Write SQL query to solve given problem: Why did Elly Koss need to take Acetaminophen?. Keep the solution inside sql tag ```sql [SQL-Query] ```
SELECT T2.REASONDESCRIPTION FROM patients AS T1 INNER JOIN medications AS T2 ON T1.patient = T2.PATIENT WHERE T1.first = 'Elly' AND T1.last = 'Koss' AND T2.description LIKE 'Acetaminophen%'