A Guide to N-Acetylcysteine: 7 Possible Use - GoodRx (2024)

N-acetylcysteine, also known as acetylcysteine or NAC, is a compound that’s naturally found in some fruits and vegetables. It has anti-inflammatory, antioxidant, and mucolytic (mucus thinning) properties.

NAC is available as both a prescription medication and an over-the-counter (OTC) supplement. Prescription-only NAC comes as a liquid that can be inhaled, swallowed, or injected into a vein (IV). These products have specific FDA-approved uses. OTC NAC supplements are less regulated. Some people might take them for mental health benefits or to help treat substance use disorders.

So what can NAC actually be used for? Here we’ll review seven common acetylcysteine uses and the evidence behind them.

1. Treats acetaminophen (Tylenol) overdose

Prescription NAC is most often used to treat acetaminophen (Tylenol) overdose. These overdoses are more common than you may think, and about half of them are accidental. That’s because many different OTC products can contain acetaminophen. So it can be easy to take more acetaminophen than you realize.

When you take too much acetaminophen, a toxic substance called NAPQI builds up in the body and damages your liver. When given early enough (within 8 hours), NAC binds and removes NAPQI from the body, which helps prevent liver damage.

The IV and oral forms of NAC are both effective options, but have different side effects to consider. The oral liquid has a rotten-egg smell and taste that can make it difficult to swallow. The IV infusion can cause red, flushed skin and allergic reactions in some people.

The best way to prevent acetaminophen overdose is to carefully check the labels of any OTC medications you take to look for duplicate ingredients. And don’t take more acetaminophen than recommended. If you or someone you know has taken too much acetaminophen, get help by calling Poison Control at 1-800-222-1222, or seek emergency care.

Keep in mind: Treating an acetaminophen overdose requires the expertise and supervision of a healthcare professional. This condition can be life-threatening if it isn’t treated properly. So you shouldn’t try to treat an acetaminophen overdose on your own with OTC NAC supplements.

2. Helps with chronic lung conditions

The inhaled form of NAC is FDA approved to treat symptoms of chronic lung conditions such as emphysema, chronic obstructive pulmonary disease (COPD), and cystic fibrosis.

These conditions can cause thick mucus to build up in your airways, which makes it harder to breathe. Inhaling NAC into the lungs can help break down this thick mucus and improve breathing.

Oral NAC supplements have also been studied for chronic lung conditions. Study results are mixed, but most didn’t find any significant benefits of oral NAC supplements on these lung conditions. If you’re considering taking an NAC supplement for your chronic lung condition, it’s best to discuss it with your provider first to make sure it’s a safe option for you.

Good to know: Acetylcysteine is a common ingredient in OTC cough medications outside the U.S. You may see claims that NAC supplements can help with cough or congestion from conditions like the common cold. But recent evidence is limited that NAC is effective for this use. These claims are largely based on a series of older studies that showed NAC may improve cough symptoms in children after 6 to 7 days of treatment. Most other OTC cough treatments work much faster than this, so NAC’s benefit in a real-world scenario seems minimal.

3. May improve mental health

NAC has a variety of effects that may help treat mental health conditions. Its antioxidant effects may help lower stress, and its anti-inflammatory effects may help with mental health symptoms associated with inflammation.

NAC may also affect chemical messengers, such as glutamate and dopamine, in the brain. These chemicals play a role in mental health conditions such as depression, bipolar disorder, and schizophrenia.

Results of studies on NAC for mental health conditions are mixed. Some show that NAC may improve symptoms of depression, schizophrenia, and obsessive compulsive disorders. But others show no benefit from NAC for these conditions, or don’t look at how long the improvement lasts.

More studies are needed to understand the impact of NAC on mental health. If you’re interested in trying an NAC supplement for your mental health, make sure your provider OKs it first.

4. May help treat substance use disorders

The chemical messengers glutamate and dopamine also play a role in substance use disorder. Studies on NAC for substance use disorders involving cocaine, cannabis, and nicotine show that it may help reduce cravings. This can help prevent relapses and support other substance use disorder treatments.

Keep in mind that NAC hasn’t been shown effective at treating substance use disorder on its own. And most studies that show NAC’s ability to reduce cravings are small. It’s best to stick to proven therapies and medications when it comes to treating substance misuse. Your provider can help you find the right treatments for your specific needs.

If you or someone you know struggles with substance use, help is available. Call SAMHSA’s National Helpline at 1-800-662-4357 to learn about resources in your area.

5. Supports brain health

NAC raises levels of a chemical called glutathione in the brain. Glutathione is an antioxidant that plays a key role in how your cells function.

Low glutathione levels are associated with several brain-related conditions, such as Parkinson’s disease, Alzheimer’s disease, and multiple sclerosis. So it’s possible that NAC’s effect on glutathione may help improve symptoms or prevent the progression of these conditions.

Early studies show that NAC may be beneficial for these conditions when added to other medications. And more research is in progress. It’s unlikely that NAC will be a treatment for these conditions on its own, but may help support existing treatments.

6. Helps protect your heart

NAC may be helpful for certain heart conditions. NAC’s antioxidant properties seem to lessen the stress on the heart caused by some health conditions.

Several trials have shown that IV NACduring a heart attack can help reduce heart damage and chest pain when combined with nitroglycerin. NAC may also reduce the risk of developing atrial fibrillation (an irregular heartbeat) after heart surgery. And some small studies show that NAC may improve heart function for those living with heart failure. Other research shows additional benefits of NAC in heart failure, but these studies were in animals only.

More long-term human studies are needed to fully understand NAC’s role in managing or preventing certain heart conditions.

7. May boost fertility

Researchers have found positive effects of NAC on male and female infertility as well as pregnancy outcomes. Specifically, NAC may help:

• Increase sperm production and quality in men

• Improve ovulation and pregnancy rates women with unexplained infertility or polycystic ovary syndrome (PCOS) when taken along with clomiphene citrate (Clomid)

• Increase the live birth rate in those with a history of early pregnancy loss when taken along with folic acid

• Manage gestational diabetes and prevent it from causing heart problems in a growing fetus (only shown in animal studies thus far)

• Manage preeclampsia symptoms

Many fertility-related studies are small, so more research is needed to understand how NAC may impact pregnancy outcomes. Your provider can help determine if taking NAC may improve your fertility based on your medical history.

Is N-Acetylcysteine safe to take?

NAC tends to be a safe and well-tolerated supplement. Common NAC side effects include nausea, diarrhea, and heartburn. Inhaled NAC may also cause a cough for some people.

It’s best to avoid taking NAC if you’ve had an allergic reaction to it in the past. It’s also a good idea to get your provider’s OK before starting an NAC supplement. While the research on NAC is promising for various health conditions, most studies haven’t evaluated the safety and benefit of taking NAC long-term.