Pain is a widespread symptom in clinical practice. Older adults and chronically ill patients are particularly affected. In multimorbid geriatric patients, pharmacological pain treatment is an extension of a previously existing multimedication. Besides the efficacy of pain treatment, drug side effects and drug-drug interactions have to be taken into account to minimize the health risk for these patients. Apart from the number of prescriptions, the age-related pharmacokinetic and pharmacodynamic changes significantly increase the risk among older adults. The use of non-steroidal anti-inflammatory drugs (NSAID) is widespread but NSAIDs have the highest risk of adverse drug reactions and drug interactions. In particular, the gastrointestinal, cardiovascular, renal and coagulation systems are affected. Apart from the known toxic effect on the liver (in high doses), paracetamol (acetaminophen) has similar risks although to a lesser degree. According to current data, metamizol is actually better than its reputation suggests. The risk of potential drug interactions seems to be low. Apart from the risk of sedation in combination with other drugs, tramadol and other opioids can induce the serotonin syndrome. Among older adults, especially in the case of polypharmacy, an individualized approach should be considered instead of sticking to the pain management recommended by the World Health Organization (WHO) in order to minimize drug-drug interactions and adverse drug reactions.