On a website of the US National Institutes of Health many ongoing clinical studies are listed. Please note that this list is not complete.

Here are some of the many current clinical studies.

THC / Dronabinol / Marinol
Efficacy Trial of Oral Tetrahydrocannabinol in Patients With Fibromyalgia at Hadassah Medical Organization, Jerusalem, Israel.
For more studies please click here.

Nabilone / Cesamet
Efficacy and Safety Evaluation of Nabilone as Adjunctive Therapy to Gabapentin for the Management of Neuropathic Pain in Multiple Sclerosis at University of Manitoba, Winnipeg, Canada.
For more studies please click here.

Nabiximols / Sativex
A Study of Sativex® for Relieving Persistent Pain in Patients With Advanced Cancer in the United States, the UK and Germany.
For more studies please click here.

Cannabidiol (CBD)
Cannabidiol for Inflammatory Bowel Disease at Meir Medical Center, Kefar Saba, Israel.
For more studies please click here.

Smoked / Inhaled Cannabis
Comparing the Effects of Smoked and Oral Marijuana in Individuals With HIV/AIDS at New York State Psychiatric Institute, USA.
Effects of Vaporized Marijuana on Neuropathic Pain at CTSC Clinical Research Center, Sacramento, United States.
For more studies please click here.