What Is N-acetylcysteine?
N-acetylcysteine (NAC) is a supplement form of of the amino acid cysteine. You get cysteine by eating high-protein foods such as beef, chicken, eggs, and whole grains. Your body can also make some cysteine by combining two other amino acids: serine and methionine. But if you're low on these two amino acids, then you may need to take a cysteine supplement. Your body will convert NAC to cysteine.
N-acetylcysteine Benefits
The main benefits of NAC come from the supplement’s antioxidant and anti-inflammatory properties. Antioxidants are compounds that help fight disease in your body. Anti-inflammatories reduce swelling and irritation in your body's tissues.
While researchers don’t yet understand exactly how NAC works to promote health, they do know that it helps your body make more glutathione, a potent antioxidant that helps to get rid of cell-damaging free radicals.
Free radicals are also called reactive oxygen species (ROS). ROS can damage your DNA, a process known as oxidative stress. In general, reducing oxidative stress with antioxidants like NAC can help lower your risk of certainhealth conditions, such as heart disease, diabetes, and infertility.
Proven benefits of NAC
At this time, there is only one scientifically proven benefit of NAC:
Treatment of acetaminophen overdose.By boosting levels of glutathione, NAC speeds up the breakdown of acetaminophen. You may be able to prevent liver or kidney damage if you get treatment within 8-10 hours of acetaminophen poisoning.
Go to the hospital if you or a loved one takes too much acetaminophen. A health professional may need to give you a high dose of the supplement through a vein in your arm.
Potential benefits of NAC
Researchers are still gathering evidence to support the use of NAC in these areas:
Treatment of chronic lung diseases. NAC supplements, particularly the kind you breathe in, may lessen inflammation in your airways. This might reduce the number of future flare-ups caused by COPD and improve lung function, but not all studies have found these results.
The supplement may also help to decrease the severity of wheezing and coughing in some people with ongoing bronchitis. More studies are needed to confirm these results.
High-dose NAC (1,200 milligrams per day) may also help lower inflammation, break up biofilms where germs live, and lessen damage caused by oxidative stress in the lungs and airways of people with cystic fibrosis, when used alone or with other medications.
Improve liver and kidney function. Your liver and kidneys flush drugs and other toxins out of your body. NAC supplements can speed up this breakdown process and may help your organs work better if you have liver or kidney disease. But more research is needed to know for sure.
Viral suppression. There aren’t many studies on NAC and the immune system, but current research suggests that it and glutathione may help to improve immune function in people with HIV. Some research shows that the supplement may help to suppress HIV-1 reproduction. But more research is needed to know if NAC has a big benefit for people with HIV/AIDS.
Test tube studies also show that NAC may stop the flu virus from replicating. In one 6-month study, people who took 600 milligrams of NAC twice a day reported fewer flu symptoms than people who didn’t take the supplement.
Balance blood sugar in people with insulin resistance. Research suggests the NAC may help to improve insulin resistance – when your body doesn’t respond to insulin, the hormone that keeps your blood sugar in check.
There’s some evidence the supplement may be particularly helpful for people with insulin resistance who have polycystic ovary syndrome (PCOS), a hormonal condition that interferes with periods and the ovaries.
Researchers have found little evidence that NAC can help people with type 2 diabetes gain good control over their blood sugar or increase their sensitivity to insulin.
Boosts brain function. NAC helps to refill glutathione levels in the body. It also aids in controlling a neurotransmitter called glutamate and can lessen inflammation and damage caused by oxidative stress. These functions may help protect cells needed for brain health, which may benefit people with neurodegenerative conditions such as Alzheimer’s and Parkinson’s diseases.
Improves treatment for mental health conditions. Researchers have found mixed results when it comes to how well NAC works to treat psychiatric disorders, but there’s promising evidence that the supplement may change the brain and nervous system in a way that helps lessen symptoms associated with:
- Major depressive disorder
- Schizophrenia
- Bipolar disorder
- Posttraumatic stress disorder (PTSD)
- Obsessive-compulsive disorder
- Trichotillomania (hair pulling)
- Substance use disorders
Some studies show that the supplement may help ease symptoms of withdrawal, including a strong urge or craving to take drugs. This may lessen the chances of relapse in people who’ve stopped misusing substances such as stimulants, cannabis, tobacco, and alcohol.
N-acetylcysteine for skin picking. NAC may improve symptoms of excoriation disorder, also called skin-picking disorder (SPD). One study found that people with SPD who took 1,200-1,300 milligrams of NAC daily for 3 months reported fewer SPD behaviors than those who didn’t take the supplement.
Lowers heart disease risk. Studies on human cells show that, when combined with green tea, NAC may help lessen damage caused by LDL cholesterol. LDL is the “bad” kind of cholesterol associated with heart disease.
Helps with fertility. NAC may improve fertility in people of all sexes. One study found that men and people assigned male at birth who had trouble with infertility improved their sem*n quality when they took NAC alone or with selenium.
NAC may also helpwomen and people assigned female at birth ovulate regularly, particularly if you have infertility associated with a condition like PCOS.
Other uses of N-acetylcysteine
More research is needed, but there’s a small amount of evidence that NAC may:
- Prevent cell damage that may turn into cancer
- Lessen side effects from cancer treatment
- Control inflammation and reduce asthma attacks
- Dissolve blood clots
- Ease symptoms of Sjögren syndrome, an autoimmune condition that causes dryness
- Be useful in treatment of inflammatory conditions like lupus or rheumatoid arthritis.
Researchers continue to study the benefits of NAC on cancer and its treatment, including triple-negative breast cancer, colon cancer, liver cancer, and lung cancer in smokers. But there isn’t strong enough evidence to say that the supplement can prevent cancer.
Ask your doctor if NAC is safe for you to take if you have cancer.
N-acetylcysteine Side Effects and Risks
N-acetylcysteine can provide health benefits. But like all medications and dietary supplements, NAC may come with risks.
The most common side effects of NAC include:
- Upset stomach
- Nausea or throwing up
- Diarrhea
- Fatigue
- Eye irritation
- Itching or rash
- Skin swelling
- Wheezing
Less commonly, NAC may cause:
- Low blood pressure
- Increased asthma symptoms
- Chest tightness or numbness around your mouth (if you inhale it)
- Headache
- Life-threatening allergic reaction (anaphylactic shock)
NAC may also:
Raise levels of hom*ocysteine. Too much of this amino acid may boost your odds of cardiovascular disease and its complications, such as heart attack or stroke. Your doctor can let you know if this is something you’d need to worry about.
Slow blood clotting.NAC can make it harder for your blood cells to stick together. This may help break up blood clots or cause you to bleed easier.
Interact withmedications.Talk to your doctor first before you take NAC supplements. They may not be safe with the following medications:
- Immunosuppressants like azathioprine, cyclophosphamide, and prednisone
- Medication for chest pain (angina), including isosorbide and nitroglycerin
- Antifungal drugs like oxiconazole
NAC may not work as well when paired with certain antibiotics (oxytetracycline, tetracycline, and trypsin) or activated charcoal. But if you do need to take two drugs together, your doctor can let you know if you need to adjust the dose of your supplement.
Who should not take N-acetylcysteine?
Ask your doctor which supplements are right for you, but NAC may not not be safe for people who:
Bleed easily.NAC may raise your odds of bleeding problems if you have a bleeding disorder such as hemophilia or you take blood-thinning drugs.
Have cystinuria.This disorder causes you to pee out a lot of cystine, which is related to cysteine. People with cystinuria are naturally more likely to form cystine kidney stones. These are hard deposits made of minerals and salts that buildup.
Take nitroglycerin. NAC can widen your blood vessels. This may further lower your blood pressure and cause serious headaches if you take nitroglycerin regularly.
N-acetylcysteine Dose
Most people don’t need to take NAC to stay healthy, so there aren’t any specific dietary recommendations. That’s because your body can typically make enough cysteine from the protein-rich foods you eat.
NAC isn’t in food, but supplementation can help boost cysteine levels so you can make more glutathione.
NAC comes in the following forms:
- Solution to inhale
- Intravenous injection
- Dissolvable tablets
- Pills
- Powder
- Liquid
These supplements have low bioavailability, which means they are not well-absorbed by the body at low doses. When used in medical treatment, the typical recommendation for NAC is between 600 and 1,800 milligrams.
In some studies, researchers have people take up to 3,000 milligrams a day, divided into two or three doses.
When to take NAC
The dose and frequency depend on why you’re taking NAC in the first place. Your doctor will let you know what’s safe and effective for your health condition.
Excessive doses of NAC (7 grams or more) can damage your cells. If you take very high amounts over a short amount of time, you could damage your kidneys or even die.
Takeaways
N-acetylcysteine (NAC) is a medication and dietary supplement with anti-inflammatory and antioxidant properties. It’s used most often to treat acetaminophen overdose. NAC-based drugs can also break up mucus in the lungs and airways. This helps people with chronic respiratory diseases breathe easier.
NAC supplements may ease symptoms of mental health conditions such as depression, schizophrenia, and substance use disorders. There’s ongoing research in this area.
Talk to your doctor first before you take NAC. These supplements may not be safe to take with certain medications, including those used to treat chest pain.
