Isoniazid is effective in helping to prevent tuberculosis in people not infected with HIV

Tuberculosis (TB) is a serious bacterial infection and it is estimated that about a third of the world's population is infected with TB. There are a number of types, such as pulmonary TB (bacteria residing in a person's lungs) and spinal TB (in the spine). Some bacteria can be drug resistant and some people may have the infection alongside another medical condition. People suffer from severe cough, weakness and sweats, and some people still die from TB even though effective drug treatment has been around for many years. The incidence of TB has reduced in areas where the drugs are readily available. Preventing people from contracting TB in high-risk areas is a goal worth pursuing. The review of trials using isoniazid for a six- to 12-month period in people without HIV infection (HIV infected people were studied in another review) identified 11 trials involving over 90,000 people. Isoniazid was effective in preventing TB in 60% of people, although some did develop hepatitis. The findings showed that one person can be saved from getting TB when 35 people take isoniazid for six months, and one in every 200 treated will get hepatitis. The balance of benefits and harms need to be carefully considered for each setting where intervention is being considered.