The discovery that the capsule and powder forms of the popular Po Chai Pills contained harmful chemicals has led critics to question the monitoring system for Chinese medicines. They say the government must step up supervision to better protect consumers.
In late March, the Department of Health ordered a recall of the medicine and warned that the public - especially children and the elderly - should stop taking them after authorities in Singapore found they contained two chemicals that have serious side-effects.
The pills have been popular for more than 100 years and are used to relieve gastric problems and, even by some, to prevent hangovers.
Initial investigations suggested the raw materials for the capsule and powder formulas had been contaminated with phenolphthalein and sibutramine before production.
Phenolphthalein is used for treating constipation but was banned in Hong Kong in 2001 because of its cancer-causing properties.
Sibutramine is a Western appetite suppressant. Its side-effects include heightened blood pressure and heart rate, psychosis and possibly seizures.