Does dicyclomine cause constipation? How an IBS medication affects bowel movements

October 8, 2025 •

4 min read

As an anticholinergic medication, dicyclomine lists constipation as a possible side effect in clinical studies. This article explores why this medication, often used for irritable bowel syndrome (IBS), can cause constipation and provides strategies for managing this specific side effect.

Quick Summary

Dicyclomine, an anticholinergic antispasmodic, can cause constipation by slowing intestinal muscle contractions. Managing this requires a discussion with your doctor, as alternatives may be better suited for constipation-predominant IBS.

Key Points

Mechanism of Action: Dicyclomine is an anticholinergic medication that relaxes muscles in the intestines by blocking acetylcholine, the natural chemical that causes contractions.
Effect on Bowel Movements: The relaxation of intestinal muscles directly slows down the movement of food and waste, leading to the common side effect of constipation.
IBS Subtype Consideration: This side effect can be beneficial for those with diarrhea-predominant IBS (IBS-D), but it makes dicyclomine a less suitable option for individuals with constipation-predominant IBS (IBS-C).
Risk Factors: Older adults and individuals taking other anticholinergic medications have an increased risk of experiencing or worsening constipation with dicyclomine.
Management Strategies: Constipation can often be managed through increased fluid intake, higher dietary fiber, and regular exercise, but a doctor should be consulted for persistent issues.
Alternative Treatments: Various other IBS medications exist, some specifically designed to relieve constipation (like Lubiprostone or Linaclotide), which may be better for certain patients.

Understanding Dicyclomine and Its Role in IBS

Dicyclomine, also known by the brand name Bentyl, is a prescription medication primarily used to manage symptoms of irritable bowel syndrome (IBS). It is categorized as an antispasmodic, meaning it helps to relieve the painful muscle spasms and cramping that occur in the gastrointestinal (GI) tract. By relaxing the smooth muscles of the stomach and intestines, dicyclomine aims to provide symptomatic relief for conditions of the lower and middle intestines.

The Mechanism Behind Dicyclomine's Effect on Constipation

The reason dicyclomine can cause constipation is directly linked to its primary mechanism of action as an anticholinergic drug.

Blocks Acetylcholine: Dicyclomine works by blocking the action of acetylcholine, a neurotransmitter that plays a key role in stimulating muscle contractions throughout the body, including the digestive system.
Slows Gut Motility: When acetylcholine's activity is diminished, the smooth muscles of the intestines relax and the overall movement (motility) of the gut slows down.
Causes Hard Stool: This slowed transit time gives the large intestine more opportunity to reabsorb water from the waste material. The longer the waste sits in the colon, the more water is reabsorbed, resulting in harder, drier stool that is more difficult to pass.

For some individuals with diarrhea-predominant IBS, this slowing effect might be a desirable outcome. However, for those with constipation-predominant IBS (IBS-C) or mixed-type IBS, this unintended consequence can exacerbate their existing bowel problems.

Managing Constipation from Dicyclomine

If you experience constipation while taking dicyclomine, several management strategies can help. It is important to discuss these with your healthcare provider before implementing them.

Increase Dietary Fiber: Gradually increasing your fiber intake can help soften stool and promote regular bowel movements. Opt for fiber-rich foods like whole grains, fruits, and vegetables. A psyllium-based fiber supplement might also be effective.
Stay Hydrated: Drinking plenty of fluids, especially water, is crucial to prevent dehydration, which can worsen constipation. Adequate hydration helps keep stool soft and easier to pass.
Regular Exercise: Physical activity helps stimulate intestinal contractions and promotes regular bowel function. Even a moderate daily walk can make a difference.
Over-the-Counter Laxatives: For persistent constipation, your doctor might approve the use of an osmotic laxative, such as polyethylene glycol (MiraLAX). It is important to avoid certain laxatives, like mineral oil-based or bulk-forming agents, without medical guidance.

Dicyclomine vs. Other IBS Medications: Impact on Bowel Habits

When considering treatment for IBS, particularly for those concerned about constipation, it's helpful to compare dicyclomine with other available medications. The table below outlines how different treatments affect bowel function.


Medication	Class	Effect on Bowel Motility	Primary Indication	Potential for Constipation
Dicyclomine (Bentyl)	Anticholinergic/Antispasmodic	Slows Motility	IBS spasms (may worsen IBS-C)	High
Lubiprostone (Amitiza)	Chloride Channel Activator	Increases intestinal fluid and motility	IBS-C	Low (may cause diarrhea)
Linaclotide (Linzess)	Guanylate Cyclase-C Agonist	Increases intestinal fluid and motility	IBS-C	Low (may cause diarrhea)
Loperamide (Imodium)	Peripheral Opioid Agonist	Slows Motility	Diarrhea-predominant IBS (IBS-D)	High (desired effect)
Eluxadoline (Viberzi)	Mu-Opioid Receptor Agonist/Delta-Opioid Antagonist	Slows Motility	Diarrhea-predominant IBS (IBS-D)	Moderate (may cause constipation)

Who Should Be Cautious with Dicyclomine?

Because of its anticholinergic properties, certain groups of people should be especially cautious when taking dicyclomine, or consider alternative treatments entirely.

Individuals with Constipation-Predominant IBS (IBS-C): The constipating effect of dicyclomine can counteract the primary goal of treatment for those with IBS-C and may worsen their symptoms.
Older Adults: Seniors are more sensitive to the side effects of anticholinergic medications, including cognitive issues like confusion and memory loss, in addition to constipation.
Pre-existing Conditions: Dicyclomine is contraindicated or should be used with caution in patients with conditions such as glaucoma, obstructive uropathy (trouble urinating), severe ulcerative colitis, and other conditions affecting the heart or kidneys.
Interactions with Other Drugs: Taking dicyclomine with other anticholinergic medications can increase the risk of side effects. It may also interact with antacids, reducing its effectiveness.

Conclusion

Does dicyclomine cause constipation? Yes, it is a known and common side effect due to the medication's anticholinergic mechanism, which slows intestinal motility. While this may be a desirable effect for some patients with diarrhea-predominant IBS, it is a significant concern for those with constipation-predominant symptoms. Management of dicyclomine-induced constipation often involves lifestyle modifications like increased fiber and fluids, but your healthcare provider should be involved in determining the best approach. Emerging and alternative medications that specifically target the mechanisms of IBS-C are available for those who find dicyclomine unsuitable. Always consult your doctor or pharmacist to discuss your symptoms, side effects, and all available treatment options.

For more detailed information on irritable bowel syndrome and its management, you can refer to resources from the National Institutes of Health(https://www.ncbi.nlm.nih.gov/books/NBK350058/).

Frequently Asked Questions

Dicyclomine is an anticholinergic drug that works by blocking the neurotransmitter acetylcholine, which normally signals intestinal muscles to contract. This blockage slows down gut motility, causing food and waste to move more slowly through the digestive tract, and can lead to constipation.

Constipation is a common side effect of dicyclomine, though the severity can vary among individuals. It's listed among other frequent anticholinergic side effects like dry mouth and blurred vision.

While typically mild, dicyclomine can cause severe constipation in some cases, especially at higher doses or if taken with other medications that have anticholinergic effects. This can potentially lead to more serious complications like bowel obstruction.

You can help manage constipation by increasing your fiber intake through fruits, vegetables, and whole grains, drinking more water, and getting regular exercise. Your doctor might also recommend an over-the-counter laxative, such as an osmotic laxative.

You should not stop taking dicyclomine without first speaking to your healthcare provider. Your doctor can help determine if the constipation is caused by the medication and if your dosage or medication needs to be changed.

No, dicyclomine is generally not recommended for individuals with constipation-predominant irritable bowel syndrome (IBS-C) because its constipating effect can worsen the condition. Other treatments are typically more appropriate.

Yes, alternative medications exist. For IBS-C, options like lubiprostone (Amitiza) and linaclotide (Linzess) are designed to increase intestinal fluid and aid bowel movements. Other therapies may also be available depending on your specific symptoms.

Yes, the risk and severity of constipation and other anticholinergic side effects tend to increase with higher dosages of dicyclomine. Your doctor may reduce your dosage if side effects are bothersome.