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hyoscyamine

Belladonna alkaloid, muscarinic antagonist · Anticholinergic

Belladonna alkaloid, muscarinic antagonistAnticholinergicATC A03BA03
CDSCO approvedATC A03BA03
EXCRETION
not curated
INTERACTIONS
4 major
SEVERE in our sources
PREGNANCY
not curated
Top interactions
  • Potassium ChlorideSevereDatabaseDDInter
  • Potassium CitrateSevereDatabaseDDInter
  • TopiramateSevereDatabaseDDInter
  • ZonisamideSevereDatabaseDDInter

Mechanism

Not yet extracted

Indications

Diarrhea-predominant irritable bowel syndrome (IBS)Increased tone and motility of the GI tract (spasticity)Diarrhea associated with irritation of the lower bowel (e.g., mild dysenteries, diverticulitis)IBS (to prevent pain and fecal urgency)

Dosing

Adult
Sublingual tablets, orally disintegrating tablets, immediate-release oral capsules, tablets, elixir, and drops: 0.125–0.25 mg every 4 h as needed. Extended-release forms: 0.25–0.375 mg every 12 h, or 0.375 mg every 8 h, as needed. Injection (IM, IV, SC): 0.25–0.5 mg every 4 h as needed.

Contraindications

  • Urinary tract obstruction
  • GI obstruction
  • Uncontrolled angle-closure glaucoma
  • Benign prostatic hyperplasia (use with extreme caution)
  • Colitis
  • Reflux esophagitis
  • Bowel obstruction

Side effects

Common
Antimuscarinic adverse effects similar to atropineDry mouthConstipationBlurred visionGastrointestinal discomfortCognitive impairmentDizzinessNausea

Drug interactions

Potassium Chloride
Severe
Database

.

Source: DDInter

Potassium Citrate
Severe
Database

Clinical effect not specified

Source: DDInter

Topiramate
Severe
Database

.

Source: DDInter

Zonisamide
Severe
Database

Clinical effect not specified

Source: DDInter

8 additional low-confidence interactions hidden — those rows lack a documented mechanism or management plan in our sources.

Related guidelines

Ask House about hyoscyamine

Continue into a citation-backed clinical answer with the drug context already attached.

Sources: Goodman & Gilman 14e·Verified: 2026-05-10 · House clinical team