WordNet (r) 3.0 (2006):

laid low
    adj 1: put out of action (by illness) [syn: laid low(p),
           stricken]

Moby Thesaurus II by Grady Ward, 1.0:

69 Moby Thesaurus words for "laid low":
   ailing, ausgespielt, bad, below par, couchant, critically ill,
   crouched, debased, depressed, done, done up, down, effete, emptied,
   exhausted, faint, faintish, far-gone, fatigued, feeling awful,
   feeling faint, feeling something terrible, flat, frazzled, ill,
   in danger, indisposed, jaded, knee-high, knocked flat, low,
   low-built, low-hung, low-level, low-leveled, low-lying, low-set,
   low-statured, mortally ill, neap, not quite right, off-color,
   out of sorts, played out, pooped, prone, recumbent, rocky,
   run-down, runty, seedy, short, shotten, sick, sick unto death,
   sickish, spent, squat, squatty, stooped, stumpy, supine, taken ill,
   tired, under the weather, unelevated, unwell, used up, worn-out