All perfect praise be to Allah, the Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
The basic principle is that it is permissible to use every useful thing unless there is a reason to forbid it, such as if it causes harm. This is evidenced by the well-established Shariah principle that states that, "All things are deemed lawful in principle (unless proven otherwise with religious evidence)." This rule is deduced from the hadeeth which was narrated on the authority of Salmaan Al-Faarisi who related that the Prophet, sallallaahu ‘alayhi wa sallam, said, "The lawful is what Allah deemed lawful in His Book, the unlawful is what Allah deemed unlawful in His Book; and what He remained silent about, then it is among that which He has pardoned." [At-Tirmithi and Ibn Maajah]
However, the reference in knowing what these drugs involve of benefits or harms are the specialists in this regard; the scholar cannot issue a fatwa declaring certain drugs harmful or beneficial unless he knows their true nature. Also, some drugs may be suitable for a person and unsuitable for another. Therefore, specialists must be consulted in this regard.
Allah knows best.