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Dicyclomine Hydrochloride - Indications, Dosage, and Side Effects

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Dicyclomine hydrochloride is an antimuscarinic agent used to treat IBS (irritable bowel syndrome). Read the article to learn more about Dicyclomine hydrochloride.

Medically reviewed by

Dr. Jagdish Singh

Published At April 20, 2023
Reviewed AtAugust 29, 2023


Dicyclomine hydrochloride is an M1, M2, and M3 antagonist and a non-competitive inhibitor of histamine, which is used to treat functional bowel disorder and irritable bowel syndrome. Dicyclomine was approved by FDA (Food and Drug Administration) in 1950. It works by slowing the natural movements of the gut and relaxing the muscles in the stomach and intestines.

Indication of Dicyclomine Hydrochloride:

  • Dicyclomine hydrochloride is indicated for a patient with functional or irritable bowel syndrome.


  • Dose Form: Capsules, tablets, syrup, and injections.

  • Dose Strength: Capsules - 10 mg, syrup - 10 mg/5mL, injection - 10 and 20 mg/mL, tablets - 20 mg.

  • Dicyclomine is adjusted according to the patient's needs.


Oral in Adults:

  • Start the dose with 20 mg four times a day. After a week, the dose is raised to 40 mg four times a day.

  • Discontinue Dicyclomine with a dose of fewer than 80 mg daily after two weeks of treatment.

Intramuscular in Adults:

  • Intramuscular injection is recommended for no longer than one to two days when the patient cannot take the dose orally.

  • The recommended intramuscular dose is 10 to 20 mg four times daily.

Contraindications of Dicyclomine Hydrochloride:

  • Infants younger than six months of age.

  • Nursing mothers.

  • Patients with unstable cardiovascular status in cases of bleeding.

  • Myasthenia gravis.

  • Patients who are already suffering from glaucoma.

  • Patients who have obstructive uropathy.

  • The patient is dealing with obstructive gastrointestinal disease.

  • Patient with severe ulcerative colitis.

  • Patient with reflux esophagitis.

Warning and Precautions:

  • Intramuscular injection administration should never be done intravenously because it can cause thrombosis or thrombophlebitis over the injection site.

  • Cardiovascular Disease Patients - Dicyclomine is used cautiously in patients dealing with cardiovascular diseases like congestive heart failure and thyrotoxicosis. So, special care is required for patients with coronary diseases, ischemia, infarction, or hypertension.

  • Peripheral and Central Nervous System - Dicyclomine can cause dry mouth and skin, difficulty swallowing and talking, dilation of pupils, decreased bronchial secretions, increased urination, and affects the tone and motility of the gastrointestinal tract; these are the effects of inhibition on muscarinic receptors. Dicyclomine can also cause drowsiness, dizziness, and blurred vision.

  • Myasthenia Gravis - It is avoided in patients who have myasthenia gravis, as its over-usage can cause muscle weakness.

  • Intestinal Obstruction - DIarrhea is a common symptom of intestinal obstruction in patients of colostomy and ileostomy.

  • Toxic Dilation of Intestine Megacolon - It usually occurs when patients with dysentery are administered Dicyclomine.

  • Ulcerative Colitis - Dicyclomine is used cautiously in patients with ulcerative colitis as the drug can suppress intestinal motility.

  • Prostatic Hypertrophy - Dicyclomine is used cautiously in suspected prostatic hypertrophy patients.

  • Hepatic and Renal Impairments - It is used cautiously in renal and hepatic disease patients.

  • Geriatric Population - Older people are more suspected of the adverse effects. Hence cautious use of Dicyclomine is required in them.

Special Considerations:

  • Pregnancy - There are no concluded results to the study performed on Dicyclomine hydrochloride usage in pregnant women. Although the study of Dicyclomine on rats has presented no evidence for the fetus, the use of Dicyclomine should still be done cautiously in pregnant women.

  • Nursing Mothers - Dicyclomine is contraindicated in nursing mothers because it is excreted in their milk and shows adverse reactions to the baby being fed.

  • Pediatric Use - The safety and effectiveness are not determined in child patients. However, Dicyclomine is contraindicated in infants younger than six months of age.

  • Geriatric Use - Special care is taken while having Dicyclomine for elderly patients as they have decreased renal functions.

  • Renal Impairments - The safety and effectiveness are not established for Dicyclomine in renal patients.

  • Hepatic Impairments - Cautious use of Dicyclomine is done in hepatic patients as no safety and efficacy have been established till now.

For Patients:

What Is the Use of Dicyclomine Hydrochloride?

Dicyclomine is used to treat irritable bowel syndrome. It is used because it relieves muscle spasms in the gastrointestinal tract by blocking the activity of natural substances in the body.

How Is Dicyclomine Taken?

Dicyclomine is available in capsules, tablets, or syrup, taken orally. It's taken four times a day. Take the dose as prescribed by the doctor and gradually increase it. Do not take a dose more or less than recommended.

What Are the Precautions Taken While Having Dicyclomine?

  • The patient should avoid Dicyclomine if they are allergic to it.

  • The patient should inform the doctor about the other medications that they are taking.

  • If the patient is suffering from glaucoma, swelling of the colon's lining (ulcerative colitis), enlarged prostate, difficulty urinating, heartburn, myasthenia gravis (muscle weakness), hyperthyroidism, heart failure, hernia, or nerve diseases; then the patient should avoid Dicyclomine.

  • The patient who is pregnant and breastfeeding should also avoid Dicyclomine medicine.

  • Older aged patients should also take medicine with caution.

  • Avoid going for any surgery or dental surgery while taking medicine.

  • The patient should avoid driving after taking Dicyclomine medicine.

  • Alcohol should also be avoided as it can increase the patient's drowsiness.

  • Dicyclomine medicine can cause heat strokes and fever at high temperatures, decreasing the ability to cool off by sweating.

What if the Regular Dose of Dicyclomine Got Missed?

If the regular dose of Dicyclomine got missed, then take the medicine soon. And if the timing of the next dose is near, then take the next dose and skip the previous missed dose. The patient should not take a double dose at the same time.

What Are the Side Effects of Dicyclomine Medicine?

Side effects of Dicyclomine are

  • Dry mouth.

  • Upset stomach.

  • Vomiting.

  • Constipation.

  • Gas or bloating.

  • Dizziness.

  • Headache.

  • Drowsiness.

  • Double vision.

  • Difficulty in urinating.

  • Weakness.

  • Loss of appetite.

  • Tinglingness.

  • Blurred vision.

Some severe side effects require medical attention by the doctor immediately.

They are

  • Hot, flushed, dry skin.

  • Confusion.

  • Forgetfulness.

  • Unsteadiness.

  • Coma.

  • Anxiety.

  • Tiredness.

  • Difficulty in falling asleep.

  • Mood changes.

  • Muscle weakness.

  • Rapid or pounding heartbeat.

  • Fainting.

  • Hives.

  • Skin rash.

  • Itchiness.

  • Difficult breathing.

  • Difficulty in swallowing.

How to Store or Dispose of the Medicine?

Dicyclomine medicine is stored in a tightly closed container and at room temperature, away from the reach of the children. It should be kept away from excess heat and moisture.

The unrequired medicine is disposed of in a particular way so that no pets, children, or other people unknowingly take medicine. The medicine that is not required anymore should not be flushed into the toilet; instead, dispose of the medicine should go through the take-back program. The patient can also learn about the take-back program on FDA (Food and Drug Administration) site.

What Are the Symptoms After the Overdosage of Dicyclomine?

Symptoms that develop on overdosage are

  • Headache.

  • Upset stomach.

  • Vomiting.

  • Blurred vision.

  • Dilated pupil.

  • Hot, dry skin.

  • Dry mouth.

  • Difficulty in swallowing.

  • Nervousness.

  • Excitement.

  • Hallucinations (seeing things that do not exist).

For Doctors:

Dicyclomine Hydrochloride:

Dicyclomine hydrochloride is an antispasmodic and anticholinergic or antimuscarinic agent. Its chemical name is [bicyclohexyl]-1-carboxylic acid,2-(diethylamino) ethyl ester, hydrochloride, and it has a molecular formula of C19H35NO2.HCl with a molecular weight of 345.95. It has a fine, white, crystalline, odorless powder with a bitter taste. It is soluble in water and freely soluble in alcohol and chloroform. And very slightly soluble in ether.

What Is the Indication of Dicyclomine?

Dicyclomine is indicated for the treatment of functional bowel or irritable bowel syndrome.

What Is the Clinical Pharmacology of Dicyclomine?

Mechanism of Action:

Dicyclomine relaxes the smooth muscle spasms of the gastrointestinal tract. It acts partially through the direct antimuscarinic activity of M1, M3, and M2 receptors and partially through the antagonism of Bradykinin and Histamine. Dicyclomine is a non-competitive inhibitor of bradykinin and histamine that directly acts on smooth muscles and decreases the strength of the contraction seen in spasms of the ileum.


Dicyclomine blocks the secretion of saliva and sweat, decreases gastrointestinal secretions and motility, causes drowsiness, dilates pupils, increases heart rate, and depressive motor function.


  • Absorption - Dicyclomine rapidly gets absorbed after oral administration. It reaches its peak value in 60 to 90 minutes.

  • Distribution - The volume of distribution for 20 mg oral dose is 3.65 L/kg which provides extensive tissue distribution.

  • Elimination - Dicyclomine is eliminated 79.5 percent in urine and 8.4 percent in feces.

  • Half-Life - Half-life is approximately 1.8 hours.

What Is the Non-clinical Toxicology of Dicyclomine?

Carcinogenesis: There is no data present related to the carcinogenic effect of Dicyclomine.

Mutagenesis: No results are present related to a mutation on the usage of Dicyclomine.

Impairment of Fertility: The studies on rats have proved no effects on conception or breeding using Dicyclomine.

What Are the Dosage and Administration of Dicyclomine?


Dosage Form and Strengths:

Dicyclomine capsules are available in 10 mg.

Dicyclomine tablets are available in 20 mg.

Dicyclomine syrup is available in 10 mg/5 mL.

Dicyclomine injections are available in 20 mg/2 mL.

Dosages are adjusted to individual patient needs.


Oral Dosage and Administration in Adults: The recommended initial dose is 20 mg, given four times daily. And after the initial dose is increased to 40 mg given four times a day.

If the results are not acquired within two weeks, or side effects occur due to the dose, it is discontinued as no safety is present for two weeks.

Intramuscular Dosage and Administration in Adults: Dicyclomine injection is administered only by intramuscular route. Any other route should not administer because it causes thrombosis. The recommended dose is 10 to 20 mg, delivered four times a day, but the injection is delivered for one to two days.

Dosage Supply and Storage:

Capsules are supplied in 100 bottles and stored at room temperature below 86 degrees Fahrenheit.

Tablet - They are light blue and supplied in a bottle of 100. They are prevented from direct sunlight and stored at room temperature below 86 degrees Fahrenheit.

Syrup - They are supplied as pink color 16 ounces bottle and stored at room temperature below 86 degrees Fahrenheit.

Injection - They are supplied in the box of five 20 mg/2 mL ampules. They are stored at room temperature below 86 degrees Fahrenheit. They are protected from freezing.

Adverse Reactions of Dicyclomine Hydrochloride:

  • Gastrointestinal Reaction - Anorexia.

  • Central Nervous System - Tingling, numbness, dyskinesia, speech disturbance, insomnia.

  • Peripheral Nervous System - Muscle weakness, paralysis.

  • Ophthalmologic Changes - Diplopia, increased ocular tension.

  • Dermatologic Changes - Urticaria, itchiness, other dermal issues.

  • Genitourinary - Urinary hesitancy, urinary retention in prostate hypertrophy patients.

  • Cardiovascular - Hypertension.

  • Respiratory - Apnea.

  • Others - Decreased sweating, sneezing, throat congestions, impotence.

Drug Interactions:

  • Antiglaucoma Agents - Dicyclomine is not used along with antiglaucoma agents because it can increase intraocular pressure.

  • Other Drugs with Anticholinergic Effects - These drugs show activity that can increase anticholinergic drugs' actions and side effects, like Amantadine, Benzodiazepines, antipsychotic drugs, and nitrates.

  • Other Gastrointestinal Motility Drugs - There are interactions with other gastrointestinal motility drugs that alter gastrointestinal motility, like Metoclopramide.

  • Effects of Antacids - Antacids can interfere with the absorption of anticholinergic agents like Dicyclomine.

  • Effects on Absorption with Other Drugs - Drugs like Digoxin can cause slow dissolving effects of Dicyclomine.

  • Effect on Gastric Acid Secretion - The inhibition effects of Dicyclomine on gastric hydrochloric acid secretion antagonists to treat achlorhydria and gastric secretion.


If the patient has an overdose, then the patient should consult the emergency room. The symptoms related to overdosage are:

  • Headache.

  • Nausea.

  • Vomiting.

  • Blurred vision.

  • Difficulty in swallowing.

  • Dizziness.

  • Dilated pupil.

  • Central nervous system stimulation.

  • Convulsions.

  • Dry skin.

  • Muscular weakness.

  • Paralysis.

Clinical Trials:

Controlled studies have been performed on 100 patients who were delivered Dicyclomine. These patients were already suffering from functional bowel or irritable bowel syndrome. The initial dose was 160 mg which was 40 mg given four times a day. Among all, 82 percent were treated with Dicyclomine hydrochloride. However, 9 percent of patients discontinued Dicyclomine hydrochloride because of side effects, compared with 2 percent in the placebo group. In this, 41 percent of patients who have side effects, their side effects disappeared or were tolerable with a 160 mg daily dose without any need for reduction. But 46 percent of patients with side effects have to reduce the dose to 90 mg, so their side effects can be tolerable or disappear. It was demonstrated that the clinical response when compared with placebo (p<0.05); 55 percent were treated well with Dicyclomine hydrochloride.

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Dr. Jagdish Singh
Dr. Jagdish Singh

Medical Gastroenterology


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