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Hyoscyamine Sulfate

Pronunciation: hye-oh-SYE-a-mean
Class: Belladonna alkaloid

Trade Names

- Tablets 0.125 mg

- Tablets, orally disintegrating 0.125 mg

- Tablets 0.125 mg

- Tablets 0.375 mg

HyoMax FT
- Tablets, orally disintegrating 0.125 mg

HyoMax SL
- Tablet, sublingual 0.125 mg

- Tablets, extended-release 0.375 mg

- Elixir 0.125 mg/5 mL
- Solution, oral 0.125 mg/mL
- Solution 0.125 mg/5 mL
- Solution, concentrate 0.125 mg/mL

- Tablets, extended release 0.375 mg

- Injection 0.5 mg/mL
- Tablets 0.125 mg
- Tablets, orally disintegrating 0.125 mg

- Tablets, sublingual 0.125 mg

- Tablets, orally disintegrating 0.125 mg

- Tablets, orally disintegrating 0.125 mg

- Tablets, sustained release 0.375 mg


Inhibits the action of acetylcholine on structures innervated by postganglionic cholinergic nerves and on smooth muscles. These receptors are located in the autonomic effector cells of the smooth muscle, cardiac muscle, sinoatrial node, atrioventricular node, and exocrine glands. Inhibits GI propulsive motility and decreases gastric acid secretion. Controls excessive pharyngeal, tracheal, and bronchial secretions.



Distributed throughout the entire body.


Excreted unchanged in the urine within 12 h.

Indications and Usage

To control gastric secretion, visceral spasm, hypermotility in spastic colitis, spastic bladder, cystitis, pylorospasm, and associated abdominal cramps; to reduce symptoms of functional intestinal disorders such as those seen with mild dysentery, diverticulitis, and acute enterocolitis; treatment of infant colic; as a “drying” agent in rhinitis; to reduce rigidity and tremors, and to control sialorrhea and hyperhidrosis of Parkinson disease; with morphine or other narcotics for symptomatic relief of biliary and renal colic; poisoning by anticholinesterase agents; adjunct in treatment of peptic ulcer, irritable bowel syndrome, functional GI disorders, neurogenic bladder, and neurogenic bowel disturbances; preoperative to reduce secretions; block cardiac vagal inhibitory reflexes during anesthesia induction and intubation.


Glaucoma; obstructive uropathy; obstructive disease of the GI tract; paralytic ileus; intestinal atony in the elderly or debilitated; unstable CV status in acute hemorrhage; severe ulcerative colitis; toxic megacolon complicating ulcerative colitis; myasthenia gravis; myocardial ischemia.

Dosage and Administration


PO 0.125 to 0.25 mg every 4 h or as needed orally or sublingually (max, 12 tablets per 24 h), 0.375 to 0.75 mg in sustained-release form every 12 h (max, 4 tablets in 24 h).

Children (2 to 12 y of age)

PO 2.5 to 5 mL (0.031 to 0.125 mg) of 0.125 mg/5 mL solution every 4 h or as needed (max, 12 mL in 24 h).

Children (2 y of age and younger)

PO Dosing of 0.125 mg/mL drops (as based on body weight) every 4 h or as needed (max, 6 doses in 24 h) is:

Children's Dosing in Relation to Body Weight Body weight Usual dosage 2.3 kg 3 drops 3.4 kg 4 drops 5 kg 5 drops 7 kg 6 drops 10 kg 0.25 tsp (0.031 mg) or 8 drops 15 kg 11 drops 20 kg 0.5 tsp (0.063 mg) 40 kg 0.75 tsp (0.094 mg) 50 kg 1 tsp (0.125 mg) Adult

Subcutaneous / IM / IV 0.25 to 0.5 mg 2 to 4 times daily as needed.

General Advice

  • Take 30 to 60 min before meals.


Store at 68° to 77°F.

Drug Interactions


Antacids may interfere with absorption of hyoscyamine.

Antimuscarinics, such as amantadine, haloperidol, phenothiazines, MAOIs, tricyclic antidepressants, and some antihistamines

Additive anticholinergic effect when used with these drugs.

Adverse Reactions


Headache; nervousness; drowsiness; weakness; dizziness; confusion, insomnia; fever; excitability; restlessness; tremor; speech disturbance; ataxia.


Palpitations; tachycardia.


Allergic reactions; urticaria; rash; flushing.


Nasal congestion; altered taste; mydriasis; cycloplegia; blurred vision; increased ocular tension; loss of taste.


Xerostomia; nausea; vomiting; dysphagia; heartburn constipation, bloated feeling; paralytic ileus; dry mouth.


Urinary hesitancy and retention; impotence.


Suppressed lactation; decreased sweating.



Category C .


Excreted in human milk.


Use cautiously in infants. Not recommended for use in children younger than 6 y of age ( HyoMax tablets).


Use with caution; elderly patients are especially susceptible to adverse reactions.

Special Risk Patients

Use cautiously in patients with autonomic neuropathy, hyperthyroidism, coronary artery disease, CHF, cardiac arrhythmias, tachycardia, hypertension, renal disease, and hiatal hernia associated with reflux esophagitis.

Hazardous Tasks

Patients should avoid engaging in hazardous tasks requiring complete mental alertness.

Drug-induced psychosis

Drug-induced psychosis has been reported in sensitive patients.


Diarrhea may be an early sign of intestinal obstruction; hyoscyamine treatment would be inappropriate.

Dental effects

Prolonged use may decrease or inhibit salivary flow, thus contributing to the development of caries, periodontal disease, oral candidiasis, and discomfort.

Heat prostration

Heat prostration may occur at high environmental temperatures.



Blurred vision; CNS stimulation; dilated pupils; difficulty in swallowing; dizziness; dry mouth; headache; hot, dry skin; nausea; vomiting.

Patient Information

  • Advise patient to take dose 30 to 60 min before meals.
  • Advise patient that drug may cause drowsiness or impaired judgement or thinking skills, and to use caution while driving, riding a bike, or performing other tasks requiring mental alertness.
  • Advise patient to use caution during exercise or hot weather; overheating may result in heat stroke.

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