Does Bentyl (dicyclomine) cause side effects?

Bentyl (dicyclomine) is an anticholinergic used to treat irritable bowel syndrome (IBS). Anticholinergic drugs block the effects of acetylcholine, the chemical transmitter that nerves release in order to cause muscles to contract.

They prevent contraction of muscles by blocking the acetylcholine receptors on the muscle cells. Anticholinergic drugs also have a direct relaxing effect on muscle. Bentyl is used to reduce contraction of the muscles in the intestines

Common side effects of Bentyl include

Serious side effects of Bentyl include

Drug interactions of Bentyl include amantadine, antiarrhythmics, antihistamines, antipsychotics, benzodiazepines, MAO inhibitors, narcotics, nitrates and nitrites, sympathomimetic agents, tricyclic antidepressants, and other drugs having anticholinergic activity may increase certain actions or side effects of anticholinergic drugs including Bentyl.

  • Anticholinergics antagonize the effects of antiglaucoma agents and may increase intraocular pressure.
  • Anticholinergic drugs in the presence of increased intraocular pressure may be hazardous when taken concurrently with agents such as corticosteroids.
  • Use of Bentyl in patients with glaucoma is not recommended.
  • Interaction with other gastrointestinal motility drugs may antagonize the effects of drugs that alter gastrointestinal motility, such as metoclopramide.
  • Because antacids may interfere with the absorption of anticholinergic agents including Bentyl, simultaneous use of these drugs should be avoided.
  • Anticholinergic agents may affect gastrointestinal absorption of various drugs by affecting gastrointestinal motility, such as slowly dissolving dosage forms of digoxin; increased serum digoxin concentration may result.
  • The inhibiting effects of anticholinergic drugs on gastric hydrochloric acid secretion are antagonized by agents used to treat achlorhydria and those used to test gastric secretion.

There are no adequate studies of the effect of Bentyl in pregnant women at recommended doses.

Bentyl is excreted into breast milk. Since there have been reports of apnea (cessation of breathing) when Bentyl has been given to children, it should not be used by breastfeeding mothers.

What are the important side effects of Bentyl (dicyclomine)?

Common side effects include:

Other important side effects include:

Bentyl (dicyclomine) side effects list for healthcare professionals

The pattern of adverse effects seen with dicyclomine is mostly related to its pharmacological actions at muscarinic receptors. They are a consequence of the inhibitory effect on muscarinic receptors within the autonomic nervous system. These effects are dose-related and are usually reversible when treatment is discontinued.

The most serious adverse reactions reported with dicyclomine hydrochloride include cardiovascular and central nervous system symptoms.

Clinical Trials Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.

The data described below reflect exposure in controlled clinical trials involving over 100 patients treated for functional bowel/irritable bowel syndrome with dicyclomine hydrochloride at initial doses of 160 mg daily (40 mg four times a day)

In these trials most of the side effects were typically anticholinergic in nature and were reported by 61% of the patients. Table 1 presents adverse reactions (MedDRA 13.0 preferred terms) by decreasing order of frequency in a side-by-side comparison with placebo.

Table 1: Adverse reactions experienced in controlled clinical trials with decreasing order of frequency

MedDRA Preferred Term Dicyclomine Hydrochloride (40 mg four times a day) % Placebo %
Dry Mouth 33 5
Dizziness 40 5
Vision blurred 27 2
Nausea 14 6
Somnolence 9 1
Asthenia 7 1
Nervousness 6 2

Nine percent (9%) of patients were discontinued from Bentyl because of one or more of these side effects (compared with 2% in the placebo group). In 41% of the patients with side effects, side effects disappeared or were tolerated at the 160 mg daily dose without reduction. A dose reduction from 160 mg daily to an average daily dose of 90 mg was required in 46% of the patients with side effects who then continued to experience a favorable clinical response; their side effects either disappeared or were tolerated.

Postmarketing Experience

The following adverse reactions, presented by system organ class in alphabetical order, have been identified during post approval use of Bentyl. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.

Cases of thrombosis, thrombophlebitis and injection site reactions such as local pain, edema, skin color change and even reflex sympathetic dystrophy syndrome have been reported following inadverent IV injection of Bentyl.

Adverse Reactions Reported With Similar Drugs With Anticholinergic/Antispasmodic Action

What drugs interact with Bentyl (dicyclomine)?

Antiglaucoma Agents

  • Anticholinergics antagonize the effects of antiglaucoma agents. Anticholinergic drugs in the presence of increased intraocular pressure may be hazardous when taken concurrently with agents such as corticosteroids.
  • Use of Bentyl in patients with glaucoma is not recommended.

Other Drugs With Anticholinergic Activity

Other Gastrointestinal Motility Drugs

  • Interaction with other gastrointestinal motility drugs may antagonize the effects of drugs that alter gastrointestinal motility, such as metoclopramide.

Effect Of Antacids

  • Because antacids may interfere with the absorption of anticholinergic agents including Bentyl, simultaneous use of these drugs should be avoided.

Effect On Absorption Of Other Drugs

  • Anticholinergic agents may affect gastrointestinal absorption of various drugs by affecting gastrointestinal motility, such as slowly dissolving dosage forms of digoxin; increased serum digoxin concentration may result.

Effect On Gastric Acid Secretion

  • The inhibiting effects of anticholinergic drugs on gastric hydrochloric acid secretion are antagonized by agents used to treat achlorhydria and those used to test gastric secretion.

Treatment & Diagnosis

Medications & Supplements

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Medically Reviewed on 12/17/2020
References
FDA Prescribing Information

Some sections provided courtesy of the U.S. Food and Drug Administration (FDA) prescribing information