Hyoscyamine Pharmacology

Hyoscyamine is an anticholinergic medication that is primarily used for GI problems like spasms and pain associated with IBS. Because of the highly anticholinergic nature of hyoscyamine, it can cause dry eyes, dry mouth, urinary retention, and constipation. Be aware of the risk for the prescribing cascade with hyoscyamine. Saliva substitutes for dry mouth, artificial tears for dry eyes, etc. Sedation is a concern with hyoscyamine and this can be exacerbated by drugs like benzodiazepines, opioids, and older antihistamines.