CBD vs. THC: What's the Difference? Steven Gans, MD is board-certified in psychiatry and is an active supervisor, teacher, and mentor at Massachusetts General Hospital. What is the most important information I should know about THC and CBD? You should always talk to your doctor first before you try any products containing THC and CBD and check the legal status of such products in your state. Both CBD and THC hold promise for alleviating symptoms and even treating some medical and mental health conditions, but research in this area is still relatively new, and further investigation is needed. While CBD is not addictive, THC is