Discover Bentyl tablet information including uses, side effects. Leave reviews and learn how it affects your stomach pain in irritable bowel syndrome.

There's no doubt that for many people, this medication works really well and can be used in the long term if necessary (in the UK it is marketed under the name Merbentyl).

So let's look at it's how it works, the doses and much more...

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What is Bentyl?

This medications generic name is Dicyclomine, an antispasmodic drug which eases abdominal pain in irritable bowel syndrome. It is classed as an antimuscarinic drug as it has an effect on the neurotransmitter called acetylcholine, a chemical messenger that attaches to the acetylcholine receptor. These receptors are found on the membranes of nerve cells, preventing smooth muscle contraction in the GI tract as well as in other parts of the body including the cardiovascular system, urinary system and in the lungs as well.

What is it used for?

It's uses include:

  • Improving gut spasms and stomach pain in the irritable bowel syndrome
  • Reduces gastric acid secretions
  • Treating bed wetting/urine incontinence - unlicensed use

What is the correct dose?

The adult dose depends on the preparation being used:


The dose is 20mg four times a day. This dose can be increased to 40mg four times a day if necessary, although side effects may limit this higher dose.

Bentyl tablets are 20 mg each

Discontinue if no response after 2 weeks

Other Preparations

The other preparations are:


The dose is the same as the tablets at 20mg four times a day, increasing to 40 mg four times a day if necessary.

Capsules are 10 mg each


Comes as 10mg/5ml. The dose is 20mg or 2 x 5ml spoonfuls four times a day.

Intramuscular injection (IM)

The dose of intramuscular injection is 10-20mg four times a day, but should only be used by a health professional when you are unable to take Bentyl tablets and should be limited to 24-48 hours. 

Medication side effects

  • Constipation
  • Palpitations including slow heart beat (bradycardia) then fast heart beat (tachycardia) and other heart rhythm disorders
  • Reduced lung (bronchial) secretions
  • Urinary urgency, retention and difficulty passing urine
  • Dilated pupils in your eyes with blurring of vision
  • Eye sensitivity to sunlight (photophobia)
  • Dry mouth 
  • Flushing
  • Nausea
  • Vomiting
  • Giddiness
  • Dry skin
  • Occassional confusion - particularly in the elderly

Are there any contraindications to taking this medication?

Contraindications to taking this medication include:

  • Allergy to the medication
  • Myasthenia gravis - only to be used under specialist supervision
  • Glaucoma
  • Bowel obstruction
  • Urinary obstruction
  • Severe ulcerative colitis


Cautious use of this drug in:

  • Heart conditions - particularly in heart rhythm disturbances
  • The elderly
  • Parkinson's disease
  • Anyone with heart or kidney disease

Drug interactions

  • Glaucoma treatments - Bentyl may antagonise their effects
  • Other anticholinergic/muscarinic antagonists - may potentiate the effects eg benzodiazepines such as diazepam, Amitriptyline, some antihistamines, some anti-psychotic drugs eg phenothiazines, narcotic analgesics eg morphine, diamorphine, buprenorphine, codeine
  • Anti-sickness medicines - metoclopramide and domperidone: may reduce effectiveness, cyclizine - increased drowsiness
  • Antacids - may prevent absorption of the drug

Is it safe in pregnancy?

It is thought to be safe to take in pregnancy if necessary. There are no specific clinical trials in pregnancy, but the drug has been used in pregnant women as appears safe under physician guidance.

Is it safe to breastfeed?

This drug passes into human breast milk and is therefore contraindicated in breast feeding mothers.

Doctors view

Bentyl tablets (or Dicyclomine) is an excellent drug in some people with IBS. It is particularly helpful in gut spasms, but should be used with caution in some people as described before. For short term use, particularly if there is any anxiety, this drug can be very effective. 

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