Smartphones have become an indispensable part of daily life, and their increasing use has raised concerns about various health effects, including musculoskeletal symptoms. Repetitive movements of the thumb and hand muscles can lead to issues such as tendinosis, myofascial pain syndrome, and a decrease in pinch strength. Studies have shown that musculoskeletal symptoms related to smartphone use are common among young adults and university students. Additionally, an increase in device size may place greater strain on the wrist and finger muscles. Repetitive movements can cause stiffness changes in the thumb muscles, and the relationship between these changes and pinch strength is considered an important research topic. In this study, we aimed to investigate the effects of smartphone addiction on pinch strength, muscle stiffness, hand/wrist pain, and function in young adults.