migraine
"This medicine has changed my life: it is a 100% surefire defense against debilitating migraines.  I can actually feel it pushing the headache out of my head. One word of caution, however: in the rare instance I feel a headache coming on and don't have my meds with me (or, more likely, am out of them since the insurance allows only a 9-pill script), the headache that I do get is OFF THE CHARTS.  It's almost like the migraine monster knows I have no defense."