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Dicyclomine (Monograph)

Brand name: Bentyl
Drug class: Antimuscarinics/Antispasmodics
VA class: AU350
CAS number: 67-92-5

Medically reviewed by on Jun 21, 2022. Written by ASHP.


Dicyclomine hydrochloride is a synthetic tertiary amine antispasmodic.

Uses for Dicyclomine

GI Motility Disturbances

Has been used in the treatment of functional disturbances of GI motility such as irritable bowel syndrome.

Has limited efficacy in the treatment of these disorders and should be used only if other measures (e.g., diet, sedation, counseling, amelioration of environmental factors) have been of little or no benefit.

Has been used in combination with phenobarbital in the treatment of irritable bowel syndrome, but such combined therapy lacks substantial evidence of efficacy.


Has been used alone and in combination with phenobarbital in the treatment of acute enterocolitis [off-label], but the drug alone and the combination lack substantial evidence of efficacy.

Infant Colic

Has been used alone and in combination with phenobarbital in the treatment of infant colic [off-label], but the drug alone and in combination lack substantial evidence of efficacy.

Considered a benign, self-limiting condition that tends to resolve spontaneously and not require medical treatment.

Dicyclomine Dosage and Administration


Administer orally or by IM injection.

Do not administer by IV or subcutaneous injection.

Oral Administration

Usually administer orally.


Dilute oral solutions with an equal volume of water just prior to administration.

IM Injection

May be administered by IM injection when oral therapy is not feasible.

Oral therapy should replace IM therapy as soon as possible; do not use IM for longer than 1 or 2 days.

May produce local irritation and/or transient sensation of lightheadedness.


Available as dicyclomine hydrochloride; dosage expressed in terms of the salt.

Pediatric Patients

GI Motility Disorders

Infants >6 months of age [off-label]: 5 mg 3 or 4 times daily.

Children [off-label]: 10 mg 3 or 4 times daily.


GI Motility Disorders

Usual initial dosage: 20 mg 4 times daily; limit IM to 1 or 2 days.

Maintenance: Depending on response, increase dosage during the first week to 40 mg 4 times daily unless adverse effects limit upward titration.

Only 40 mg 4 times daily has been shown clearly to be effective, but associated with a substantial incidence of adverse effects.

Discontinue the drug if an adequate response is not obtained within 2 weeks or adverse effects limit dosage to <80 mg daily.


20 mg 4 times daily; limit IM to 1 or 2 days.

Prescribing Limits


GI Motility Disorders

Safety of 80–160 mg daily for longer than 2 weeks not established.

Special Populations

Hepatic Impairment

No specific hepatic dosage recommendations; use with caution.

Renal Impairment

No specific renal dosage recommendations; use with caution.

Geriatric Patients

No specific geriatric dosage recommendations; use with caution since they may be more susceptible to adverse effects.

Cautions for Dicyclomine


  • Obstructive uropathy.

  • Obstructive disease of the GI tract.

  • Severe ulcerative colitis.

  • Reflux esophagitis.

  • Unstable cardiovascular status in acute hemorrhage.

  • Glaucoma.

  • Myasthenia gravis.

  • Infants <6 months of age. (See Infant Risk under Warnings.)

  • Nursing women.

  • Known hypersensitivity to dicyclomine or any ingredient in the formulation.



CNS Effects

Psychosis in patients with increased sensitivity to anticholinergic drugs. CNS manifestations include confusion, disorientation, short-term memory loss, hallucinations, dysarthria, ataxia, coma, euphoria, decreased anxiety, fatigue, insomnia, agitation and mannerisms, and inappropriate affect.

CNS manifestations usually resolve within 12–24 hours after drug is discontinued.


May be an early sign of incomplete intestinal obstruction, especially in patients with ileostomy or colostomy; do not use in this instance since use would be inappropriate and possibly harmful.

Drowsiness and Blurred Vision

May cause drowsiness and blurred vision and impair functioning. (See Advice to Patients.)

Performance of activities requiring mental alertness and physical coordination may be impaired.

Thermoregulatory Effects

Exposure to high environmental temperatures may result in heat prostration due to decreased sweating. Increased risk of hyperthermia in patients who are febrile.

Infant Risk

Serious respiratory symptoms (dyspnea, shortness of breath, breathlessness, respiratory collapse, apnea, asphyxia), seizures, syncope, pulse rate fluctuations, muscular hypotonia, and coma in infants. Death has been reported, although no causal relationship between these effects observed in infants and dicyclomine administration has been established.

Major Toxicities


A curare-like action may occur (e.g,, neuromuscular blockade leading to muscular weakness and possible paralysis).

General Precautions

Concomitant Illnesses

Use with caution in patients with autonomic neuropathy, hepatic or renal disease, ulcerative colitis, hyperthyroidism, hypertension, CHD, CHF, cardiac tachyarrhythmia, hiatal hernia, orknown or suspected prostatic hyperplasia.

Cardiac Tachyarrhythmia

Investigate any tachycardia before administration since dicyclomine may increase heart rate.

Abuse Potential

Abuse and/or dependence for anticholinergic effects has been reported rarely.

Specific Populations


Category B.


Contraindicated in nursing women because of risk to infant. (See Infant Risk under Warnings.)

Pediatric Use

Contraindicated in infants <6 months of age. Serious, potentially fatal effects have occurred in infants. (See Infant Risk under Warnings.)

Safety and efficay in chlidren not established.

Hepatic Impairment

Use with caution.

Renal Impairment

Use with caution.

Common Adverse Effects

Most adverse effects are manifestations of pharmacologic effects at muscarinic-cholinergic receptors and usually are reversible when therapy is discontinued.

Severity and frequency of adverse effects are dose related and individual intolerance varies greatly; although adverse effects occasionally may be obviated by a reduction in dosage, this also will likely eliminate potential therapeutic effects. If dosage of ≥80 mg daily cannnot be achieved because of intolerance, discontinue dicyclomine.

Dry mouth, dizziness, blurred vision, nausea, light-headedness (especially with the injectable form), drowsiness, weakness, nervousness.

Interactions for Dicyclomine

Drugs with Anticholinergic Effects

Additive adverse effects resulting from cholinergic blockade (e.g., xerostomia, blurred vision, constipation). Advise of possibility of increased anticholinergic effects and monitor carefully.

Effects on GI Absorption of Drugs

By inhibiting the motility of the GI tract and prolonging GI transit time, antimuscarinics have the potential to alter GI absorption of various drugs.

Concurrent use of antimuscarinics and slow-dissolving tablets of digoxin may result in increased serum digoxin concentrations. This interaction can be avoided by using digoxin oral solution or tablets that dissolve rapidly (e.g., Lanoxin). Patients receiving an antimuscarinic and digoxin should be closely observed for signs of digitalis toxicity.

Because antimuscarinics may decrease gastric acid output and/or increase gastric pH, they may decrease the GI absorption of ketoconazole which depends on gastric acidity for dissolution and absorption. If concomitant therapy is necessary, the antimuscarinic should be given at least 2 hours after ketoconazole tablets.

Specific Drugs




Achlorhydria treatment drugs

Inhibitory effects of anticholinergic drugs on gastric hydrochloric acid secretion are antagonized by agents used to treat achlorhydria


Increased anticholinergic effects

Inform patient and monitor carefully


Decreased GI absorption of dicyclomine

Administer oral dicyclomine at least 1 hour before antacids

Antiarrythmic agents, Class I (quinidine)

May increase certain actions or adverse effects of dicyclomine

Anticholinergic drugs

Increased anticholinerigic effects

Inform patient and monitor carefully

Antidepressants, tricyclic

May increase certain actions or adverse effects of dicyclomine

Antiglaucoma agents

Dicyclomine may antagonize the effects of antiglaucoma agents.

Dicyclomine is contraindicated in glaucoma

Antihistamines (anticholinergic)

Increased anticholinerigic effects

Inform patient and monitor carefully

Antipsychotic agents (phenothiazines)

May increase certain actions or adverse effects of dicyclomine


May increase certain actions or adverse effects of dicyclomine


Increased IOP

Caution; monitor IOP

Dicyclomine is contraindicated in glaucoma

Digoxin (slow dissolving)

Incresaed serum digoxin

Use digoxin oral solution (elixir) or rapidly dissolving tablets (e.g., Lanoxin)


Antimuscarinics may antagonize the effects of drugs that alter GI motility

MAO Inhibitors

May increase certain actions or adverse effects of dicyclomine

Nitrates and nitrites

May increase certain actions or adverse effects of dicyclomine

Opiates (meperidine)

May increase certain actions or adverse effects of dicyclomine

Sympathomimetic agents

May increase certain actions or adverse effects of dicyclomine

Test, gastric secretion

Inhibitory effects on gastric hydrochloric acid secretion are antagonized by agents used to test gastric secretion

Dicyclomine Pharmacokinetics

Pharmacokinetics have not been fully determined.



Absorbed rapidly from the GI tract.

After single oral or IM doses, the relative oral bioavailability of the drug is about 67% of that following IM injection.

Absorption is slightly faster following IM injection than after oral administration.

Bioavailabilities of the oral solution, capsules, and tablets are equivalent.

Plasma Concentrations

Average peak: Within 1–1.5 hours after oral administration.

Solutions, peak: About 1 hours.

Capsules, peak: About 1.1 hours.

Tablets, peak: About 1.5 hours


Plasma concentrations decline in a biphasic manner.



Elimination Route

About 80% of a dose is eliminated in urine and about 10% in feces.


Initial distribution phase: About 1.8 hours.

Terminal elimination phase: About 9–10 hours.



Unstable in alkaline media and is readily converted to the free base in such media when moisture is present.

Store in containers protecting them from excessive heat, light, and moisture.


Capsules and Tablets

Well-closed containers at room temperature, preferably <30°C.


Room temperature, preferably <30°C; avoid exposure to excessive heat.



Room temperature, preferably less than 30°C; do not freeze.


For information on systemic interactions resulting from concomitant use, see Interactions.

Stable at pH 2–6.5.

Unstable at pH >7; at these alkaline pHs, precipitation of the free base may occur.


  • Releieves smooth muscle spasm of the GI tract.

  • Exact mechanism(s) of action not been established; appears to act as nonselective smooth muscle relaxant.

  • May have a nonspecific direct action on smooth muscle.

  • Generally has little or no antimuscarinic activity, except at high doses, and little or no effect on gastric secretion.

Advice to Patients

  • Potential for drug to impair mental alertness or physical coordination; avoid driving or operating machinery until effect on individual are know.

  • Advise patients of possible blurred vision with the drug; activities that require good, clear vision should be avoided.

  • Advise of risk of hyperthermia and heat prostration; avoid exposure to high environmental temperatures and avoid use when febrile.

  • Importance of informing clinicians of existing or contemplated concomitant therapy, including prescription and OTC drugs.

  • Importance of women informing clinicians if they are or plan to become pregnant or plan to breast-feed.

  • Importance of informing patients of other important precautionary information. (See Cautions.)


Excipients in commercially available drug preparations may have clinically important effects in some individuals; consult specific product labeling for details.

Please refer to the ASHP Drug Shortages Resource Center for information on shortages of one or more of these preparations.

* available from one or more manufacturer, distributor, and/or repackager by generic (nonproprietary) name

Dicyclomine Hydrochloride


Dosage Forms


Brand Names




10 mg*



Dicyclomine Hydrochloride Capsules

Lannett, Mylan, UDL, United Research, Watson, West-Ward


10 mg/5 mL*

Bentyl Syrup (with parabens and propylene glycol)


Dicyclomine Hydrochloride Syrup



20 mg*



Dicyclomine Hydrochloride Tablets

Lannett, Mylan, UDL, Watson, West-Ward


Injection, for IM use only

10 mg/mL

Bentyl (preservative-free)


AHFS DI Essentials™. © Copyright 2023, Selected Revisions July 1, 2006. American Society of Health-System Pharmacists, Inc., 4500 East-West Highway, Suite 900, Bethesda, Maryland 20814.

† Off-label: Use is not currently included in the labeling approved by the US Food and Drug Administration.

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