Everything You Need To Know About N-Acetylcysteine (NAC)

N-Acetylcysteine molecule drawn out

We all want to be happier and healthier, but truth be told, most ‘general health’ supplements are a waste of time and money.

One supplement that may actually be worth adding to your daily regimen, however, is N-Acetylcysteine, or NAC for short.

NAC is nothing new, but research is ongoing, and new benefits are still being discovered.

Typically, you’ll find it in supplements that claim to promote liver health and detoxify your body, but there are plenty of other reasons you might want to consider supplementing with NAC as well.

Out of all the ‘general health’ supplements I’ve researched, NAC is one of the few which has earned a permanent spot in my daily supplement regimen and in this article I’m going to tell you why.

We’ll cover everything you need to know about NAC, including:

  • What it is
  • What it does
  • The benefits
  • Dosage
  • Side effects/safety

So, if you’re ready to learn all about this unique amino acid and how it can potentially benefit you, let’s dive right in…

What Is N-Acetylcysteine (NAC)?

N-Acetylcysteine (NAC) is a highly bioavailable form of the sulfur-containing amino acid, Cysteine.

NAC chemical molecule

Cysteine is one of the two sulfur containing amino acids that make up our genetic code, the other being Methionine.

It supports a wide variety of processes throughout the body, many of which are related to detoxification, reducing inflammation, and fighting oxidation.

NAC is simply an efficient, highly bioavailable form of Cysteine, so it has powerful anti-oxidant and anti-inflammatory properties which make it useful as a supplement.

NAC Supplementation is believed to offer a wide range of health benefits.  We’ll talk about those benefits in depth in just a minute but first we need to take a moment to understand how NAC works in the first place.

How Does NAC Work?

The most common reason people supplement with NAC is to boost Glutathione levels.

Glutathione is a unique molecule which is often referred to as the body’s ‘master antioxidant’.  It is heavily involved in detoxification processes and provides general antioxidant defense throughout the body.

Glutathione is produced endogenously (by the body) from a combination of the amino acids L-Cysteine, L-Glycine, and L-Glutamic Acid.

Cysteine is the rate-limiting factor, though.

By providing the rate limiting factor (Cysteine), NAC supplementation can directly increase Glutathione production.

Interestingly, research shows that oral Glutathione supplements have poor bioavailability so NAC is actually a far better supplement for the purposes of boosting Glutathione levels.

Many of the benefits associated with NAC supplementation are simply the result of increased Glutathione levels, but research indicates it has direct free radical scavenging properties as well.

What Are The Benefits Of NAC Supplementation?

Whether through increasing Glutathione or exerting it’s own direct antioxidant effects, N-Acetylcysteine appears to have numerous benefits.

NAC Protects The Liver

Due to the fact that Glutathione is particularly active in the liver, many of the studies regarding the general health impact of NAC supplementation have focused specifically on how it impacts liver health.

N-Acetylcysteine has been shown to reduce acetaminophen (Tylenol) toxicity in multiple studies.

Research also indicates it can improve liver health in people with liver disease as well as those recovering from liver transplants.

There’s even some preliminary research (in mice) indicating NAC can reduce the negative impact of alcohol on the liver as well.

When you step back and take a look at the research as a whole, it’s pretty clear that NAC is beneficial for liver health.

There’s really no doubt about it.

NAC Protects Against Heavy Metal Toxicity

Another key area of investigation has been the way in which NAC interacts with heavy metals.

Research has confirmed that N-Acetylcysteine supplementation is capable of reducing circulating lead and other heavy metals.

It is so effective at doing this that it’s regularly used by doctors to treat heavy metal poisoning.

NAC works partially by increasing Glutathione but also by acting as a metal chelator.

That is, a substance that can attach itself to metals, rendering them inactive and then eliminating them from the body.

Chelation is one of the ways the body can rid itself of toxic heavy metals like lead, cadmium, mercury, and arsenic.

These metals are in no way vital to our survival and while the body can tolerate tiny amounts of them, high levels can cause all kinds of health detriments, from interfering with the absorption of other nutrients to death.

NAC is quite an effective metal chelator.

NAC May Enhance Exercise Performance

Although not well-known as a performance enhancing supplement, NAC has actually been shown to enhance exercise performance in multiple studies.

Research has confirmed that it can reduce muscular fatigue, but exactly how it works remains a mystery.

While NAC does appear to be effective, the dosage required to achieve these benefits is quite high.

In recent years, we’ve seen a few pre-workout supplements use NAC, but due to it’s bitter, sulfuric taste, it’s difficult to make palatable.

For that reason, pretty much all pre-workout supplements that contain NAC are extremely under-dosed, so performance enhancement is far from guaranteed.

If it’s better muscular endurance you’re after, it’s probably best to just buy your NAC separately and dose it properly.  Of course, you could always just use a more proven endurance enhancer like Citrulline as well.

NAC Helps Treat Addiction

This may seem a little odd, but NAC is also used in the field of psychiatry as a potential treatment for addiction.

It has been shown to reduce marijuana cravings, cigarette smoking, and even help manage cocaine addiction!

It’s unclear how exactly it’s doing this, but plenty of studies have confirmed an anti-addictive property of NAC with multiple different substances, from mildly addicted (Marijuana) to ultra-addictive (Cocaine).

It definitely works.  It’s just the ‘how’ that we don’t quite fully understand yet.

Obviously there must be more at work than the usual free radical scavenging, but the inner workings of addiction are tricky.  It may be years before we figure out how exactly NAC is able to exert its anti-addictive effects.

The good news is that if you’re trying to get a handle on some kind of addictive behavior, NAC is a cheap, affordable option which may actually help.

NAC Helps With Stress And Anxiety

It may seem odd that a non-psychoactive substance could have an impact on stress and anxiety, but let me explain…

NAC doesn’t directly reduce stress levels or anxiety.  It simply reduces the occurrence of certain manifestations or symptoms.

Supplementation with NAC has been shown to reduce nail biting and skin picking associated with anxiety disorders.

For people with certain anxiety disorders that exacerbate these types of behaviors, it makes for a worthwhile first line of defense.

N-Acetylcysteine isn’t a replacement for anxiety drugs like Alprazolam or Etizolam, but can be used as an adjunct therapy for treating certain symptoms of anxiety.

It’s not clear at all how it works, though.  Only further studies will tell!

NAC May Help With Certain Aspects Of Autism

Research shows that NAC supplementation is capable of altering Glutamate activity in the brain.

Since Autism is associated with abnormal Glutamate (Glutamic Acid) activity in the brain, it makes sense that NAC has been investigated as a possible component of treatment.

Studies show that NAC can reduce irritability in children with Autism.

Of course, this doesn’t mean NAC can ‘treat Autism’.  It simply shows that NAC can be useful as an adjunct therapy in some cases.

NAC May Improve Skin Health

Pin-pointing the cause of acne can be tricky, but recent research shows free-radical damage may be a major culprit in some instances of extreme acne.

Since NAC is known to be a powerful free-radical scavenger, it makes sense that it has been investigated clinically as an acne treatment.

One study found that a combination of NAC, Milk Thistle, and Selenium was able to reduce the severity of acne in human subjects.

Unfortunately, this is the only study we currently have to go by and, because it involved other supplements as well, the benefits observed can’t be solely attributed to NAC.

That said, given that the antioxidant properties of NAC are well-established, it’s not much of a stretch to suggest that NAC can beneficially impact skin health, at least to some degree.

NAC Dosage

The clinical dose of any supplement is simply that dose at which it has been proven effective in scientific studies.

For a supplement like NAC, where there are multiple reasons to use it, it’s actually more of a ‘clinical range’.

Studies have used anywhere from 600-2400mg/day with some studies using several grams per day, depending on the use case.

For general health and detoxification purposes, 600-1200mg/day is a good place to start.

For treating addiction, 1200-2400mg/day is effective.

For enhancing muscular endurance, anywhere from 1200-6000mg/day.

There’s no scientific consensus on whether timing has much of an impact, but it makes sense to split up whatever dose you’re taking throughout the day.

So, for example, if you’re taking 2400mg/day, you could take 800mg 3 times per day, with meals.

Are There Any Side Effects With NAC?

N-Acetylcysteine is remarkably safe as a dietary supplement.

This makes sense, considering the fact that Cysteine itself is found in many of the foods we eat and NAC is just a better version of it.

However, taking too much at a time can potentially result in things like:

  • Upset stomach
  • Nausea
  • Skin-Rash
  • Drowsiness
  • Constipation

These side effects are rare, but they’re worth being aware of.

For the average person, NAC is perfectly safe and unlikely to cause any discernible side effects.

Spreading out your daily dosage and consuming it with meals is the best way to avoid things like nausea, upset stomach, and constipation.

What To Expect With NAC

It’s important to understand that NAC isn’t some magical cure-all supplement that will instantly make you healthier, feel better, or perform better.

Given all the research, it makes sense to supplement with NAC as a general health supplement, but if you’re expecting some sort of miracle, you’ll almost surely be disappointed.

In fact, aside from the areas of mental health and skin health, most of the benefits NAC provides can’t be directly observed.

This is one of those supplements that you just kind of take because you know it’s good for you, not because it offers some sort of instant gratification.

Choosing The Best NAC Supplement

There are a ton of NAC supplements out there.  Unfortunately, they’re not all equal.  Most NAC supplements are never third party tested for things like:

  • identity
  • purity
  • contaminants

So it’s basically impossible to know for sure that you’re getting a high quality product before you actually buy it.

Pure NAC has a very distinct sulfur-like smell to it.  If you’re NAC supplement smells like sulfur, that’s actually a good thing!

I wish I could vouch for a specific brand, but I can’t in this case.

Head on over to Amazon, read reviews, and select accordingly.  I’ll let you know as soon as Singular Sport releases an NAC supplement (that you can DEFINITELY trust).

My Personal Take On NAC

I think NAC makes sense as a general health supplement.  I take 1200mg/day.

  • 600mg with breakfast
  • 600mg with dinner

I wouldn’t say the benefits are super noticeable (my skin may be a little clearer), but there’s more than enough research to conclude that a little NAC everyday is good for you, and that’s good enough for me.

I routinely suggest NAC supplementation to people who drink a lot because of it’s liver-cleansing properties as well as to anyone who drinks detox tea, since NAC actually is the closest thing you can have to a general ‘detox supplement’.

If you’re concerned about your liver health for one reason or another, it makes sense to stack NAC with supplements like TUDCA and Milk Thistle, which may be complimentary in regards to promoting liver health.

The Bottom Line On N-Acetylcysteine (NAC)

N-Acetylcysteine has a wide array of potential and proven benefits.  Some have more research behind them than others, but overall, it’s a supplement that a lot of people may derive benefit from.

It’s one of those supplements that just makes sense to take on a daily basis, for general health purposes.

Try taking 600-1200mg/day with meals, and make sure you get your NAC supplement from a reliable brand you can actually trust.

Just keep in mind that you really can’t trust most supplements.

Choose wisely!

What’s Your Take On N-Acetylcysteine (NAC)?  Comment Below…

I’m Matt Theis, founder of SuppWithThat, Momentum Nutrition, and Singular Sport. I created SWT to separate the science from the hype and publish accurate, research-based information on supplements. If you like what I have to say here, feel free to check out my supplements at and

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