As the first line strategy, the troops were given synthetic drugs. Drug combinations using pyrimethamine and dapsone, pyrimethamine and sulfadoxine, and sulfadoxine and piperaquine phosphate were tested in the battlefield. Because these drugs had serious adverse effects, the primary focus was to examine traditional Chinese medicines and look for new compounds. The first drug of interest was chángshān (), an extract from the roots of Dichroa febrifuga depicted in the Shennong Ben Cao Jing. Another early candidate was huanghuahao (sweet wormwood or Artemisia annua). These two plants became a huge success in modern pharmacology.