N-Acetyl Cysteine

N-Acetyl Cysteine (NAC) is a powerful antioxidant that works to protect the body against an array of oxidative stress issues including mood disorders, inflammation, infections, sleep, and much more (1, 2). 

In the body, NAC is transformed into cysteine. Cysteine is an amino acid that is important for regenerating another vital antioxidant, glutathioneWith around 1000 clinical trials, NAC is scientifically proven to prevent damage and inflammation, as well as protect the body and its tissues from harm. 

Best N-Acetyl Cysteine

1. Now NAC

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Now NAC offers free-radical protection for normal immune system function thanks to this stabilized form of cysteine. It’s kosher, non-GMO, soy-free, nut-free, gluten-free, dairy-free, ad egg-free, so it is safe for most diets.

At 600mg per serving, it’s a perfect dose of NAC to get you the results you need. For these reasons, it’s our #1 pick.

2. Integrative Therapeutics – NAC

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This NAC supplement contains no sugar, salt, yeast, artificial coloring or flavoring, or preservatives. It is gluten-free, soy-free, and dairy-free. Integrative therapeutics NAC contains 600mg per serving.

Their ingredients are sourced from partners who share their commitment to purity, potency, and bioavailability. 

3. Life Extension N-Acetyl Cysteine

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Live Extension provides vegetarian capsules of N-acetyl L-cysteine supplements that are designed to be absorbed very quickly. They promote healthy cellular glutathione levels and serve as a liver antioxidant. These are also non-GMO and manufactured in the United States.

Each of these capsules contains 600 mg of this nutrient to support your immune health and protect your cells from free radicals. Life Extension is also certified by the National Sanitation Foundation. Every single one of their batches gets tested for purity and potency before final products are released.

4. Thorne Research NAC

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Thorne’s NAC uses the purest sources available worldwide to create its product. It contains no artificial flavors, colors, preservatives, or sweeteners. and is gluten-free, non-GMO, and dairy-free. Thorne’s NAC also contains, no stearates, no wheat, rye, or barley, and no eggs or nuts. They have no corn, yeast, sugar, or magnesium stearate.

Thorne’s NAC supplements have become a bestselling product because of the well-researched benefits, the pure ingredients, and the clinical research that went into creating the formula and ensuring a high-quality manufacturing process.

5. Jarrow Formulas NAC Sustain

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The Jarrow formula uses a patented bilayer release technology for sustained release and improved effectiveness. It releases 1/3 of the dose instantly for quick absorption and the remainder over time for a longer-lasting result. 

It is a gluten-free, vegan product. This product will raise your blood levels quickly and sustain them over longer periods of time, which assists the antioxidant effect beyond usual capabilities. Most NAC supplements have a half-life of 1.5 hours, and this formula exceeds that.  

6. Nutricost N-Acetyl L-Cysteine

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The Nutricost NAC supplements are made in a GMP compliant facility that has been registered with the FDA. They are non-GMO, gluten-free capsules that have been tested by a 3rd party.

These have been researched extensively and shown to have numerous benefits, including a 50% reduction in acne over time, an aid in quitting smoking, a reduction in liver damage due to alcohol consumption, and more. 

7. Pure encapsulation NAC

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Pure Encapsulations manufactures a line of hypoallergenic, research-based dietary supplements, and their NAC supplement is no different. This product contains a standard 600mg of NAC per serving.

Pure Encapsulations products are free from wheat, gluten, egg, peanuts, magnesium stearate, hydrogenated fat, artificial sweeteners and colors, and other unnecessary fillers. Any product containing ingredients derived from allergens, such as soy, dairy or shellfish is clearly labeled.

8. Designs for Health N-acetyl L-Cysteine

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Designs for Health supplements maintain a very high-quality approach to the selection of their raw materials. They never cut corners or use substandard ingredients. This NAC product is non-GMO, gluten-free, and vegetarian.

They use a science first philosophy that makes sure all of their products are heavily based on the most recent research available.

9. Fresh Nutrition NAC Supplement

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Fresh Nutrition’s NAC supplements have been DNA verified. They are NMR verified and third-party tested for potency and purity, so you can be precise in your dosing without worrying about the quality of ingredients entering your body.

Their supplements are vegan, non-GMO, gluten-free, soy-free, and contain no artificial flavors or colors. They also have all-natural ingredients, with no added chemical preservatives.

10. Doctor’s Best NAC Detox Regulators with Seleno Excell

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The Doctor’s Best supplements are non-GMO supplements that are gluten-free, soy-free, and vegetarian. They are some of the most affordable supplements on the market, and they even contain Seleno Excell to increase the effectiveness of each supplement.

Seleno Excell is a form of organically bound yeast that is high in selenium to increase the bioavailability in the human body. 

How We Rank

When we were looking at the best NAC supplements, there were a few items to consider when selecting the best and ranking them. The first thing we considered was the quality of the ingredients. Every product on this list was sourced from pure and natural ingredients. All of the high ranked supplements, such as Thorne and Nutricost were gluten-free, soy-free, and contained no artificial preservatives or ingredients. Most were either vegan or vegetarian, and non-GMO. 

We also looked at the manufacturing process. High ranking products like Life Extension were produced in manufacturing centers that were held to rigorous standards. Most of them are certified and tested by third parties, and a couple of them are even registered with the FDA as well as the supplement industry’s quality regulation boards. 

The dose was important too. We aimed for our products to have a minimum of 500mg of NAC per serving. Another part of the dosage was how each dose gets delivered. All of these supplements include rapid release formulas that deliver the dose to your system rapidly, ensuring quick results. Jarrow Formula’s even uses a proprietary bi-release system that releases 1/3 of the dose immediately and the other 2/3 overtime to extend the effectiveness of the dose. 

After all this, we determined the top 10 best NAC supplements on the market.


1. NAC contributes to the production of glutathione. Glutathione is considered one of the body’s most critical antioxidants. It acts on every cell in the body and is essential to optimal health and functioning (4).

In fact, researchers suggest that glutathione may even contribute to a longer life (5).

NAC, in combination with glutamine and glycine, helps the body make glutathione. Consequently, glutathione protects the body against age-related diseases, chronic inflammation, and other negative health effects (6).

2. NAC can prevent kidney and liver damage. NAC works to increase glutathione. As well, it acts as an antioxidant on its own. These 2 factors help it prevent liver and kidney damage caused by excessive drinking or environmental factors (7).

NAC is already used to prevent kidney and liver damage in clinics and hospitals. Doctors administer it intravenously to patients along with acetaminophen (8).

In fact, NAC prevents acetaminophen poisoning, which can lead to liver failure or damage (9).

NAC has been studied extensively in preventing liver failure. A 2017 study proved yet again its use in reducing mortality rates amongst those with liver damage (10).

3. NAC can decrease psychiatric disorders and may reduce addictive behavior. Glutamine plays a major role in the reward pathways associated with addiction. NAC, in particular cysteine, works to normalize glutamine levels, interrupting this cycle (11).

It is shown to help in marijuana addiction, cocaine addiction, and even in impulsive behaviors, such as hair pulling (12).

Excess glutamine is also associated with various psychiatric disorders, such as schizophrenia, OCD, depression, and bipolar conditions. Since cysteine works to balance out glutamine levels, it may decrease symptoms of these psychiatric disorders (13, 14).

4. NAC improves the negative effects caused by respiratory conditions. It works to loosen mucus found in the air pathways and to decrease inflammation in the pulmonary system by reducing oxidative stress (15).

In a 2016 study, researchers explored the connection between NAC and COPD, Chronic Obstructive Pulmonary Disease. Patients were given 600 mg of NAC twice a day for 1 year. After 1 year, patients reported a reduction in their symptoms (16).

NAC was further found to reduce airway inflammation in cystic fibrosis patients after just 4 weeks (17).

5. NAC may improve male and female fertility. Various studies have shown the use of NAC for male fertility. A 2016 study reported a 22% increase in partner pregnancy and semen quality with the administration of NAC post-surgery. Surgery was initially required to reduce free radical damage causing vein enlargement (18, 19).

In women, NAC was found to help those that suffer from polycystic ovary syndrome (PCOS). Patients with PCOS were instructed to take 1200 mg of NAC orally for 5 days. Researchers found that NAC significantly improved the ovulation rate, which in turn increased their chances of getting pregnant (20).

6. NAC decreases the risk of heart disease. Heart disease is frequently caused by oxidative stress. Studies have reported the effectiveness of NAC in preventing heart disease by reducing this stress (21).

Another study explored NAC in relation to improved blood flow and vein dilation. It was shown to improve circulation and the efficiency of returning the blood to the heart. In turn, doctors and scientists claim that this can reduce the risk of a heart attack (22).

A 2016 study concluded that NAC improved fatigue, increased exercise tolerance, and reduced heart damage in rats (23).

Heart arrhythmia patients also showed improvements when taking NAC. These patients experienced reduced inflammation and oxidative stress, improving their overall condition (24).

7. NAC can improve brain health and cognitive functioning. As aforementioned, NAC aids in regulating the neurotransmitter, glutamine. This neurotransmitter is associated with many cognitive processes, such as learning, memory, and behavior (25).

Through regulation of this neurotransmitter and the production of glutathione, NAC protects the brain from conditions such as Alzheimer’s Disease, Parkinson’s Disease, and ALS. It is further reported to improve mild cognitive impairments in older adults (26).

NAC may also play a role in reducing negative effects of traumatic brain injuries. In a 2013 study, patients reported a decrease in symptoms including dizziness, headaches, memory loss, and sleep disturbances (27).

8. NAC may help stabilize blood sugar and help diabetic patients. NAC works to replenish antioxidant levels. It also reduces oxidative stress. Consequently, it can protect insulin receptors. This prevents the damage, destruction, and inflammation caused by diabetes (28, 29).

NAC may also play a role in stabilizing blood sugar by reducing inflammation in fat cells. Scientists believe that it may then improve an individual’s insulin resistance (30).

9. NAC could help prevent the flu. During the flu season, germs run rampant. NAC may help protect the body against these germs and their effects. In one 1990s study, researchers gave the experimental group 600 mg, two times a day for 6 months. This group only contracted the flu 25% of the time. The control group, on the other hand, contracted the flu 79% of the time (31).

10. NAC acts to protect the body from pollutants. NAC increases glutathione levels. As a result, the body is better prepared and protected against external toxins. Various studies suggest that NAC protects the body from heavy metal exposure, pesticides, diesel fuel, silica, chemical warfare, and deadly mushrooms (32, 3334, 35, 36, 37, 38, 39).

11. NAC may help treat sleep apnea. A 2011 study explored NAC in relation to treatment for those suffering from sleep apnea. 20 patients received NAC for 30 days. Researchers concluded that oral administration of NAC may prove to be a viable treatment option for sleep apnea patients. It further may reduce sleep apnea patients’ reliance on continuous positive airway pressure (40).

12. NAC could potentially help reduce acne. A 2012 study looked at 100 individuals suffering from acne. With the use of 5% NAC topical gel, participants noticed significant improvements and reduction in their acne symptoms (41).

Another study used a single-blind placebo human trial to test these benefits. The study showed that the NAC caused a 50% reduction in the total lesion counts in acne patients after taking 1200 mg each day for 8 weeks straight (42).

13. NAC may help combat the negative side effects of chemotherapy. This is widely attributed to NAC’s antioxidant effects.

A 2013 study found that NAC injections significantly reduced the negative effects of chemotherapy – specifically cisplatin – on the kidneys and ears (43).

In a 2014 study, NAC helped reduce inflammation and ulcers caused by chemotherapy in leukemia patients (44).

14. NAC may help protect hearing and ears. Again, researchers indicate that this may be attributed to NAC’s powerful antioxidant abilities.

A 2014 study explored NAC in relation to noise-induced hearing loss. The study was conducted using 48 participants who were exposed to continual noise during their working hours. 3 groups were observed. The first group was given 1200 mg of NAC per day. The second group was given 200 mg of ginseng per day.

And the third group had no supplementation assigned. After 14 days, researchers concluded that ginseng and NAC helped reduce hearing loss associated with occupational noise. However, the NAC group was shown to have the most positive effects (45).

15. NAC may help break an addiction to nicotine. In one study, the subjects who were addicted to nicotine that received 2400 mg of N-acetyl cysteine for 4 weeks saw a reduction in the frequency of cigarette smoking after just 2 weeks as compared to those given a placebo (46).

16. NAC may help with alcohol use. Having NAC in your system has been shown to increase liver function and help your system process the alcohol. Taking a NAC supplement before drinking can help to reduce liver damage due to alcohol consumption.  Another study assessed the mitochondrial structure of liver tissue in rodents. This showed that NAC seemed to prevent hermetic responses to alcohol. It has even helped with hangovers (47).

Side Effects

1. NAC can cause IBS like symptoms. High amounts may cause nausea, vomiting, diarrhea, and constipation (48).

2. Aerosol NAC can cause swelling in the mouth, runny nose, drowsiness and chest tightness.

3. NAC may interfere with blood clotting. Since NAC can impact the platelets and reduce coagulation, people with bleeding disorders or taking blood-thinning medications should not take NAC (49).

4. NAC can decrease blood pressure. Low blood pressure — also called hypotension — may cause symptoms of headache, dizziness or fatigue. If you feel dizzy, remain seated until this sensation passes to prevent further injury from falling down or tripping.

5. NAC may cause an allergic reaction in certain individuals. A severe allergic reaction, called an anaphylactoid reaction, may occur after initial treatment with NAC supplements. An anaphylactoid reaction may result in severe breathing problems, difficulty swallowing, facial swelling, hives, weakness, dizziness or pale skin. Seek emergency medical care if you exhibit any of these symptoms after taking a NAC supplement.

6. NAC may cause fevers, runny nose, drowsiness and fatigue, and clamminess. Because it can also cause coughing, wheezing, bronchial irritation, and shortness of breath, it is not recommended for use by people who have asthma and other respiratory problems. More serious side effects may include chest tightness, bleeding, and bronchoconstriction. If you experience any of these serious side effects, stop taking this supplement immediately and consult your doctor. 

Recommended Dosage

The accepted daily supplement recommendation is 600–1,800 mg of NAC via IV, aerosol or powder form (50).

However, it can go as high as 2400mg/day. The dosage is often split up into 2-3 doses.

Some studies the benefits of NAC for reducing addiction and mental health issues used doses closer to 3000 mg/day. For general wellness or gut health, 600 mg a day is the typical dose.

A maximum safe dose of NAC has yet to be determined.


What is N acetylcysteine good for? As a prescription drug, doctors use NAC to treat acetaminophen overdose. It may also help break up mucus in people with some lung diseases, like chronic bronchitis. As a supplement, some people use NAC to try to protect the liver. There’s evidence it can help prevent bladder or neurologic damage caused by some drugs.

Is NAC safe to take daily? Yes, oral NAC supplements are safe and generally well tolerated.

Is N acetylcysteine over the counter? In addition to prescription availability, NAC is commercially accessible as an over-the-counter product and has been safely used as a supplement in humans for years (NAC is relatively rare in food).

What are the side effects of taking NAC? NAC is likely safe for adults when provided as a prescription medication. However, high amounts may cause nausea, vomiting, diarrhea, and constipation. When inhaled, it can cause swelling in the mouth, runny nose, drowsiness and chest tightness.

What’s the difference between NAC and glutathione? It’s simple, NAC is the precursor of the antioxidant glutathione.

Should NAC be taken on an empty stomach? Yes, taking it on an empty stomach is ideal. Like other amino acid supplements, NAC should be taken either 30 minutes before, or two hours after, eating to avoid competing with protein for absorption.

Is NAC good for your liver? N-acetylcysteine is so protective to the liver that it is commonly administered to save patients who have overdosed on Tylenol from liver failure—it’s the only known antidote. NAC is a potent precursor of glutathione, a powerful antioxidant.

Can NAC help with high blood pressure? In animal studies of hypertension, NAC not only reduced blood pressure but also was effective at reducing oxidative stress and improving antioxidant capacity.

Is NAC good for chronic obstructive pulmonary disease (COPD)? Yes, NAC is an antioxidant supplement that has shown promise in some studies but not in others. NAC is a robust treatment for COPD that reduces phlegm and cough, thins mucus, and eases expectoration. It’s said to decrease the deterioration of lung function.

Does NAC lighten skin? Glutathione has been known to lighten the skin as since NAC is a precursor to glutathione, NAC can also be responsible for some skin lightening.

Can NAC or glutathione deficiency cause death? Though a deficiency does not cause death directly, its absence could make you more prone to this outcome. As glutathione regulates many of the body’s functions and manages several different cell types, a lack of this can create larger health issues

Can I drink alcohol while taking NAC? Yes, you can drink alcohol however it is counterintuitive as alcohol depletes the liver’s glutathione stores.

Is glutathione the same as NAC? No, NAC is a precursor to glutathione. It helps replenish and create glutathione.

Does NAC increase glutathione? N-acetyl L-cysteine helps to replenish intracellular glutathione, a vital cellular antioxidant.

Who would benefit from a NAC supplement? In general, NAC or glutathione can provide benefits to multiple people with various ailments. Both men and women would benefit from taking daily doses of this supplement. Those suffering from more serious illnesses will want to consult with their physician before beginning use continuously.

Does NAC help with weight loss? Not directly, however, NAC may play a role in the treatment of diabetes mellitus due to its ability to improve insulin sensitivity and reduce fasting blood insulin levels.

Does NAC help with hangovers? The best way to help prevent possible liver damage is to take an NAC hangover supplement before drinking alcohol (NAC and alcohol). This will assist in the production of glutathione which will help break down the toxic acetaldehyde.

My NAC supplement has a terrible smell like rotting eggs. Does that mean it has gone bad, and will I smell like that if I take it? That smell is a normal byproduct of the supplement. NAC is a very rich source of sulfur, which is a mineral that is necessary for making vitamins, hormones, and tissue. Unfortunately, sulfur also smells like rotten eggs and that means your NAC supplements do, too. It is extremely unpleasant and may make it more difficult for you to take the supplement, but it has not gone bad. The good news is that taking it will not cause you to smell this way. Unlike other supplements, this one does not release its stench in your sweat glands, so you can relax. While the supplement stinks, it won’t cause you to stink, too. 

Since NAC needs to get to the intestine to be effective, will gastric acid render the supplement useless? No, this will not happen. Our bodies are able to make glutathione. When you take it orally, glutathione isolate may be broken down by gastric acids, but NAC bonds to other proteins, so it gets absorbed into your system. It is treated as an amino acid, and therefore highly effective and easily able to be processed without being eliminated by gastric acids. 

How large are the capsules? The size varies from manufacturer to manufacturer. It also varies based on dosage. In general, most of them are the size of standard pills and should be relatively easy to swallow. These would be roughly an inch long, ad less than a quarter-inch in diameter. They are essentially veggie capsules. 

Is NAC vegan? Whether your NAC supplement is vegan or not depends on what brand or manufacturer you buy from. Some capsules use animal by-products or meat. All of the supplements found in our rankings are vegetarian, and half of them are vegan. Be sure to check that you have chosen a vegan brand before purchasing your supplements.

Can glutathione, produced by NAC, cause liver damage? No, in fact, it does the opposite. Glutathione has been shown to improve protein, enzyme, and bilirubin levels in the blood of individuals with alcoholic and nonalcoholic chronic fatty liver disease. A study reported that glutathione was most effective when given to people with fatty liver disease intravenously, in high doses.

Is NAC gluten-free? Yes, all of the supplements on our list are gluten-free, soy-free, and non-GMO. In fact, it is very unlikely that you will run into a NAC supplement that contains gluten. If you stick to veggie capsules, you should be safe. If you are ever in doubt, be sure to check the ingredients on the bottle you are about to purchase to be safe.

What is the shelf life for a bottle of NAC supplements? Each supplement bottle will have a different recommended shelf life based on the manufacturing process and ingredients. If you choose a supplement that doesn’t use preservatives, it will have a much shorter shelf life. That being said, the average shelf life for a typical NAC veggie capsule is around 2 years from the date it was manufactured. These dates are usually printed on the bottle if an expiration date is not printed. If you store your supplements in a cool, dry place you can probably significantly extend the shelf life of your NAC supplements. Once you have opened your NAC supplements, the shelf life is around 6 months. Make sure to note the date you opened them, and throw them away if you have not consumed all the capsules within the 6 months.  

Can I cut the pill in half? If your supplement is a capsule, you will not be able to cut it in half to consume it, because the contents will spill out of the capsule. If you have a tablet, you can cut it but keep in mind that if you are using a sustained-release or time-release capsule, you will reduce the effectiveness of that release. The dose itself will still work as if they were normal quick absorption doses, but the time-release works because of the coating, ad breaking the tablet means unsealing the coating that sustains the release.

Is there a major difference between the different brands of NAC supplements? All of the supplements are designed primarily to dose you with NAC. The main and active ingredients should be pretty standard from company to company. The difference comes in dose sizing. Capsules may contain different amounts, from 400 to 600 to 900 or more mg per capsule. Make sure that you are taking the dose you want to, and look into how many times per day you need to take the supplement based on the dosing instructions.

Ingredients may also change from company to company, though the majority of NAC manufacturers are non-GMO, gluten-free, soy-free, dairy-free, nut-free manufacturers. Some of them may use sugars to mask the flavor of the sulfur found in NAC tablets, while others will not use any artificial flavoring. A few companies will use different ingredients for their type of supplement. There are powders, tablets, and capsules so each of these different types of dosing forms will have different ingredients. Different formulas will also contain different ingredients. The time-released doses will have additional ingredients in their coating to make sure the dose gets released over time rather than all at once.

Some companies may even use preservatives (artificial or natural) to prolong the shelf life of their products. Even among the capsules, some companies use a vegetable-based capsule that contains some animal byproducts and others use completely vegan veggie capsules instead. 


NAC is an exceptional supplement, particularly for its ability to promote glutathione production within the body. It also has the capacity to rebalance the neurotransmitter, glutamine, which in excess contributes to an array of cognitive and mental impairments. NAC also contributes to reduced oxidative stress and inflammation throughout the body. As a result, it protects the body against various ill health effects and diseases.

NAC may further protect the body from external factors, such as pollutants, toxins, and germs, as well it may improve fertility in men and women. According to most studies, the most common dosage of NAC falls between 800-2400 mg with a frequency of 2-3 times per day.

It’s important to consult with your family doctor before taking any new medication. They know your medical history best and can make the proper recommendations for you and your specific situation.  

For Healthtrends #1 N-Acetyl Cysteine recommendation, click here.

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