I am doing some research about marijuana and I have questions about how Islam views it.

1-Why should marijuana remain illegal in Islam?

2-What are the evidences in Islam to show that marijuana is haram?

3-Is there an ayah (Quranic verse) or hadith to show that marijuana is not allowed in Islam?

4-What are the side effects that marijuana causes, according to Islam?

5-What about using marijuana as a medication to remove pain?

In the name of Allah, the Most Merciful, the Grantor of Mercy

All praise belongs to Allah, and may prayers and peace be upon Allah’s final Messenger.

Marijuana clouds one’s consciousness and impairs the judgment. Intoxicants that do this are forbidden by consensus in Islam.

In Islam, necessity mandates exemptions, and the use of a certain substance is judged on the basis of the balance between the harm and benefit.

For individuals with severe chronic pain, the use of legally prescribed opiates and the like would be permissible. [However, opiates can be highly addictive and have been shown to be a gateway to illegal drugs, so it is advised to ask your healthcare provider to recommend some pain relief options that are safer and not addictive.]

Allah knows best. 

Related fatawa: 77834, 78651, 83807, 85723, 85873