❌ I am taking a medicine for my stomach.
✅ I'm taking medicine for my stomach / I'm on stomach medication.
약을 말할 때는 보통 'medicine'이나 'medication'을 셀 수 없는 말로 쓰기 때문에 'a'를 붙이지 않아요.
잘못된 예: I have to skip coffee today because I'm taking a medicine for my stomach.
올바른 예: I have to skip coffee today because I'm taking medicine for my stomach.