In this paper, through a thematic literature review of recent studies, our objective was to explore the impact of loneliness and its effects on health. We emphasize the human need for a sense of belonging and societal inclusion. We further discuss the link of loneliness to physiological alterations, to the development and exacerbation of mental health conditions, the influence it has on cognitive processes, and the role it plays in contributing to maladaptive coping strategies. Contrary to the feelings of loneliness, solitude and its benefits for self-reflection and personal growth are explored. The prevalence of loneliness and its cultural similarities and differences are discussed at a global level. Moreover, this review explores the intricate relationship between loneliness and various health outcomes, including chronic illness and mortality risks. It further emphasizes the importance of acknowledging loneliness as a public health concern and the need for interventions at the individual and societal level to mitigate its adverse effects.