Patients w/ predisposing factors of urinary retention eg, spinal cord lesion, prostatic hyperplasia; epilepsy, at risk of convulsions. Consider 3-day wash-out period before performing allergy skin tests. W/drawal syndrome. Concurrent use of alcohol. May cause allergic-type reactions due to Na metabisulfite. Not to be taken by patients w/ galactose intolerance, Lapp lactase deficiency or glucose-galactose malabsorption. Pregnancy & lactation. Not recommended in childn <6 yr.