Alcohol and substance use disorders (ASUD) are chronic, relapsing psychiatric conditions with significant individual and public health implications. While their neuropsychiatric effects are well documented, their dermatological manifestations often remain under-recognized in clinical practice, leading to delays in diagnosis and treatment. This narrative review systematically explores skin findings associated with the use of alcohol, cannabis, hallucinogens, inhalants, opioids, stimulants, and tobacco, based on recent literature. Alcohol is frequently linked with telangiectasias, seborrheic dermatitis, pruritus, and rosacea-like eruptions. Opioid use often results in pruritus, ulcerations, and scarring at injection sites. Stimulants such as cocaine and amphetamines are associated with vasculitic rashes, formication-induced excoriations, and ulcerative dermatoses. Cannabis, hallucinogens, and inhalants may cause contact dermatitis, pigmentary changes, and perioral lesions. Tobacco use, though legally sanctioned, significantly contributes to premature skin aging and exacerbation of chronic inflammatory dermatoses. Early recognition of these dermatologic signs may serve as clinical clues, aiding in the timely diagnosis of ASUD. Integrating dermatological evaluation into addiction treatment protocols can improve outcomes and reduce unnecessary investigations. This review emphasizes the importance of skin manifestations in ASUD and encourages greater clinical attention and multidisciplinary collaboration in addressing these often-overlooked indicators.