Key takeaways
Hyoscyamine (Levsin, Hyosyne, Symax, Oscimin, NuLev) and Donnatal (phenobarbital / hyoscyamine / atropine / scopolamine) are both used to treat stomach problems like irritable bowel syndrome (IBS). They both contain hyoscyamine, an anticholinergic medication that helps relax stomach muscles and slow gut movement. However, they differ in several ways. Hyoscyamine is a single anticholinergic medication, while Donnatal is a combination of four medications, including a barbiturate (phenobarbital) and three anticholinergics (hyoscyamine, atropine, and scopolamine). Hyoscyamine is available in various forms, such as tablets and liquid, and is typically taken every 4 hours and may be used as needed. Donnatal is available as tablets and elixir and is taken 3 to 4 times a day. Hyoscyamine is available as a lower-cost generic. Donnatal is also available as a generic, but is technically not FDA-approved (rated by the FDA to be "possibly" effective). Common side effects of both medications include dry mouth and dizziness, but Donnatal has a risk of misuse and dependence due to phenobarbital, and is a controlled substance in some states.
