Use of cannabis to alleviate headache and migraine is relatively common, yet research on its effectiveness remains sparse. We sought to determine whether inhalation of cannabis decreases headache and migraine ratings as well as whether gender, type of cannabis (concentrate vs. flower), THC, CBD, or dose contribute to changes in these ratings. Finally, we explored evidence for tolerance to these effects. Archival data were obtained from Strainprint, a medical cannabis app that allows patients to track symptoms before and after using different strains and doses of cannabis. Latent change score models and multilevel models were used to analyze data from 12,293 sessions where cannabis was used to treat headache and 7,441 sessions where cannabis was used to treat migraine. There were significant reductions in headache and migraine ratings after cannabis use. Men reported larger reductions in headache than women and use of concentrates was associated with larger reductions in headache than flower. Further, there was evidence of tolerance to these effects. Perspective: Inhaled cannabis reduces self-reported headache and migraine severity by approximately 50%. However, its effectiveness appears to diminish across time and patients appear to use larger doses across time, suggesting tolerance to these effects may develop with continued use.