Offensive cyber operations (OCOs) are increasingly employed by state and non-state actors to achieve strategic objectives in cyberspace. However, these operations often produce collateral effects and unintended repercussions that extend beyond their immediate targets. This systematic literature review analyzes academic and policy research to uncover the scope, nature, and consequences of such unintended outcomes. Key themes include civilian infrastructure disruption, geopolitical escalation, legal and ethical dilemmas, and blowback on originating systems. The review also highlights gaps in risk assessment methodologies and accountability frameworks within offensive cyber strategies. By synthesizing existing findings, the study aims to inform the development of more responsible and resilient cyber doctrines that minimize harm and ensure compliance with international norms.