breakthrough pain

noun

: a transient, usually severe episode of pain occurring in individuals (such as cancer patients) being treated for chronic pain

Breakthrough pain describes a temporary pain that cancer patients may experience even if they are on other pain pills. The pain can flare from just a few seconds to several hours.

—Ken Alltucker, The Arizona Republic

In fact, only 42% of the physicians administered pain medication appropriately, and 80% did not prescribe any medication for breakthrough pain, which occurs frequently in cancer patients.

—Stuart L. Nightingale, The Journal of the American Medical Association