Dicyclomine Side Effects: What to Expect and When to Call Your Doctor

Dicyclomine is effective for relieving the abdominal cramping of irritable bowel syndrome, but like all anticholinergic medications, it comes with a predictable set of side effects. Knowing what to expect — and what crosses the line from tolerable into serious — can help you manage your treatment with confidence.

Why Does Dicyclomine Cause Side Effects?

Dicyclomine works by blocking muscarinic acetylcholine receptors throughout the body — not just in the gut. While this is exactly what relieves IBS cramping, the same mechanism affects other body systems too: salivary glands (causing dry mouth), eyes (causing blurred vision), sweat glands (reducing sweating), bladder muscle (causing urinary hesitancy), and the brain (causing drowsiness or confusion in some people).

Common Side Effects (More Than 5% of Patients)

These are the side effects reported by more than 5% of patients in clinical trials. They're typically mild and often improve as your body adjusts to the medication:

Dry mouth: The most common side effect. Sipping water frequently, chewing sugar-free gum, or using saliva substitutes can help.

Dizziness: May occur especially when standing up quickly (orthostatic). Rise slowly from sitting or lying positions.

Blurred vision: Caused by the effect on eye muscles (cycloplegia and mydriasis). Avoid driving until you know how dicyclomine affects your vision.

Nausea: Some patients experience nausea, especially at the start of treatment. Taking dicyclomine with food may help.

Drowsiness/somnolence: Some patients feel sleepy, especially at higher doses. Avoid driving or operating machinery until you know how the medication affects you.

Weakness (asthenia): A general feeling of tiredness or low energy may occur.

Nervousness: Some patients report a jittery or nervous feeling.

Serious Side Effects: When to Call Your Doctor Immediately

These side effects are less common but require prompt medical attention. Stop taking dicyclomine and contact your doctor or go to the emergency room if you experience:

Fast, slow, or irregular heartbeat (palpitations/arrhythmia): Anticholinergic effects can initially cause a brief slowing of heart rate followed by tachycardia.

Confusion, hallucinations, or agitation: Anticholinergic-induced psychosis can occur, particularly in elderly patients. Signs usually resolve within 12–24 hours of stopping the medication.

Heat stroke (fever, hot and dry skin, no sweating): Dicyclomine reduces sweating. In hot environments, your body may overheat. Move to a cool environment, hydrate, and seek medical care immediately if you have fever with dry skin and no sweating.

Difficulty urinating: Urinary retention is a known anticholinergic effect. If you're unable to urinate, contact your doctor.

Severe allergic reaction: Hives, difficulty breathing, swelling of the face, lips, tongue, or throat require immediate emergency care.

Worsening of intestinal symptoms (paralytic ileus): At high doses, dicyclomine can suppress intestinal motility, leading to severe constipation or ileus. Call your doctor if your abdominal symptoms significantly worsen while taking dicyclomine.

Side Effects in Special Populations

Some groups are at higher risk for dicyclomine side effects:

Elderly patients: More sensitive to anticholinergic effects including confusion, urinary retention, and falls. The Beers Criteria lists dicyclomine as potentially inappropriate for patients 65 and older.

Infants under 6 months: Dicyclomine is absolutely contraindicated. Deaths, respiratory depression, and seizures have been reported.

Breastfeeding mothers: Dicyclomine passes into breast milk and is contraindicated while breastfeeding.

Tips for Managing Common Side Effects

Dry mouth: Sip water frequently throughout the day; use sugar-free gum or lozenges; avoid caffeine and alcohol

Dizziness: Rise slowly from sitting/lying; avoid standing rapidly; hold onto a railing when getting up

Blurred vision: Avoid night driving until your vision adjusts; discuss with your eye doctor if you have glaucoma

Heat intolerance: Stay cool; avoid saunas, hot tubs, and strenuous activity in heat; hydrate well

Side Effects vs. Effectiveness: When to Stop

If you experience intolerable side effects or if dicyclomine doesn't provide relief after 2 weeks at an adequate dose, your doctor may recommend discontinuing it. The FDA labeling recommends stopping if efficacy is not achieved within 2 weeks or if side effects require doses below 80 mg/day. See our guide on alternatives to dicyclomine if you need a different option.