Take your pick:
harmful
adj
damaging, detrimental, bad, pernicious, unhealthy, unwholesome, injurious, wounding, dangerous, hazardous, poisonous, toxic, destructive, noxious, deleterious
painful
adj
1 SORE, tender, hurting, irritating, inflamed, aching, throbbing, smarting, stabbing, agonizing, excruciating
2 a painful experience unpleasant, disagreeable, distressing, upsetting, saddening, wretched, miserable, agonizing, disturbing, harrowing, traumatic, disquieting
3 EMBARRASSING, awkward, uncomfortable, disconcerting, distressing, upsetting, sensitive, mortifying, humiliating, shameful, shaming, discomfiting, touchy
4 HARD, difficult, tough, trying, exacting, laborious, tedious, arduous, rigorous, strenuous