N-Acetylcystein

N-acetylcysteine (NAC) may reduce flu symptoms and ease mucus congestion; evidence for preventing infection is mixed. 1 2

• Influenza study: One study found clinically apparent flu in 25% of participants taking NAC versus 79% taking placebo. NAC may increase glutathione, an antioxidant involved in the body’s response to cellular stress. 3 4
• Mucus: NAC is a mucolytic—it loosens mucus, which can ease buildup and congestion. 5
• Doses discussed: For prevention, 1,200 mg daily split into two 600 mg doses; for an established cold, 900 mg three times daily. 6
• Availability: NAC was described as available over the counter in the United States at the time of recording, though its regulatory status had been contested. 7