They work by slowing the natural movements of the gut and by relaxing the muscles in the stomach and intestines. Belladonna alkaloids belong to a class of drugs known as anticholinergics/antispasmodics. Phenobarbital helps to reduce anxiety. It acts on the brain to produce a calming effect.

What does an antispasmodic drug do?

Antispasmodic: A medication that relieves, prevents, or lowers the incidence of muscle spasms, especially those of smooth muscle such as in the bowel wall.

How long does it take for antispasmodics to work?

How quickly do antispasmodics work? Antispasmodics usually work within an hour or so to ease symptoms. Their effectiveness may depend on the dose you are given and how often you take them.