deleterious (adj.)

• baleful
• baneful
• corrosive
• corrupting
• corruptive
• counterproductive
• damaging
• deadly
• destroying
• destructive
• detrimental
• disadvantageous
• distressing
• harmful
• hurtful
• injurious
• lethal
• malefic
• malevolent
• malign
• malignant
• mischievous
• noisome
• noxious
• ominous
• pernicious
• poisonous
• prejudicial
• ruinous
• toxic
• unfavorable
• unprofitable
• unrewarding
• useless
• venomous
• vicious
• virulent
• worthless