What are the side effects of traditional Korean medicine diet pills?

A younger sibling I know was worried because she couldn't lose weight after giving birth, so I prescribed her traditional Korean medicine diet pills, and she saw truly dramatic results.

The problem is that when you stop taking the medication, the symptoms come back too quickly.

Simply stopping medication, continuing exercise and diet control, but still experiencing a yo-yo effectㅠ

So, I take medicine again to really lose weightㅠ

Is it okay to keep doing that repeatedly, going back and forth? Are there any side effects? I'm worried.