N-Acetyl Cysteine (NAC)
What is it? Overview Usage Side Effects and Warnings

What is N-Acetyl Cysteine (NAC)?

N-acetyl cysteine (NAC) is a specially modified form of the dietary amino acid cysteine. When taken orally, NAC is thought to help the body make the important antioxidant enzyme glutathione. It has shown promise for a number of conditions, especially chronic bronchitis.

Significant but not entirely consistent evidence suggests that regular use of NAC is helpful for individuals with chronic bronchitis (a condition commonly associated with smoking and emphysema) in reducing frequency of acute flare-ups of the condition. 1 Regular use of NAC may help prevent influenza , possibly by stimulating immunity. 2 One substantial study found evidence that NAC may augment the effectiveness of clomiphene , a drug used for female infertility , in women with polycystic ovary syndrome . 3 Another study found NAC far less effective for this purpose than the drug metformin; however, it still could have provided some benefit.

Mixed evidence suggests that NAC may also enhance the effectiveness of the drug nitroglycerin , 4 5 6 7 8 used for...

Safety Issues

NAC appears to be a very safe supplement when taken alone, although one study in rats suggests that 60 to 100 times the normal dose can cause liver injury. 9 As mentioned above, the combination of nitroglycerin and NAC can cause severe headaches. Safety in young children, women who are pregnant or nursing, and individuals with severe liver or kidney disease has not been established.

Interactions You Should Know About

If you are taking nitroglycerin, NAC may cause severe headaches.