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Antispasmodics

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By Editorial Team

3 min read

Reviewed by: HU Medical Review Board | Last reviewed: July 2024 | Last updated: August 2024

Irritable bowel syndrome (IBS) can cause a number of symptoms related to the gut. Belly pain is a common symptom many people with IBS face. Having belly pain at least once a week over the past 3 months is 1 of the requirements for an IBS diagnosis. Antispasmodics are a class of drugs used to treat belly pain.1,2

How do antispasmodics work?

When the muscles in the gut wall spasm, or uncontrollably contract, this can cause:1,2

Antispasmodics for IBS act by reducing these muscle spasms. They are usually given to people who have IBS with diarrhea (IBS-D). Sometimes, they may be given to people who have IBS with constipation (IBS-C). They may also be given to people who have IBS with mixed diarrhea and constipation (IBS-M).1,2

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Most antispasmodics for IBS used in the United States (US) are anticholinergic agents. These drugs work by blocking acetylcholine. This is a chemical that sends messages between the brain and the rest of the body. It is active in the function of:1-3

  • Gut organs
  • The heart
  • Blood vessels
  • Airways
  • Urinary organs

The antispasmodics below have been approved by the US Food and Drug Administration (FDA):2,4,5

  • Dicyclomine
  • Chlordiazepoxide and clidinium

Hyoscyamine is another antispasmodic available in the US. But it has not been approved by the FDA.6

These drugs can be found under many different brand names.4-6

What are the possible side effects of antispasmodics?

Side effects can vary based on the specific antispasmodic you are taking. Some of the side effects are:2,4-6

  • Blurry vision
  • Dizziness
  • Dry mouth
  • Nausea
  • Weakness
  • Drowsiness
  • Nervousness

Other side effects that people have reported are:2,4-6

  • Trouble urinating
  • Abnormal or fast heartbeat
  • Sensitivity to light
  • Loss of taste
  • Headaches
  • Trouble sleeping
  • Constipation
  • Bloating
  • Seeing things that are not there (hallucinations)

Librax® (chlordiazepoxide and clidinium) contains 2 active ingredients. Clidinium is an antispasmodic agent that can help with belly pain. Chlordiazepoxide is a benzodiazepine (BZD) that can relieve anxiety. BZDs have other risks and side effects associated with them.5

Librax should not be used long term. BZDs can be addicting. Misuse of such drugs can lead to overdose or death. Use of BZDs with opioids can lead to severe problems, such as:5

  • Sedation (sleep caused by drugs)
  • Coma
  • Dangerously low breathing
  • Death

These are not all the possible side effects of antispasmodics. Talk to your doctor about what to expect when taking these drugs. You should also call your doctor if you have any changes that concern you when taking these drugs.

Who is more likely to experience side effects from antispasmodics?

Having certain conditions can put you at higher risk for side effects. You should tell your doctor if you have or have ever had:4-6

  • Glaucoma or other eye problems
  • Problems urinating or emptying the bladder (including having an enlarged prostate)
  • Problems with your kidneys, heart, or liver
  • Bleeding disorders
  • Myasthenia gravis
  • Any condition that blocks your gut
  • Ulcerative colitis
  • Heartburn or acid reflux
  • Mental illness or depression
  • A history of drug or alcohol abuse or addiction

Alternative antispasmodics for IBS

Peppermint oil also has similar effects as antispasmodics. Research shows that peppermint oil can help with symptoms of IBS, such as belly pain. Peppermint oil is available over the counter. Talk to your doctor before taking peppermint oil supplements.1,2

Other things to know

Before starting treatment for IBS, tell your doctor about all your health conditions and any other drugs, vitamins, or supplements you take. This includes over-the-counter drugs.

Most people with IBS try many treatment options before finding the right treatment combination that works for their symptoms. On top of taking antispasmodics, you can try:1

  • Drugs to treat diarrhea
  • Adding fiber or probiotics to your diet
  • Making other changes to your diet
  • Managing stress
  • Therapy
  • Alternative and complementary methods