Dì-yī gè liáochéng jiéshù hòu, tā de bìngqíng míngxiǎn hǎozhuǎn.
After the first course of treatment, his condition improved significantly.
Tips
usage
疗程 refers to a defined period of treatment, not a single visit. You 'complete a course' (完成一个疗程) or 'undergo a course' (做一个疗程). Common in both Western and traditional Chinese medicine contexts.