Risk of non-serotoninergic syndrome w/ MAOIs. Increased sedative effect w/ alcohol. Increased risk of convulsions w/ medicinal products reducing seizure threshold eg, bupropion, serotonin reuptake inhibitor antidepressants, TCAs & neuroleptics. Decreased analgesic effect by competitive blocking effect at the receptors & risk of occurrence of w/drawal syndrome w/ opioid agonists-antagonists (buprenorphine, nalbuphine, pentazocine). Increased risk of resp depression w/ other opioid derivatives (including antitussive drugs & substitutive treatments), benzodiazepines & barbiturates. Increased central depression w/ other central nervous system depressants eg, other opioid derivatives (including antitussive drugs & substitutive treatments), barbiturates, benzodiazepines, other anxiolytics, hypnotics, sedative antidepressants & antihistamines, neuroleptics, centrally-acting antihypertensives, thalidomide & baclofen. Increased INR w/ warfarin-like compds. Tramadol: Decreased plasma conc w/ carbamazepine & other enzyme inducers. Serotonin syndrome w/ other serotoninergic medicines eg, SSRIs & triptans. Inhibit metabolism w/ other drugs known to inhibit CYP3A4 eg, ketoconazole & erythromycin. Pre- or postop application of antiemetic 5-HT3 antagonist ondansetron increased requirement of tramadol in patients w/ postop pain. Paracetamol: Absorption of paracetamol increased by metoclopramide or domperidone & reduced by cholestyramine.