What does it mean to be lucky to take medicine?

There seems to be only one place where this word is used.

Li Mingtang is so clever that he can always see through it a little bit, which is not hard to understand the implication of the emperor. It's a pity that he has been released on parole for medical treatment these days, and his mind is only wandering about Shao Hua's double suicide, his mother's illness and how he resigned from the disaster. He never dreamed that Empress Zhaoyang of the Deep Palace would collude with the Empress Dowager and design to earn him. However, Cheng Zongsu is always so attentive to him. For a time, he neglected to see the change of the emperor's anxious expression and tone, and casually replied: "I took a leave of absence for many days because of my dog's illness, which delayed many government affairs. Fortunately, there is no medicine now, how dare you steal to extend the holiday? "

Meaning:

Fortunately, fortunately, I finally don't have to take medicine now.