Smartphones, mobile applications ('apps'), social media, analytics, and the cloud are profoundly changing the practice of medicine and the way health decisions are made. With the constant progress of technology, the measurement of vital signals becomes easier, cheaper, and practically a standard approach in clinical practice. The interest in measuring vital signals goes beyond medical professionals to the general public, patients, informal caregivers, and healthy individuals, who frequently lack any formal medical training. On smartphone platforms such as iOS and Android, a proliferation of health or medical 'apps' acquire and analyse a variety of vital signs through embedded sensors, interconnected devices or peripherals utilising on occasion analytics and social media. Smartphone vendors compete with traditional medical device manufacturers in the grey area between health care, wellness, and fitness, as US and EU regulatory bodies are setting and revising rules for these new technologies. On the other hand, in the absence of robust validation results, clinicians are hesitant to trust measurements by apps or recommend specific apps to their patients, partly also due to lack of a cost reimbursement policy. This review focuses on the acquisition and analysis on smartphones of three important vital signs in the cardiovascular and respiratory field as well as in rehabilitation i.e. heart or pulse rate, blood pressure, and blood oxygenation. The potential, pitfalls, and perspectives on mobile devices and smartphone apps for health management by patients and healthy individuals are discussed.