Section 19 · Monograph
Hyoscyamine
Reviewed Nov 2026FDA label
Levsin / LevbidAnticholinergic
- Forms
- Tab: 0.125mg | SL tab: 0.125mg | ODT: 0.125mg | ER: 0.375mg | Soln: 0.125mg/mL | Inj: 0.5mg/mL
- Dose
- Sialorrhea or secretions: 0.125-0.25mg SL/PO every 4h as needed (max 1.5mg/day)
- MOA
- Muscarinic receptor antagonism
Indications
- Adjunctive therapy for peptic ulcer, irritable bowel syndrome, spastic bladder, drooling and cholinergic poisoning/excess secretionsFDA-labeled
Mechanism of Action
- Tertiary antimuscarinic that reduces salivary, bronchial and gastrointestinal secretions and smooth-muscle spasm
Full Dosing
Adult / usual
- Sialorrhea or secretions: 0.125-0.25mg SL or PO every 4 hours as needed; maximum 1.5mg/day (immediate release)
- Extended-release 0.375mg every 12 hours
Renal
- Reduce dose in older adults and renal impairment
Contraindications
- Glaucoma
- Obstructive uropathy, obstructive GI disease, paralytic ileus, intestinal atony, severe ulcerative colitis
- Myasthenia gravis
- Unstable cardiovascular status
Drug Interactions
- Other anticholinergics: additive effects
- Cholinesterase inhibitors oppose effects; antacids may reduce absorption
Adverse Effects
- Dry mouth, blurred vision
- Urinary retention and constipation
- Tachycardia, flushing
- Confusion and delirium in older adults
Monitoring Parameters
- Mental status
- Urinary and bowel function
- Secretion control
Pregnancy & Lactation
- Limited data; use if benefit justifies risk
- Excreted in milk; may suppress lactation