GlyNAC (glycine and NAC)

What it is

NAC is used as a drug for acetaminophen overdose and to help break up mucus. A review of studies found NAC is a good source of sulfhydryl groups, a type of sulfur-containing chemical group.

Sources: Memorial Sloan Kettering (About Herbs): N-Acetylcysteine ↗ · PubMed abstract: Clinical applications of N-acetylcysteine - PubMed ↗

How it's thought to work

• NAC is a building block the body uses to make glutathione, a natural antioxidant.
• As an antioxidant, NAC is thought to reduce DNA damage.
• NAC is thought to protect the liver partly by refilling glutathione and through cytokine-related actions.

Source: Memorial Sloan Kettering (About Herbs): N-Acetylcysteine ↗

What the research has found so far

• NAC has not been proven to treat cancer.
• For chronic lung disease, results are mixed.
• For depression added to other treatment, results are mixed and more studies are needed.
• Small studies suggest NAC might prevent some pre-cancerous damage, but there is no proof it prevents cancer.

Source: Memorial Sloan Kettering (About Herbs): N-Acetylcysteine ↗

On GlyNAC and aging, PubMed lists 1 trial in people, 0 studies that watched people over time, 5 animal and lab studies. See the counts and searches

Side effects and risks

• The pages list stomach upset, diarrhea, nausea, vomiting and similar problems as the common side effects of NAC.
• Common side effects include stomach upset, diarrhea, nausea, vomiting, tiredness, eye irritation and skin rash.
• Less common effects include low blood pressure, a severe allergic reaction, asthma attacks and headache.
• Light sensitivity occurred in lung scarring patients taking NAC with the drug pirfenidone.
• One study noted an unpleasant odor that was partly masked by diluting the product.

Source: Memorial Sloan Kettering (About Herbs): N-Acetylcysteine ↗

Who should be careful, and drug interactions

• It is controversial whether antioxidants like NAC lessen or cancel the effects of cancer treatment.
• In an animal model, NAC appeared to speed up lung cancer growth.
• In animal models, NAC may increase the effects of two antidepressants, though the human relevance is not known.

Source: Memorial Sloan Kettering (About Herbs): N-Acetylcysteine ↗

Approval and legal status

NAC is approved by the FDA for treating potentially liver-harming doses of acetaminophen. NAC is also approved for thick, sticky mucus conditions such as pneumonia, bronchitis and cystic fibrosis.

Source: PubMed abstract: N-Acetylcysteine - PubMed ↗

Roughly what it costs

The 6 products we list that contain GlyNAC cost from $19.95 to $63, as read from the makers' pages. See the products

Questions to ask your doctor

• Is GlyNAC a sensible option for me, given my health and the medicines I take?
• Could GlyNAC interact with any medicine or supplement I already take?
• What side effects should I watch for, and when should I stop or call you?
• Supplements aren't checked by the FDA before sale. Is there a brand or a third-party test seal you would trust?
• How would we tell whether it is helping, and when should we review it?