Drug information of Hyoscyamine


Hyoscyamine is a chemical compound, a tropane alkaloid it is the levo-isomer to atropine. It is a secondary metabolite of some plants, particularly henbane (Hyoscamus niger.) Hyoscyamine is used to provide symptomatic relief to various gastrointestinal disorders including spasms, peptic ulcers, irritable bowel syndrome, pancreatitis, colic and cystitis.

 It has also been used to relieve some heart problems, control some of the symptoms of Parkinson's disease, as well as for control of respiratory secretions in end of life care.

Mechanism of effect

Hyoscyamine competes favorably with acetylcholine for binding at muscarinic receptors in the salivary, bronchial, and sweat glands as well as in the eye, heart, and gastrointestinal tract. The actions of hyoscyamine result in a reduction in salivary, bronchial, gastric and sweat gland secretions, mydriasis, cycloplegia, change in heart rate, contraction of the bladder detrusor muscle and of the gastrointestinal smooth muscle, and decreased gastrointestinal motility.

Drug indications



Adults and pediatric patients 12 years of age and older:
 1 to 2 tablets every four hours or as needed. Do not exceed 12 tablets in 24 hours. 
Pediatric patients 2 to under 12 years of age:
½ to 1 tablet every four hours or as needed. Do not exceed 6 tablets in 24 hours.

Side effects

Insomnia , Diarrhea , Headache , nausea , dry mouth , vomiting , Blurred vision , vertigo , asthenia , urticaria , taste perversion , urinary retention , dry skin , hallucinations , decreased sweating , Restlessness , allergic reactions , Abdominal pain

dry mouth, urinary hesitancy and retention, blurred vision, tachycardia, palpitations, mydriasis, increased ocular tension, loss of taste, headache, nervousness, drowsiness, weakness, fatigue, dizziness, insomnia, nausea, vomiting, impotence, constipation, bloated feeling, abdominal pain, diarrhea, allergic reactions or drug idiosyncrasies, urticaria and other dermal manifestations, ataxia, speech disturbance, mental confusion and/or excitement (especially in geriatric patients), short-term memory loss, hallucinations, and decreased sweating.

Amantadine: Possible additive anticholinergic adverse effects
Antacids: Possible decreased absorption of antimuscarinic.
Antiarrhythmic agents (quinidine, disopyramide, procainamide): Possible additive anticholinergic adverse effects.
Antidepressants, tricyclic: Possible additive anticholinergic adverse effects.
Antihistamine agents (meclizine): Possible additive anticholinergic adverse effects.
Antiparkinsonian agents: Possible additive anticholinergic adverse effects.
Belladonna alkaloids: Possible additive anticholinergic effects.
Corticosteroids: Possible increased intraocular pressured.
CNS depressants (e.g., sedatives, tranquilizers, alcohol): Possible increased CNS depressive effects.
Glutethimide: Possible additive anticholinergic adverse effects.
Ketoconazole: Possible decreased ketoconazole absorption.
Levodopa: Possible increased gastric metabolism of levodopa and decreased levodopa absorption in the small intestine.
Meperidine: Possible additive anticholinergic adverse effects.
Phenothiazine: Possible additive anticholinergic adverse effects.
Potassium chloride: Antimuscarinics may potentiate potassium chloride's local GI mucosal effects.
Skeletal muscle relaxants: Possible additive anticholinergic adverse effects.


CNS Effects: Possible adverse CNS effects, including CNS depression, manifested as drowsiness, euphoria, amnesia, fatigue, and dreamless sleep; disorientation; confusion; memory disturbances; and dizziness. Excitement, restlessness, hallucinations, or delirium may paradoxically occur, especially when Hyoscyamine is used in the presence of severe Effect. May result in impairment of performance of activities requiring mental alertness, physical coordination, or visual acuity (e.g., operating machinery, driving a motor vehicle). Use caution with underwater sports participation; warn patients about possible disorientation. Use with caution in patients with autonomic neuropathy.
Ocular Effects: Possible increased intraocular pressure; monitor open-angle glaucoma therapy and adjust as necessary.
Idiosyncratic Reaction: Excessive susceptibility to the effects of Hyoscyamine occurs rarely. Toxic symptoms may occur with therapeutic doses. Most serious idiosyncratic reaction is acute toxic psychosis (e.g., confusion, agitation, rambling speech, hallucinations, paranoid behavior, delusions).
 Other manifestations may include marked CNS disturbances (e.g., complete disorientation, active delirium), somnolence, dilated pupils, accelerated pulse rate, and dryness of the mouth with a husky quality of the voice. Idiosyncratic reaction usually is reversed by physostigmine.
Withdrawal of Therapy: Possible drug withdrawal symptoms (e.g., nausea, vomiting, headache, dizziness, disturbances of equilibrium) following discontinuance of the transdermal system; usually do not appear until ≥24 hours after system removal.
Cardiovascular Effects: Possible tachycardia; use with caution in patients with tachyarrhythmias, CHF, CAD, or hyperthyroidism.
GI Effects : Possible decreased GI motility. Use with caution if pyloric or intestinal obstruction is suspected.
Down Syndrome, Spastic Paralysis, and Brain Damage

Possible increased sensitivity to antimuscarinic effects (e.g., mydriasis, positive chronotropic effect).

Respiratory Effects: Systemically administered antimuscarinics may reduce bronchial secretions and may lead to inspissation and formation of bronchial plugs in debilitated patients with chronic pulmonary disease; use with caution in such patients.
Seizure or Psychosis: Hyoscyamine may aggravate seizures or psychosis; use with caution in patients with a history of these conditions.

Pregnancy level


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