3501 outpatients with fever due to respiratory disorders or eruptive diseases or to other causes were included in a post-marketing surveillance study aimed at extending knowledge of antipyretics and particularly of the paracetamol-sobrerol combination. The antipyretic activity of the drug under test was comparable to that of the reference molecules. Paracetamol-sobrerol combination exerted an extremely valid therapeutic action on cough and difficult expectoration, parameters which usually are associated with the phlogosis and congestion typical for airway infections. As already observed in literature, patients receiving salicylates complained of side effects while patients treated with pyrazolics complained of side effects involving nervous system and cardiovascular apparatus. Side effect incidence in patients treated with the paracetamol-sobrerol combination (3.7%) was significantly lower than that observed in subjects treated with paracetamol (6.1% - P less than 0.01), salicylics (25.1% - P less than 0.001), pyrazolics (12.6% - P less than 0.001), propionics (20.3%, P less than 0.001) or other antipyretics (17.9% - P less than 0.001). These findings demonstrate that the paracetamol-sobrerol combination is a valid therapeutic tool and is particularly suitable in febrile airway pathology. In addition, the low incidence of side effects due to the lower doses of paracetamol, makes this product well tolerated also by at risk subjects such as children and old patients.