Dicyclomine

Generic Name: Dicyclomine

Brand Names: Bentyl

Dicyclomine is an anticholinergic antispasmodic for irritable bowel syndrome (IBS) that reduces intestinal muscle spasms.

GastroenterologyIBSAntispasmodics

Drug Class

Anticholinergic Antispasmodic (Tertiary Amine)

Pregnancy

Category B — Animal reproduction studies have not demonstrated fetal risk, but adequate human studies are lacking. Dicyclomine is contraindicated in nursing mothers because reports of infant apnea have been associated with breast milk exposure.

Available Forms

Oral capsule (10 mg), Oral tablet (20 mg), Oral syrup (10 mg/5 mL), IM injection (10 mg/mL) — for short-term use only

What It's Used For

Irritable bowel syndrome (IBS) symptom relief
Functional gastrointestinal disorders
Abdominal cramping and spasms
Gastrointestinal smooth muscle relaxation

Dosage Quick Reference

These are general dosage guidelines. Your doctor will determine the appropriate dose for your specific situation.

Condition	Starting Dose	Maintenance Dose
Irritable bowel syndrome (adults)	20 mg orally 4 times daily	Increase to 40 mg 4 times daily after 1 week if tolerated; reassess at 2 weeks
Functional bowel/intestinal disorders	20 mg orally 4 times daily	20–40 mg 4 times daily; max 160 mg/day
Acute symptom flare (IM, hospital setting)	10–20 mg IM every 4–6 hours	Maximum 2 days of IM therapy; transition to oral
Elderly patients	10 mg orally 3–4 times daily	Use lowest effective dose; avoid per Beers Criteria when possible

Side Effects

Common Side Effects:

Dry mouth
Dizziness
Blurred vision
Nausea
Drowsiness
Weakness
Constipation
Difficulty urinating

Serious Side Effects (seek immediate medical attention):

Confusion or hallucinations (especially in elderly)
Rapid heartbeat or palpitations
Difficulty swallowing
Eye pain or visual changes
Inability to urinate
Severe abdominal bloating or pain
High fever with decreased sweating (heat stroke)

Drug Interactions

Dicyclomine has broad anticholinergic activity, and its interactions are largely additive with other medications that block acetylcholine or alter GI motility.

Other anticholinergic agents (e.g., diphenhydramine, oxybutynin, tricyclic antidepressants, paroxetine, antiparkinson agents): Additive anticholinergic burden increases the risk of confusion, urinary retention, constipation, dry mouth, and heat intolerance. Particularly hazardous in older adults — dicyclomine is included on the AGS Beers Criteria as potentially inappropriate.
Antacids: May reduce the absorption of dicyclomine. Separate doses by at least 1 hour.
Digoxin (oral solution): Reduced GI motility from dicyclomine can increase digoxin absorption and serum levels. Monitor for digoxin toxicity.
Metoclopramide: Has opposing effects (prokinetic vs. antispasmodic) and is pharmacologically antagonistic. Avoid concurrent use.
Potassium chloride (solid oral forms): Slowed GI transit increases the risk of GI ulceration from solid potassium formulations. Use liquid potassium when antispasmodics are required.
Alcohol and CNS depressants: Additive sedation and impaired psychomotor performance. Patients should be cautioned about driving and operating machinery.

Additional Information

Dicyclomine is an anticholinergic and antispasmodic medication used primarily to treat the symptoms of irritable bowel syndrome (IBS) and other functional gastrointestinal disorders. By relaxing smooth muscle in the gastrointestinal tract, it reduces painful cramping, bloating, and altered bowel habits that characterize these conditions.

Mechanism of Action

Dicyclomine exerts its therapeutic effects through two complementary mechanisms. First, it acts as a muscarinic receptor antagonist, blocking the action of acetylcholine on smooth muscle cells in the gastrointestinal tract. This reduces the involuntary muscle contractions that cause cramping and pain. Second, dicyclomine has a direct relaxant effect on smooth muscle, independent of its anticholinergic activity. This dual mechanism makes it effective for relieving the abdominal spasms and discomfort associated with IBS and other functional bowel disorders.

The anticholinergic properties of dicyclomine also affect other organ systems, which accounts for both additional therapeutic effects (such as reduced gastric acid secretion) and side effects (such as dry mouth and urinary retention).

Available Formulations

Dicyclomine (Bentyl) is available in several formulations to accommodate different patient needs. Oral capsules come in 10 mg strength, while oral tablets are available in 20 mg strength. An oral solution (10 mg/5 mL) provides flexibility for patients who have difficulty swallowing tablets or require dose adjustments. An injectable formulation (10 mg/mL) is available for intramuscular use in acute situations when oral administration is not possible.

FDA-Approved Indications

Dicyclomine is FDA-approved for the treatment of functional bowel/irritable bowel syndrome. While this is the primary labeled indication, the medication is also used off-label for various other conditions involving gastrointestinal smooth muscle spasm, including diverticulitis-associated pain, infantile colic, and as an adjunctive treatment in peptic ulcer disease.

Dosing Guidelines

For adults with IBS, the typical starting dose is 20 mg orally four times daily. After at least one week, if tolerated and if efficacy is not adequate, the dose may be increased to 40 mg four times daily. The medication should be taken before meals and at bedtime for optimal effect. If significant side effects occur, the dose should be reduced until a tolerable level is reached. The intramuscular formulation should not be used for more than 1-2 days, as oral administration should be initiated as soon as possible.

Therapeutic Considerations

Dicyclomine is most effective when used as part of a comprehensive IBS management strategy that includes dietary modifications, stress management, and lifestyle changes. The medication works best for IBS patients whose symptoms are dominated by cramping, pain, and urgency rather than constipation, as anticholinergic effects can worsen constipation. Patients should be counseled that the medication treats symptoms rather than the underlying condition and that some trial and adjustment may be needed to find the optimal dose.

Important Safety Considerations

Dicyclomine is contraindicated in infants younger than 6 months due to reports of serious respiratory symptoms, seizures, and death in this population. It should also be avoided in patients with obstructive uropathy, obstructive GI disease, severe ulcerative colitis, myasthenia gravis, and unstable cardiovascular status. Heat prostration can occur with use in hot environments due to decreased sweating. Elderly patients are particularly susceptible to anticholinergic effects and should be monitored closely.

Drug Interactions

Dicyclomine may interact with other anticholinergic medications, leading to additive effects and increased risk of adverse reactions. It can reduce gastric motility, potentially affecting the absorption of other oral medications. The medication should be used cautiously with drugs that slow GI motility (opioids) and with medications that have anticholinergic properties (antihistamines, tricyclic antidepressants, phenothiazines). Antacids may decrease dicyclomine absorption; separate administration by at least 2 hours.

Special Populations

Use in patients over 65 years requires caution due to increased sensitivity to anticholinergic effects, including confusion, constipation, and urinary retention. The medication should be used during pregnancy only if clearly needed, as safety has not been established. Dicyclomine passes into breast milk and may reduce milk production; use during breastfeeding requires careful consideration of benefits and risks.

Learn more at MedlinePlus

Frequently Asked Questions

Most patients notice some reduction in cramping within 1–2 hours of an oral dose. Full clinical benefit for chronic IBS symptom management typically develops over 1–2 weeks of consistent dosing. If you do not experience meaningful improvement after 2 weeks at an adequate dose, discuss alternatives with your provider.

Dicyclomine blocks muscarinic acetylcholine receptors throughout the body, not just in the gut. This produces predictable anticholinergic effects: reduced salivary secretion (dry mouth), pupil dilation and impaired focusing (blurred vision), reduced sweating, and slowed bladder emptying. Side effects are usually dose-related and may diminish with continued use.

The American Geriatrics Society Beers Criteria identify dicyclomine as potentially inappropriate in adults age 65 and older because of high anticholinergic burden, which is associated with confusion, falls, urinary retention, and dementia risk. When used in seniors, the lowest effective dose should be used for the shortest duration, and alternatives such as peppermint oil, hyoscyamine, or guideline-directed IBS therapies should be considered.

Alcohol amplifies the sedation and dizziness associated with dicyclomine and can worsen the dry mouth and blurred vision. Avoiding alcohol — especially when starting therapy or after dose changes — is recommended. If you choose to drink, limit intake and avoid driving or operating machinery.

Yes. Dicyclomine is contraindicated in narrow-angle glaucoma, urinary retention or obstructive uropathy, gastrointestinal obstruction, severe ulcerative colitis, myasthenia gravis, unstable cardiovascular status, and in nursing mothers. Tell your prescriber about all prior eye, urinary, GI, and cardiac conditions before starting therapy.

Questions to Ask Your Doctor

Consider discussing these topics at your next appointment:

✓Are there non-pharmacologic strategies — low-FODMAP diet, fiber, gut-directed CBT — that could reduce my need for dicyclomine?
✓How will we know whether dicyclomine is actually helping my symptoms?
✓Given my age and other medications, am I at higher risk for anticholinergic side effects?
✓Should I try a more targeted antispasmodic like hyoscyamine or peppermint oil first?
✓When and how should we attempt to taper or discontinue this medication?

Schedule an Appointment

Related Health Conditions

This medication is commonly used to treat or manage the following conditions:

Glaucoma

Glaucoma encompasses eye conditions damaging the optic nerve, often due to elevated eye pressure, leading to irreversible vision loss if untreated; early detection is crucial.

Learn More

Irritable Bowel Syndrome

Irritable Bowel Syndrome (IBS) is a chronic gut disorder characterized by abdominal pain, bloating, and altered bowel habits, potentially stemming from gut-brain interactions, infection, or food sensitivities.

Learn More

Ulcerative Colitis

Ulcerative colitis is a chronic inflammatory bowel disease causing ulcers and inflammation in the colon and rectum, driven by immune dysfunction, genetics, and environmental factors, leading to symptoms like diarrhea and abdominal pain.

Learn More

Medical Disclaimer: This information is for educational purposes only and should not be considered medical advice. Always consult with your healthcare provider before starting, stopping, or changing any medication. Your doctor can provide personalized recommendations based on your specific health condition and medical history.