The major constituents in andrographis are diterpene lactones known as andrographolides. These bitter constituents are believed to have immune-stimulating, anti-inflammatory, fertility-decreasing, liver-protective, and bile secretion-stimulating actions.³ Though some older studies suggested andrographis was antibacterial, modern research has been unable to confirm this finding.⁴

A few double-blind clinical trials have found that andrographis can help reduce symptom severity in people with common colds.^{5, 6, 7, 8, 9} Though the earliest clinical trial among these showed modest benefits, later studies have tended to be more supportive. Standardised andrographis extract combined with eleuthero (Siberian ginseng), known as Kan jang, has also been shown in a double-blind clinical trial to reduce symptoms of the common cold.¹⁰

A preliminary uncontrolled study using isolated andrographolide found that while it tended to decrease viral load and increase CD4 lymphocyte levels in people with HIV infection, at the amount used, the preparation led to side effects, including headache, fatigue, a bitter/metallic taste in the mouth, and elevated liver enzymes (which returned to normal after the medication was stopped).¹¹ It is unknown whether the andrographolides used in this study directly killed HIV or had an immune-strengthening effect.

Andrographis has proven helpful in combination with antibiotics for people with dysentery, a severe form of diarrhoea.¹² It has also shown preliminary benefit for people with chronic viral hepatitis.¹³