deteriorate, lapse, relapse, decline, set someone back, revert, degenerate, worsen, regress, slide back, fall (into decline), take a turn for the worse, suffer a relapse, get ill again, slip back, backslide, get worse, act up, test (positive)

cramp, chafe, scratch, curl up, twitch, sweat, perspire, flush, bleed, pant, black out, burn, narrow, drain, put up with, sting, flag, huff, prickle, linger, gasp, twinge, vomit, barf, cough, itch, ache, curdle, dry out, get the runs, pulsate, sneeze, wheeze, faint, turn over (stomach), come down with, catch (a cold), run (nose), break out in, buckle (at the knees), swoon

spread, destroy, compromise, trigger, transmit, cover, riddle, weaken, jeopardize, impair, obstruct, devastate, destabilize, eat away at, debilitate, infest, reduce to, putrefy, aggravate, exacerbate, tax (an organ), wither (a limb), attack (the immune system), infect, afflict

crack, droop, shrivel, break down, perish, die, age, shrink, bury, wane, weaken, sink, vanish, disappear, decay, disintegrate, deteriorate, succumb, fail, relapse, decline, expire, flag, mutate, wither (away), dissolve, degenerate, waste away, grow old, disfigure, rot, fade away, go limp, lose color, ossify, calcify, give up the ghost, pass away/on, buy the farm, cash in one's chips, kick the bucket, meet one's maker, lay down one's life, bite the big one, croak, atrophy, cremate