Rifampicin can be used alone in patients with latent tuberculosis infections to prevent or prolong the development of active disease because only small numbers of bacteria are present. A Cochrane review found no difference in efficacy between a 3- to 4-month regimen of rifampicin and a 6-month regimen of isoniazid for preventing active tuberculosis in patients not infected with HIV, and patients who received rifampicin had a lower rate of hepatotoxicity. However, the quality of the evidence was judged to be low. A shorter 2-month course of rifampicin and pyrazinamide had previously been recommended but is no longer recommended due to high rates of hepatotoxicity.