The purpose of the study is to explore the effects of progesterone on cannabis withdrawal in women who regularly smoke marijuana. Participants will be asked to abstain from marijuana use for 5 days after the onset of menses. They will receive 8 doses of either progesterone or placebo during this time. On Days 1 and 5 they will come to the clinic to complete study assessments and provide urine, saliva and blood samples.On Days 2-4 assessments will be completed via text messages, Redcap surveys and video calls. Participants will be monitored for adverse events and cannabis withdrawal on each study day.