Morphine produces a physical dependence that develops quickly and increases in intensity with increased dosage. When the body's supply of morphine is withheld, withdrawal symptoms occur within a few hours, reaching a peak in intensity within 24 to 48 hours, and then begin to subside. Moreover, the drug produces a rapid tolerance level, a desensitization which requires increasing dosages to achieve the desired effect. Increased dosages produce a greater physical and psychological dependence, resulting in addiction.