<p>Sibutramine should not be given concurrently with, or within at least two weeks of stopping an MAOI; at least two weeks should elapse between discontinuation of Sibutramine and starting therapy with an MAOI. There is a risk of the serotonin syndrome developing if Sibutramine is administered together with other serotonergic drug such as selective serotonin reuptake inhibitors (SSRIs), sumatriptan, lithium, pethidine, fentanyl, dextromethorphan and pentazocine. Sibutramine should not be used with other drugs that may increase heart rate or blood pressure such as ephedrine, phenylpropanolamine, and pseudoephedrine (which may be ingredients of some cough and cold remedies). Alcohol should be avoided. Inhibitors of the cytochrome P450 isoenzyme CYP3A4, such as ketoconazole and erythromycin, may increase plasma concentrations of Sibutramine.</p>