4-Aminosalicylic acid is primarily used in the treatment of tuberculosis, particularly in cases where the bacteria have developed resistance to first-line drugs like isoniazid and rifampin. It works by inhibiting the synthesis of folic acid in Mycobacterium tuberculosis, thereby preventing the bacteria from growing and multiplying.

In addition to its antitubercular properties, it has been explored for its potential anti-inflammatory effects, making it a candidate for treating inflammatory bowel diseases such as Crohn's disease and ulcerative colitis. However, its use in these conditions is less common compared to other medications.

The compound is also studied for its antioxidant properties, which may contribute to its therapeutic effects. It is sometimes used in combination with other drugs to enhance efficacy and reduce the risk of resistance development.

Due to its specific mechanism of action, it is often reserved for multidrug-resistant tuberculosis cases or as part of a tailored treatment regimen under medical supervision.