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.