harmful

Synonyms: adverse bad baleful baneful calamitous cataclysmic catastrophic consumptive corroding corrupting crippling damaging deleterious destructive detrimental dire disadvantageous disastrous evil harassing incendiary inimical internecine malefic malicious malignant menacing mischievous murderous nocuous noxious painful pernicious pestiferous pestilential risky ruinous sinful sinister subversive toxic undermining unhealthy unsafe unwholesome virulent

Antonyms: aiding assisting helpful nice unharmful