NAC (N-acetylcysteine)

What Is It?

Produced by the body, N-acetylcysteine (commonly called NAC) is a form of the amino acid cysteine. Because it enhances the production of the Enzyme glutathione, one of the body’s powerhouse antioxidants, NAC can both stave off disease and play an important role in boosting the immune system. Studies have shown that glutathione levels are often reduced in people with certain conditions related to the immune system.

For more than three decades, NAC has been used as a mucolytic (“Mucus dissolving”) agent to help break up the thick mucus often present in people suffering from chronic respiratory ailments. When administered intravenously, NAC has also proved invaluable in the treatment of acetaminophen overdose; it appears to protect the liver from this potentially toxic substance. Now widely available in supplement form, NAC is currently being recommended for preventing and treating a wide variety of ailments that may respond to its Antioxidant properties.

Health Benefits

Supplemental antioxidants–NAC is one of many– are believed to protect the body’s cells from altered oxygen molecules called Free radicals. Damage from free radicals is thought to be a signficant factor in such degenerative conditions as cancer and heart disease. Of course, factors other than oxidative damage, such as life style factors and genetic susceptibility, play strong roles in disease development as well. The hope is that by reducing susceptibility to free radical damage, a person may further lower susceptibility to a variety of chronic medical conditions. Incidentally, it is by means of its antioxidant actions that NAC helps the liver eliminate potentially dangerous environmental and biological toxins from the body.

Specifically, NAC may help to:

  • Reduce congestion related to sinusitis, bronchitis, asthma, and other respiratory diseases. Conventional physicians routinely use NAC to dilute thick mucus, making it much easier to cough up or drain from the nasal passages and other congested areas. It’s often used to ease congestion in people with pneumonia and other chronic respiratory diseases. It has even been shown to reduce mucus secretions in people who smoke or who are regularly exposed to secondhand smoke. Outcomes have not been as promising in the treatment of chronic obstructive pulmonary disease (COPD). Twenty-five patients administered NAC in addition to conventional medical treatments for COPD, did not show improved measure of breathing or earlier hospital release. Ask your doctor to assess whether adding NAC to your diet may be helpful in your condition.
  • Prevent damage from diabetic nephropathy. The end products of lipid oxidation cause nerve and kidney damage. Treatment with strong antioxidants such as NAC may help prevent or reduce the severity of diabetic nephropathy.
  • Treat HIV-infected individuals. Some studies have shown that NAC interferes with the replication of certain viruses, including the HIV (human immunodeficiency virus) responsible for causing AIDS. Just what this means for HIV-infected individuals remains unclear, however. Because NAC can boost glutathione production, it supports the proper functioning of immune-system components such as T cells, B cells, and phagocytes, all of which are important for maintaining the body’s defenses and potentially protecting against AIDs-related illnesses such as pneumonia.
  • Lessen flu symptoms. By thinning mucus and weakening the flu virus, supplemental NAC could potentially lessen the severity and duration of the flu. In a study of 262 elderly participants only 25% of the NAC treated group developed the flu symptoms compared to 79% of the group receiving Placebo.
  • Prevent heart disease. In some studies, NAC appears to significantly lower levels of Homocysteine and possibly lipoprotein(a), substances associated with an increased risk of heart disease. As an antioxidant, it also helps prevent the damaging oxidation–and thereby the precipitation–of LDL (“bad”) cholesterol from the material that lines blood vessels. More research in this area is needed, however.
  • Delay age-related cataracts and macular degeneration. Both of these conditions have been associated with damage from oxygen free radicals. By boosting antioxidant activity in the eye’s lens and macula, NAC may have a role to play in preventing cataracts (which cause the lens to become cloudy) and macular degeneration (which can result in blindness as this area of the retina deteriorates).
  • Counter environmental toxins. NAC-supported glutathione interacts with the dangerous byproducts of many toxic substances, promoting their excretion through the liver. These substances include carbon tetrachloride, chloroform, and carbon monoxide; alcohol; such heavy metals as mercury, chromium, and boron; and the microorganisms aflatoxin and Eschicheria coli.
  • Lessen the risk of cancer. By helping to rid the body of environmental toxins and by fighting free radicals, NAC, at least theoretically, may have a role to play in preventing cancer. NAC might also slow the growth of cancerous tissues in these ways. Clinical trials are underway to explore this possibility. Interestingly, one study did find that NAC reduced adverse reactions to chemotherapy.
  • Slow the progression of multiple sclerosis. One theory regarding the cause of this degenerative condition attributes it to free-radical damage caused by low levels of glutathione. If this is true, NAC’s antioxidant actions may be of help in protecting nerve cells from such damage. More research on NAC’s effect on this disease is clearly needed.
  • Affect the course of Parkinson’s disease. Parkinson’s disease is often marked by reduced quantities of glutathione in the brain. In theory, boosting glutathione with NAC supplements could slow loss of function in Parkinson’s. NAC’s antioxidant actions might also help by minimizing age-related deterioration of the nervous system.

Note: Antioxidants in general and NAC in particular have been considered useful for a number of other disorders. For information on these additional ailments, see our Dosage Recommendations Chart for NAC.


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Dosage Information

Special tips:

–Regular supplementation with NAC will increase the urinary excretion of copper, a Mineral. So if you’re using NAC for an extended period of time, it’s probably wise to add both copper (2 mg a day) and zinc (30 mg a day) to your treatment regimen.

–If you use NAC for more than a month, add a mixed amino acid complex to your treatment regimen to ensure that you are getting adequate, balanced amounts of all the Amino acids.

–NAC is also available as an intravenous solution and inhalant, but by prescription only. Follow doctor recommendations regarding dosage and administration of these forms.

  • For the majority of ailments mentioned: Take 500 mg three times a day.
  • For bronchitis: For acute bronchitis, take 500 mg three times a day between meals. For chronic bronchitis, take 250 mg three times a day between meals.
  • For sinusitis: Take 500 mg twice a day between meals.
  • For multiple sclerosis: Take 500 mg three times a day every other day between meals; alternate with 30 mg zinc and 2 mg copper.

Guidelines for Use

  • NAC is most effective when taken on an empty stomach.
  • If you’ve added a mixed amino acid complex to your NAC regimen, be sure to take it on an empty stomach as well, but at a different time of day than you take the NAC.

General Interaction

There are no known drug or nutrient interactions associated with NAC.

Possible Side Effects

  • NAC has no side effects as long as it is taken in the recommended dosage.
  • High doses of oral NAC may cause gastrointestinal problems, such as vomiting, or in rare cases a rash possibly accompanied by fever.


  • Scientists must still determine how much NAC and glutathione can be safely absorbed and processed by the body.
  • Evidence indicates that in some healthy individuals, high doses of NAC (2,800 mg a day) can act as a pro-oxidant rather than an antioxidant, actually lowering levels of glutathione rather than increasing them. For this reason, otherwise healthy individuals may want to avoid taking high doses of NAC until more information is available.
  • Because there are no adequate studies of NAC in pregnant women, it’s not recommended for women who are or may be pregnant.


Alcoholism – 600-1,000 mg twice a day

Asthma – 500 mg 3 times a day

Bronchitis – Acute: 600-750 mg 3 times a day until recovered.

Chronic: 600 mg twice a day

Cancer – 600 mg 3 times a day

Cancer Prevention – 600-1,000 mg once a day

Cataracts – 500 mg 3 times a day

Flu – 500 mg 3 times a day

Heart Disease Prevention – 500 mg 3 times a day

Macular Degeneration – 500 mg 3 times a day

Multiple Sclerosis – 600 mg 3 times a day

Psoriasis – 600 mg twice a day

Sinusitis – 600 mg 3 times a day between meals

For product recommendations and orders click here for the Natural Apothecary or call 773-296-6700, ext. 2001.

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33 comments on “NAC (N-acetylcysteine)
  1. Charles Williams says:

    Can someone tell me what I can take NAC with for a better digestion experience. I’ve only taken this once but it stirred up an already active acid redux condition. Would taking it on an empty stomach help this?

  2. Dr E says:

    I have the same problem with NAC myself. Taking it with a proton pump inhibitor like Nexium will help, or, if you’re using it as an antioxidant, try a new form of glutathione from Xymogen instead

  3. Charles Willliams says:

    Thanks for the info for it was most helpful.

  4. Charles Willliams says:

    thanks so much for the rresponse…most helpful.

  5. Jean says:

    Is this supplement helpful in treating bi-polar disorder?

  6. Elle says:

    How soon after I eat can I take an NAC? and by what time should I take the last NAC supplement? I also take milk thistle and caprlylic acid. Should I take them together or separately?

  7. Debbie says:

    I tried taking NAC, 600ml twice a day but had to stop as it was
    Making me dizzy and feeling terrible and couldnt sleep. I looked up possible side effects and it can cause these problems. Also Dr.
    Mercola suggests not to take NAC if you have dental amalgams, as since NAC is a natural detoxifier of mercury it could effect your Mercury detoxification.

  8. Majid says:

    I am taking 600 mg two times a day on empty stomach for vitiligo without copper and zine, though many research says zinc and copper are two super minerals that helps for vitiligo. Will it help me please.

  9. Dr E says:

    Hi Majid
    Natural treatments, including NAC, have been disappointing. You might get yourself tested for the MTHFR gene. If you are positive, some people are benefitting from methylated B-12, folate, combined with zinc and copper
    Good luck!

  10. laura says:


    I have been taking NAC for 2-3 weeks – 600mg daily. I have heart rhythm problems and “foggy head”. These pills seems to be making me more dizzy and VERY tired. Could this be the pills? Also, how long should a person take NAC for before people feel the correct way – should it be immediate or after a few months as i’m wondering whether to stop or push through. Thanks

  11. Dr E says:

    Hi Laura
    Both prescription medications and supplements can cause side effects in some people and with your NAC this definitely seems to be the case. I suggest simply stopping it and if all these symptoms go away in a couple of days, don’t bother with NAC anymore

  12. Ann says:

    Hi. My former doctor told me to take 600 mg NAC twice a day for obsessive-compulsive tendencies. Recently I accidentally ordered two bottles of 1000 mg NAC. I don’t want to waste them, but I am concerned about how safe it would be to take that much. Would it make sense to just take one capsule a day? Like in the morning so that its benefits would be seen during the day?

  13. Dr. R says:

    Ann. That would work or break the tablet in two.

  14. LK says:

    Take. NAC with Vitamin C. 600 mgs NAC 500mgs C

    People with MTHFR should NEVER take copper as a supplement without testing their copper/zinc/ceruloplasmin levels. It’s far more common to see a copper overload for people with MTHF mutations. Also Hydroxy B-12 is safe for all, Methyl B-12 can still cause issues.

  15. Debra Fleming says:

    Please tell be about NAC and Lyme disease.

  16. Dr. R says:

    Hi Debra
    NAC may help to inhibit biofilm formation by the bacteria. This would be one piece of a very complex treatment regime that would need to be individualized for a patient with Lyme and/or other co-infections.

  17. Dominique says:

    Hi, I undestand nac needs to be taken on an empty stomach but what about tea ? I drink Mate Tea first thing in the morning & wonder how long I have to wait for my nac dose. I only just started after a pleurisy which is almost gone. Thanks

  18. Dr. R says:

    Dominique. The tea shouldn’t be a problem.

  19. Chris says:

    How long should you take NAC? I have been through one bottle which I purchased for PCOS and I’m now not sure if I should buy another one. It is something your body needs a break from? Like three months on and then a month off?

  20. Dr. R says:

    Chris. If you’re improving, I’d suggest you continue for another month or so. Discussion with your primary care physician is always recommended as she/he is familiar with your overall health.

  21. LISA says:

    I know NAC detoxifies. How long should I wait to take other meds and supplements to insure that they are effective?

  22. Marcie says:

    I am taking NAC 600 mg twice a day for anxiety and OCD. I also take an iron supplement (325 mg twice a day) to keep my ferritin up. Are these ok to take together on an empty stomach with fruit juice?

  23. denise brickel says:

    DR R. I have 2 roots canal, can I take NAC safelely?

  24. Dr E says:

    There are several article in conventional psychiatry journals on the use of NAC for OCD and I find psychiatrists are actually recommending it.
    No problems using NAC with root canals

  25. Chloe says:

    I am taking antibiotics (Keflex) for my recurrent Urinary tract infection. I heard NAC disrupts bacterial biofilms and prevents chronic UTI. Can I take NAC and antibiotics together?

  26. Dr. R says:

    Chloe. Yes. There should be no interactions using NAC with Keflex.

  27. Antoinette says:

    Can NAC help with mixed connective tissue disease (autoimmune)?

  28. Dr. R says:

    Hi Antoinette. NAC as an adjunct therapy may be helpful especially with the inflammatory component of autoimmune disorders. In addition, lifestyle changes, including anti-inflammatory diet, possible gluten-free and dairy-free diets, moderate exercise, and stress reduction, will all be helpful. Remember, these are adjunctive therapies and not a replacement for treatment your doctor may recommend.

  29. Michelle says:


    I bought NAC after my psychiatrist recommended but it’s making me feel really tired after I take it 🙁 I really want to continue as its meant to help my condition a lot. I can already feel I am alot more focused, I have ADD. Is there any way to avoid this from happening? I am taking it at night only, but feel almost hung over the next day. I am taking powder too mixed with water, could this be affecting it? Thanks in advance!

  30. Anjana says:

    Can NAC supplementation cause fatigue?

  31. Dr. R says:

    Hi Anjana. NAC usually does not cause fatigue.


    I suffer from PRIMARY LATERAL SELOROSUS(Motor Neuron Disease)
    And I am going taking already daily twice
    L Serine 500 mg
    Coq10 400mg
    Maca Root
    Berberine 900mg
    Omega 3 fish oil 3600m
    Magnesium 833 mg(once daily)
    Since one week upto now everything normal.

    Is it safe to take NAC with this.
    Please suggest

  33. Dr E says:

    There would be no problem adding this

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