N-acetyl cysteine (NAC)

N-acetyl cysteine (NAC) is an antioxidant molecule that can absorb free radicals within the body. Free radicals are highly reactive, damaging chemicals that are produced in the body as a natural consequence of the use of nutrients by human cells.

High levels of free radicals can boost HIV replication and stimulate the death of T-cells. This may be one cause of the loss of CD4 T-cells in people with HIV.

NAC is believed to work by increasing the level of glutathione in cells, a molecule that helps cells produce energy and helps to protect them against damage from free radicals.1 2 It may also act as an immunomodulator, being necessary for T-cell activation.3

Although glutathione deficiency is common in patients with HIV, it remains unproven that artificially boosting glutathione levels will improve the prognosis of people with HIV. One double-blind placebo-controlled study of 45 asymptomatic patients in a four-month found no benefits of NAC in terms of CD4 cell count increases.4 In contrast, a study of patients taking antiretroviral therapy found that CD4 cell counts rose sooner if the patients were receiving 600mg NAC a day than if they were taking placebo.5

It has been suggested that NAC might reduce the allergic reactions experienced by some people taking cotrimoxazole (Septrin) as prophylaxis for Pneumocystis pneumonia (PCP), but two placebo-controlled studies have found no evidence of such an effect.6 7

NAC is used extensively in the United States by people with HIV who obtain it from buyers’ clubs or in ‘underground’ community trials. NAC is an approved treatment for bronchitis and paracetamol poisoning, but it cannot be prescribed on the National Health Service. NAC can also be purchased from many health food stores as a nutritional supplement.

When used for its approved indications, NAC is considered non-toxic. Inflammation of the mouth, nausea, vomiting and fever have been reported infrequently.


  1. Mihm S et al. Inhibition of HIV-1 replication and NF-kappa B activity by cysteine and cysteine derivatives. AIDS 5: 497-503, 1991
  2. Roederer M et al. Cytokine-stimulated human immunodeficiency virus replication is inhibited by N-acetyl-L-cysteine. Proc Natl Acad Sci U S A 87: 4884-4888, 1990
  3. Eylar E et al. N-acetylcysteine enhances T-cell functions and T-cell growth in culture. Int Immunol 5: 97-101, 1993
  4. Akerlund B et al. Effect of N-acetylcysteine (NAC) treatment on HIV-1 infection: a double-blind placebo-controlled trial. Eur J Clin Pharmacol 50: 457-461, 1996
  5. Spada C et al. The effect of N-acetylcysteine supplementation upon viral load, CD4, CD8, total lymphocyte count and hematocrit in individuals undergoing antiretroviral treatment. Clin Chem Lab Med 40: 452-455, 2002
  6. Akerlund B et al. N-acetylcysteine treatment and the risk of toxic reactions to trimethoprim-sulphamethoxazole in primary Pneumocystis carinii prophylaxis in HIV-infected patients. J Infect Dis 35: 143-147, 1997
  7. Walmsley SL et al. A randomized trial of N-acetylcysteine for prevention of trimethoprim-sulfamethoxazole hypersensitivity reactions in Pneumocystis carinii pneumonia prophylaxis (CTN 057). Canadian HIV Trials Network 057 Study Group. J Acquir Immune Defic Syndr Hum Retrovirol 19: 498-505, 1998

Community Consensus Statement on Access to HIV Treatment and its Use for Prevention

Together, we can make it happen

We can end HIV soon if people have equal access to HIV drugs as treatment and as PrEP, and have free choice over whether to take them.

Launched today, the Community Consensus Statement is a basic set of principles aimed at making sure that happens.

The Community Consensus Statement is a joint initiative of AVAC, EATG, MSMGF, GNP+, HIV i-Base, the International HIV/AIDS Alliance, ITPC and NAM/aidsmap

This content was checked for accuracy at the time it was written. It may have been superseded by more recent developments. NAM recommends checking whether this is the most current information when making decisions that may affect your health.

NAM’s information is intended to support, rather than replace, consultation with a healthcare professional. Talk to your doctor or another member of your healthcare team for advice tailored to your situation.