1. 
[syn: distressing, distressful, disturbing, perturbing, troubling, worrisome, worrying]
WordNet (r) 3.0 (2006):
perturbing
    adj 1: causing distress or worry or anxiety; "distressing (or
           disturbing) news"; "lived in heroic if something
           distressful isolation"; "a disturbing amount of crime";
           "a revelation that was most perturbing"; "a new and
           troubling thought"; "in a particularly worrisome
           predicament"; "a worrying situation"; "a worrying time"
           [syn: distressing, distressful, disturbing,
           perturbing, troubling, worrisome, worrying]
Moby Thesaurus II by Grady Ward, 1.0:
63 Moby Thesaurus words for "perturbing":
   agitating, baffling, bewildering, bothering, breathtaking, charged,
   cliff-hanging, confounding, confusing, discomposing, disconcerting,
   dismaying, disquieting, distracting, disturbing, electric,
   embarrassing, enigmatic, exciting, exhilarating, galvanic, heady,
   heart-expanding, heart-stirring, heart-swelling, heart-thrilling,
   impressive, inflammatory, intoxicating, intricate, jarring,
   jolting, maddening, mind-blowing, moving, mysterious, mystifying,
   overcoming, overmastering, overpowering, overwhelming, perplexing,
   piquant, problematic, provocative, provoking, puzzling, ravishing,
   soul-stirring, spirit-stirring, stimulating, stimulative, stirring,
   striking, suspenseful, suspensive, tantalizing, telling, thrilling,
   thrilly, troubling, unsettling, upsetting