Marijuana can lead to temporary cerebrovascular ischemia, but this is not directly affected by most pain medications. Pain medications for neuropathic and cancer pain such as Sativex are derived from marijuana, the National Pain Report advises. As such, these drugs may have additive effects with marijuana.
The microvascular ischemia caused by marijuana is generally short-lived, according to the American Journal of Neuroradiology. There are some reports of marijuana use causing ischemic stroke, but these have not been verified. In both cases, pain medications, even those derived from marijuana, do not cross-react with marijuana to trigger or worsen symptoms if the drug is not taken concurrently with marijuana.