Finger sweat is explored here as a convenient and non-invasive method of monitoring therapeutic drugs and metabolites. Finger sweat samples were collected from multiple populations (including patients receiving treatment with antipsychotics and anti-tuberculosis medications, and negative controls) and analysed by liquid chromatography mass spectrometry. In patients receiving treatment with antipsychotics, the test (based on the detection of parent drug in one finger sweat sample) was 100% effective in monitoring adherence at typically prescribed dosages. However, one of the key challenges facing finger sweat analysis is the inability determine or control sample volume. Therefore, using the previously effective drug method, endogenous compounds (such as creatinine) simultaneously detected in samples from tuberculosis patients were evaluated as indicators of sample quality and potential normalisation candidates. Finally, in a controlled administration study, normalisation of parent drug to creatinine was able smooth the pharmacokinetic elimination profile of a key anti-tuberculosis drug (isoniazid) in finger sweat. Finger sweat shows promise as a quick and dignified method of monitoring patient adherence to prescribed medications.