Predisposing factors of urinary retention eg, spinal cord lesion, prostatic hyperplasia; patients w/ epilepsy or at risk of convulsion. Allow 3-day wash-out period before performing allergy skin tests. Concurrent intake of alcohol. May affect ability to drive & use machines. Renal & hepatic impairment. Lactation. Not recommended in infants & toddlers <2 yr. Elderly.