Hyoscyamine is also known by the brand name Levsin. It is most commonly used to treat GI or bladder spasms or as adjunct treatment for IBS, PUD, and colic. It is also used in the treatment of rhinitis. It comes in a wide variety of dosage forms with the most common strengths being 0.125 mg and 0.375 mg. A common dosing regimen is between 0.125 mg - 0.25 mg every 4 hours as needed. The 0.375 mg dose is most commonly used with extended release formulations and dosed every 8-12 hours. Common side effects are xerostomia, dry eyes, dizziness, fever, blurred vision, and insomnia. There is a risk for fever or heat stroke especially when exercising or if in high heat environments.