A method and a device for monitoring infusions at a patient is provided with a dispensing unit (2) for the infusion solution, a labeling substance (3) supplied additionally into the infusion solution by means of a dispensing unit or a drug and with a sensor (5) responding specifically to a physical or chemical property of the labeling substance (3) or of the drug at the body of the patient (1), so that depending on the signal of the sensor (5), an alarm is triggered via an evaluating unit (6) when the signal of the sensor (5) does not detect the presence and/or the quantity of the labeling substance (3) or of the drug, especially after comparison with set values.