The combination of drugs may be a result of a necessary therapeutic strategy against a single disease or a fortuitous treatment of two or more health disorders. In either case, a consequence of such approach is the increased risk of drug interactions and subsequent adverse effects. For the elderly, the probability of these events is significantly increased compared to other age groups, not only because of combining medications but also agerelated pharmacokinetic (absorption, distribution, biotransformation and excretion processes) alteration. Since the growth rate of the elderly population worldwide is rapidly increasing, clinicians should be extremely cautious of the drugs prescribed to older patients in order to minimize drug interactions and therapeutic failure.