Antispasmodics (e.g., dicyclomine, hyoscyamine)


How it works: They work by relaxing the smooth muscle in the colon, which reduces spastic contractions.

Which symptoms does it help: Belly pain.

How long it takes to see a benefit: Within 1 day.

FDA approved: N/A

Dosage: Dicyclomine – 20 mg; hyoscyamine regular release – 0.125 mg to 0.25 mg; hyoscyamine extended release – 0.375 mg to 0.75 mg

Special considerations or risks: Cannot be given to those who have a bowel blockage.

Most common side effects: Dizziness, drowsiness, blurred vision, nausea, and dry mouth.

Recommendation: ACG suggests certain antispasmodics (otilonium, pinaverium, hyoscine, cimetropium, drotaverine, and dicyclomine) for overall symptom improvement in IBS patients. (Recommendation: weak; Quality of evidence: very low)