What is NAC?
NAC is short for "N-acetylcysteine." It's a slightly modified form of the amino acid cysteine (one of the small building blocks of protein) that your body can use more easily.
Cysteine is a building block of glutathione. Glutathione is the most powerful antioxidant your body makes on its own (antioxidants clear out free radicals that "rust" your cells), and it handles detox, especially in the liver. Of all the ingredients needed to make glutathione, cysteine is the one your body is most likely to run short on.
For reference, in some countries NAC is sold as a medication for loosening mucus (an expectorant). In the US, it's sold as a supplement. At one point it was hard to find in the US too, because of questions about its drug status.
NAC benefits: where it may help
- Antioxidant and liver protection: By raising glutathione levels, it may help protect liver cells and flush toxins out of the body. It's also the ingredient hospitals give by IV as an antidote to patients who've taken too much Tylenol (acetaminophen).
- Mucus and runny nose: It breaks the bonds in thick mucus to thin it out. That's why it's popular with people who have weak airways and lots of mucus.
- Alcohol: It grabs and clears the toxic byproduct made when alcohol is broken down (acetaldehyde). But in studies, its effect on hangovers themselves was weaker than expected.
- Insulin resistance (when blood sugar doesn't come down well even with insulin present): There's a fair amount of research showing improvement in people with polycystic ovary syndrome (PCOS).
- Heavy metal removal: Its sulfur is used to grab heavy metals and carry them out. But for this purpose, be sure to read the caution below.
NAC vs glutathione: which should you take?
| NAC | Glutathione | |
|---|---|---|
| How it works | Gives your body the raw material to make glutathione itself | You take finished glutathione |
| Raising glutathione in the body | Considered better at it than oral glutathione | Easily broken down in the gut |
| Cost | Inexpensive | Expensive |
How to take NAC: dose and timing
Bottom line: start with 600 mg a day.
| Goal | Daily dose |
|---|---|
| General health and antioxidant support | 600 mg |
| Focused support for liver, mucus, etc. | 600 mg twice a day (1,200 mg) |
| Before drinking | 1,000–1,200 mg |
- It's fine to take on an empty stomach. Some say an empty stomach is better for absorption.
- If you feel nauseated or get heartburn, switch to after meals.
- For long-term goals like heavy metal removal, plan on at least 6 months.
Higher doses (over 1,200 mg a day) are used by doctors to manage medical conditions. Don't just raise the dose on your own.
Who should be careful
- People with stomach ulcers or a sensitive stomach: It can irritate the stomach lining and cause pain.
- Pregnant women: Always talk to your doctor before taking it.
- Light sleepers: There are quite a few reports of trouble sleeping after taking it. If that happens, take it in the morning.
- People using it for heavy metal detox: Some papers suggest it may move heavy metals toward the brain, so be cautious. Talk to a professional.
NAC side effects and storage
At normal doses, serious problems other than stomach upset are rare.
- Nausea, heartburn, vomiting: The most common. NAC's distinctive sulfur smell makes these more likely. Switch to after meals or lower the dose.
- Allergies: Hypersensitivity reactions like hives and itching are reported relatively often.
- Stacking antioxidants: Taking several antioxidant supplements at high doses all at once can actually throw things off balance. There's even a case of hair loss in someone taking high doses.
- Very large amounts: Taking several times the recommended dose can strain the liver and kidneys.
Medications and conditions to watch
- Note Tylenol (acetaminophen) — Used in hospitals as the antidote for overdose — few problems with typical combined use
- Check Being treated for stomach ulcers or gastritis — May irritate the stomach lining and cause pain — talk to your doctor
Combinations
Works well with: Glycine, Vitamin C, Multivitamin, Milk thistle
How it appears on the label
| On the label | What it is | What it means |
|---|---|---|
| N-Acetyl Cysteine N-Acetyl-L-Cysteine NAC | NAC (N-acetyl cysteine) | An amino acid your body uses to make glutathione |
| Sustained Release Sustain | Sustained release | A form that dissolves slowly |
Best NAC (N-Acetylcysteine) supplements on Amazon, compared
Bottom line
We checked the labels of 21 popular NAC (N-Acetylcysteine) products on Amazon: 13 recommended, 8 depend on your needs, 0 not recommended.
- Best overall — Life Extension N-Acetyl-L-Cysteine 600 mg (60 Vegetarian Capsules): NAC 600 mg per capsule, single ingredient (Per serving: 600 mg)
- Best value — Best Naturals NAC 600 mg (120 Capsules): NAC 600 mg per capsule, single ingredient (Per serving: 600 mg)
- High dose — NOW NAC 1,000 mg (120 Tablets): Single-ingredient tablet with just NAC 1,000 mg (Per serving: 1000 mg)
- Slow release — Jarrow Formulas N-A-C Sustain 600 mg (60 Tablets): NAC 600 mg per tablet, made to dissolve slowly (Per serving: 600 mg)
- Simple ingredients — Pure Encapsulations NAC 600 mg (90 Capsules): NAC 600 mg per capsule; the only other ingredients are a plant capsule and fat-soluble vitamin C (antioxidant) (Per serving: 600 mg)
Recommended 13
NAC 600 mg with Selenium & Molybdenum (100 Veg Capsules)
N-acetylcysteine + a little selenium · Per serving: 600 mg · Cost per day: low
- NAC 600 mg per capsule, with just a small 25 mcg of selenium
- Label says 1 capsule twice a day (1,200 mg a day) — for basic support, 1 capsule is enough
- 2 capsules a day give selenium 50 mcg — usually plenty of room even with a multivitamin
First-timers, people who'll start at 600 mg and go to 2 capsules if needed
View on Amazon Find on iHerbNAC 1,000 mg (120 Tablets)
N-acetylcysteine only (tablet) · Per serving: 1000 mg · Cost per day: low
- Single-ingredient tablet with just NAC 1,000 mg
- 1 tablet a day is within the focused-support range (600–1,200 mg) — don't increase to the label max of 3 on your own
- Label says to consult a doctor if you take medication like nitroglycerin
- Among the lower cost per day in this comparison
People who want just 1 tablet a day for focused support (liver, mucus)
View on Amazon Find on iHerbN-Acetyl L-Cysteine (NAC) 600 mg (180 Capsules)
N-acetylcysteine only · Per serving: 600 mg · Cost per day: low
- NAC 600 mg per capsule, single ingredient; label says 1 a day
- Exactly the basic daily dose of 600 mg
- 180 capsules, among the lowest cost per day in this comparison
Basic 600 mg daily support, people for whom price matters
View on Amazon Find on iHerbN-Acetyl-L-Cysteine 600 mg (60 Vegetarian Capsules)
N-acetylcysteine only · Per serving: 600 mg · Cost per day: low
- NAC 600 mg per capsule, single ingredient
- Label says 1 capsule 1–3 times a day — easy to adjust from 600 mg to 1,200 mg
- Low cost per day at 1 capsule
First-timers, people adjusting between 1 and 2 capsules depending on their goal
View on Amazon Find on iHerbN-A-C Sustain 600 mg (60 Tablets)
N-acetylcysteine time-release tablet (dissolves slowly) · Per serving: 600 mg · Cost per day: high
- NAC 600 mg per tablet, made to dissolve slowly
- Label says 1 tablet 1–2 times a day, on an empty stomach with fruit juice
- Higher cost per day than other 600 mg single-ingredient products
People who want a slow-dissolving tablet once or twice a day
View on Amazon Find on iHerbNAC 600 mg (90 Capsules)
N-acetylcysteine only · Per serving: 600 mg · Cost per day: high
- NAC 600 mg per capsule; the only other ingredients are a plant capsule and fat-soluble vitamin C (antioxidant)
- Label says 1 capsule 1–3 times a day, between meals
- Higher cost per day than other 600 mg single-ingredient products
People who want few additives, people worried about allergies
View on Amazon Find on iHerbNAC N-Acetyl Cysteine 600 mg (100 Capsules, 3 Pack)
N-acetylcysteine only · Per serving: 600 mg · Cost per day: low
- NAC 600 mg per capsule, single ingredient; label says 1 a day
- The title says vegan, but the label lists a gelatin capsule — vegetarians, check
- 3-bottle, 300-capsule bundle, so low cost per day
People taking 600 mg a day long-term (vegetarians, check the capsule)
View on Amazon Find on iHerbNAC 500 mg (90 Capsules)
N-acetylcysteine only · Per serving: 500 mg · Cost per day: high
- NAC 500 mg per capsule, single ingredient, few fillers
- Label says 1 capsule 2–3 times a day (1,000–1,500 mg) — for basic support, 1–2 a day is enough
- Higher cost per day in this comparison at 2 capsules
People who want smaller amounts per capsule to split through the day
View on Amazon Find on iHerbNAC 600 mg (120 Capsules)
N-acetylcysteine only · Per serving: 600 mg · Cost per day: low
- NAC 600 mg per capsule, single ingredient
- Label says 1 capsule 1–2 times a day, on an empty stomach with fruit juice
- Gelatin capsule — not for vegetarians
- Lowest cost per day in this comparison at 1 capsule
People for whom price matters most, basic 600 mg daily support
View on Amazon Find on iHerbNAC Detox Regulators (60 Veggie Capsules)
N-acetylcysteine + selenium and molybdenum · Per serving: 600 mg · Cost per day: high
- NAC 600 mg per capsule with 50 mcg each of selenium and molybdenum
- Label says 1 capsule twice a day with meals (1,200 mg a day)
- 2 capsules a day give selenium 100 mcg — check that it stays at 400 mcg or less with your multivitamin's selenium
- Vanilla-flavored capsule
Focused support at 2 capsules a day, people not taking other selenium
View on Amazon Find on iHerbNAC 900 mg (120 Capsules)
N-acetylcysteine only · Per serving: 900 mg · Cost per day: high
- NAC 900 mg per capsule; the only other ingredients are a plant capsule and fat-soluble vitamin C
- Label says 1 capsule 1–2 times a day between meals — 1 capsule lands between 600 and 1,200 mg
- Higher cost per day at 1 capsule
People who want a bit more than 600 mg in one capsule
View on Amazon Find on iHerbNAC 600 mg (60 Capsules)
N-acetylcysteine only · Per serving: 600 mg · Cost per day: average
- NAC 600 mg per capsule, single ingredient
- Label says 1 capsule 1–2 times a day — easy to adjust between 600 mg and 1,200 mg
- Gelatin capsule — not for vegetarians
People adjusting between 1 and 2 capsules a day
View on Amazon Find on iHerbNAC N-Acetyl-L-Cysteine 500 mg (90 Capsules)
N-acetylcysteine only · Per serving: 500 mg · Cost per day: average
- NAC 500 mg per capsule, single ingredient
- Label says 1 capsule 2–3 times a day (1,000–1,500 mg) — for basic support, 1–2 a day is enough
- Average cost per day at 2 capsules
People who want smaller amounts per capsule to split through the day
View on Amazon Find on iHerbDepends on your needs 8
NAC N-Acetyl Cysteine 1200mg (250 Capsules)
N-acetylcysteine only (per seller) · Per serving: 1200 mg · Cost per day: low
- Per seller: NAC 1,200 mg in 2 capsules, 600 mg each
- 1,200 mg in the title is for 2 capsules — 1 is enough for basic support
- Peppermint flavor, gelatin capsule
- Not verified in the label database
People for whom price matters (check the label yourself)
View on Amazon Find on iHerbNAC 1,200mg with Quercetin (240 Capsules)
N-acetylcysteine + quercetin (per seller) · Per serving: 1200 mg · Cost per day: average
- Per seller: NAC 1,200 mg + quercetin 100 mg in 3 capsules
- 400 mg per capsule makes it awkward to hit 600 mg
- 100 mg quercetin is more of a bonus
- Not verified in the label database
People who'll split 1,200 mg a day into 3 capsules (check the label yourself)
View on Amazon Find on iHerbNAC 1200 mg with Selenium, B6 & B12 (120 Capsules)
N-acetylcysteine + selenium, vitamin B6 and B12 (per seller) · Per serving: 1200 mg · Cost per day: average
- Per seller: NAC 1,200 mg in 2 capsules
- No amounts on the product page for the selenium, B6 and B12 — hard to check overlap with a multivitamin
- Label says take 2 capsules at once
- Not verified in the label database
Focused support at 1,200 mg a day, people not taking a multivitamin (check the label yourself)
View on Amazon Find on iHerbNAC N-Acetyl Cysteine Capsules (120 Capsules)
N-acetylcysteine only (per seller) · Per serving: 1000 mg · Cost per day: high
- Per seller: NAC 1,000 mg in 2 capsules, 500 mg each
- Label says up to 2 capsules a day, on an empty stomach
- The product page notes that the sulfur smell is normal
- Not verified in the label database
People who want to split into 500 mg capsules (check the label yourself)
View on Amazon Find on iHerbNAC 1300mg (240 Capsules)
N-acetylcysteine only (per seller) · Per serving: 1300 mg · Cost per day: average
- Per seller: NAC 1,300 mg in 2 capsules (it also says 600 mg per capsule, so the listing is inconsistent)
- 2 capsules per the label is a bit more than the usual max (1,200 mg) — start with 1
- Label says on an empty stomach
- Not verified in the label database
People taking about 600 mg with 1 capsule a day (check the label yourself)
View on Amazon Find on iHerbNAC 1,000mg Per Serving with Reduced Glutathione (240 Capsules)
N-acetylcysteine + reduced glutathione (per seller) · Per serving: 1000 mg · Cost per day: average
- Per seller: NAC 1,000 mg + glutathione 50 mg in 3 capsules
- About 333 mg per capsule, so you need 3 a day
- Oral glutathione is easily broken down in the gut, so 50 mg is more of a bonus
- Not verified in the label database
People fine with 3 capsules a day (check the label yourself)
View on Amazon Find on iHerbNAC 600 mg (200 Capsules)
N-acetylcysteine only (per seller) · Per serving: 600 mg · Cost per day: low
- Per seller: NAC 600 mg per capsule, single ingredient, 1 a day with a meal
- Plant-based capsule
- 200 capsules, low cost per day
- Not verified in the label database
Basic 600 mg daily support (check the label yourself)
View on Amazon Find on iHerbN-Acetyl-L-Cysteine 1600 mg (100 Capsules)
N-acetylcysteine only · Per serving: 1600 mg · Cost per day: average
- NAC 800 mg per capsule, single ingredient; the only filler is cellulose
- Label says 2 capsules a day (1,600 mg) — more than the usual 600–1,200 mg, so start with 1
- Taking just 1 capsule halves the cost per day
People taking 1 capsule (800 mg) at a time; for higher amounts, talk to a professional
View on Amazon Find on iHerbWant it in one pill with others? Compare liver support combos →
Frequently asked questions
Can I take NAC on an empty stomach?
Yes, it's fine on an empty stomach. But if you feel nauseated or get heartburn, switch to after meals.
Which is better, NAC or glutathione?
Many say NAC is better at raising glutathione in the body than oral glutathione. It's also inexpensive, so it's a good place to start.
Does NAC help with hangovers?
It may help reduce the toxic byproduct made when alcohol is broken down (acetaldehyde). But in studies, its effect on hangover symptoms themselves was weaker than expected.
I can't sleep after taking NAC
That's been reported fairly often. If you took it in the evening, try switching to the morning.
How much NAC should I take a day?
The usual amount is 600 mg a day, and if needed, up to 600 mg twice a day. Talk to a professional before going higher.
My NAC smells like rotten eggs
NAC naturally has a smell because of its sulfur. But it's sensitive to moisture and heat and spoils easily, so keep the lid tightly closed and store it somewhere cool.
Related concerns
Last updated 2026-10-12