The purpose of this study is to determine whether or not inhaled marijuana displays any pain-relieving properties on experimentally-induced pain.

It is important to evaluate the effects of the cannabinoids on facilitated pain as conditions of hyperalgesia more closely approximates the clinical situation. There are limited clinical studies on the effect of the cannabinoids on facilitated pain states. Noyes et al evaluated the analgesic effects of Delta-9-THC in 34 cancer patients with pain. They concluded that 20mg of oral Delta-9-THC was similar to 120mg of codeine (Noyes et al, 1975). Jain et al concluded that 1.5-3mg of intramuscular Levonantradol resulted in significant pain relief as compared to placebo in 56 patients with acute postoperative pain (Jain et al, 1981).

Comparison(s): Three different doses of smoked cannabis will be compared to placebo for the reduction of experimentally induced pain.

Inclusion Criteria:

• Age 18-90
• Male or Female
• Subject smoked cannabis within the last six months

Exclusion Criteria:

• Active opportunistic infections or opportunistic malignancies requiring acute treatment
• Active substance abuse (alcohol or injection drug)
• Pulmonary complications (e.g., tuberculosis, asthma)
• Current use of cannabis (e.g., within 30 days of randomization)
• Pregnancy as ascertained by a self-report and a mandatory commercial pregnancy test before any cannabis or placebo consumption condition
• Personal or familial history of psychiatric disorder