Described herein are methods for effectively and accurately measuring a patient response upon administration of one or more drugs to the patient. The methods are more sensitive than current methodologies. Also described herein are compositions comprising an analgesic and a sufficient amount of an antihistamine to enhance the analgesic properties of the analgesic. With respect to these compositions, the methods described herein are useful for evaluating qualities of pain, definite improvement, and one or more bodily functions of a subject afflicted with pain. The compositions described herein are useful in improving the quality of pain in a subject or a bodily function of a subject afflicted with pain or definite improvement of a subject afflicted with pain.