Tramadol HCl is well tolerated. Adverse effects possibly related to tramadol are mild, transient and rare. These are anorexia, flatulence, vasodilation, orthostatic hypotension, syncope, tachycardia, palpitations, urinary retention, visual disturbances, anxiety, confusion, euphoria, nervousness, co-ordination disturbances, allergic reactions, skin rashes, urticaria and weight loss.