (neither patients nor doctors knew who got the drug, and each person tried both), glutathione given as 600 mg by intramuscular injection (into a muscle) every other day for 2 months significantly improved sperm motility and structure in men with infertility. This is peer-reviewed evidence that injected glutathione has measurable effects.
Lenzi A, Culasso F, Gandini L, Lombardo F, Dondero F
2014
In a double-blind, placebo-controlled split-face trial (each person's two face halves got different treatments) in 30 healthy women, a 2% oxidized glutathione (GSSG) lotion applied twice daily for 10 weeks significantly reduced the skin melanin index (a measure of skin darkness), giving a lighter skin tone, and improved the skin's moisture barrier, with no significant adverse effects.
Watanabe F, Hashizume E, Chan GP, Kamimura A
2015
In 30 people with Parkinson's randomized to placebo, 300 mg/day, or 600 mg/day of glutathione through the nose (divided into three daily doses) for 3 months, there were no substantial differences between groups in the number of adverse events, and all groups met the tolerability criteria.
Mischley LK, Leverenz JB, Lau RC, et al.
If this isn't the right fit
Your questions
Both things are true. Plain glutathione is largely broken down by a gut enzyme, so little reaches your blood intact. But a careful 6-month study still found that daily oral doses of 250–1,000 mg raised the body's glutathione stores and boosted some immune cells 2. Liposomal forms and precursors like NAC are designed to improve absorption.
Glutathione works quietly. Body stores build over weeks, with immune changes seen by about 3 months and fuller blood levels by 6 months in studies 2. Many people will not feel a dramatic day-to-day change.
NAC (N-acetylcysteine) is a building block your body uses to make its own glutathione. Glutathione is the finished molecule. Because NAC absorbs well by mouth, some people use it as an easier way to raise glutathione indirectly.
12 sources
Every numbered marker on this page points to one of these. Same sources, same numbering as the Glutathione research profile on Peptide Initiative.
Want the deep science?
Every claim on this page traces back to the research database behind Peptide Initiative — studies, citations, clinical trial data, and the technical detail we deliberately left out here.
Open the research profileThis guide is education, not medical advice. Talk to a clinician before taking anything.
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