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N-Acetyl Cysteine (NAC)

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N-acetyl cysteine (NAC) is used by the body to build antioxidants. Antioxidants are vitamins, minerals, and other nutrients that protect and repair cells from damage.

You can get NAC as a supplement or a prescription drug.

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Why do people take NAC?

As a prescription drug, doctors use NAC to treat acetaminophen overdose. It may also help break up mucus in people with some lung diseases, like chronic bronchitis.

As a supplement, some people use NAC to try to protect the liver. There's evidence it can help prevent liver damage caused by some cancer drugs.

Some animal studies have shown that NAC may help protect against some cancers. However, we don't know if it would have anti-cancer benefits in people.

There's mixed evidence about whether NAC helps with other conditions, like infertility, the flu, cystic fibrosis, liver disease, angina, HIV, and some eye conditions. More research is needed.

Optimal doses of NAC as a supplement have not been set for any condition. Quality and active ingredients in supplements may vary widely from maker to maker. This makes it very hard to set a standard dose.

There are standard doses for prescription uses of NAC. These depend on the condition that is being treated. Ask your doctor for advice.

Can you get NAC naturally from foods?

NAC is not in foods.

What are the risks?

Tell your doctor about any supplements you're taking, even if they're natural. That way, your doctor can check on any potential side effects or interactions with medications.

Side effects. NAC may cause:

  • Upset stomach
  • Diarrhea
  • Fatigue
  • Skin rash

Risks. Extremely high doses -- 60 to 100 times the normal amount -- have caused liver damage in animals. NAC may not be safe for people with asthma or with severe liver or kidney disease.

If you're pregnant or breastfeeding, you must check with a doctor before using NAC supplements.

Interactions. If you take any medicines regularly, talk to your doctor before you start using NAC supplements. They could interact with nitroglycerin or other medications.

Supplements are not regulated by the FDA.

WebMD Medical Reference

Reviewed by Melinda Ratini, DO, MS on January 11, 2013

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