These drugs stop painful spasms by targeting smooth muscles in the digestive tract and are particularly effective in people living with diarrhea-predominant IBS (IBS-D).
This article looks at types of antispasmodics used for IBS, their benefits and side effects, and other ways to treat IBS.
Why Antispasmodics Are Used for IBS
Studies suggest about 5% of Americans have IBS symptoms. Researchers have yet to identify the cause of IBS, so treatment is primarily aimed at relieving the symptoms, which can include:
Abdominal painCrampingBloatingDiarrheaConstipation
Some antispasmodics (also referred to as spasmolytics) have proven moderately effective in alleviating symptoms by targeting and relaxing the smooth muscles of the digestive tract, preventing spasms.
Because symptoms of IBS tend to be worse after eating, taking these medications 30 to 60 minutes before a meal may help prevent symptoms.
Types of Antispasmodics for IBS
There are two types of antispasmodic medications used for IBS: anticholinergics and direct smooth muscle relaxants. Peppermint oil also has antispasmodic properties and is sometimes used.
Anticholinergics
Anticholinergics are a type of antispasmodic designed to block the neurotransmitter acetylcholine. This is a chemical produced by the body that acts on the autonomic nervous system, the part of the nervous system associated with involuntary functions.
Anticholinergics stop cell signals that contract muscles in the digestive tract, heart, lungs, and urinary tract. In addition to IBS, they’re used for conditions including pancreatitis, asthma, chronic obstructive pulmonary disorder (COPD), and Parkinson’s disease.
By blocking acetylcholine receptors in the digestive tract, anticholinergics can slow digestion, decrease the severity of muscle spasms, and reduce the overproduction of mucus.
Examples of commonly prescribed anticholinergics include:
Bentyl (dicyclomine) Buscopan (hyoscine butylbromide) Levsin (hyoscyamine)
Anticholinergics can affect organ systems beyond the digestive tract, triggering side effects such as:
Blurred or double vision Confusion, concentration, and memory problems Constipation Decreased urination Dizziness Dry mouth Gastric reflux High body temperature Increased heart rate Lack of sweating, which can lead to heat exhaustion Poor coordination Sore throat
Due to the risk of constipation, these antispasmodics are best used in cases of diarrhea-predominant IBS (IBS-D) rather than constipation-predominant IBS (IBS-C).
Direct Smooth Muscle Relaxants
A class of drugs called direct smooth muscle relaxants, which are synthetic anticholinergics, appear to be more effective at treating IBS than regular anticholinergics. These drugs also have fewer problems with side effects.
However, these antispasmodics aren’t currently FDA-approved for any use in the United States. Medications available in other countries include:
CimetropiumMebeverineOtiloniumPinaverium bromideTrimebutine
These drugs work by altering the transportation of sodium and calcium. Direct smooth muscle relaxants affect the smooth muscle of the digestive tract only. They’re only used for IBS and intestinal cramping.
Direct smooth muscle relaxants very rarely have reports of side effects. When they are reported, common ones appear to be:
Dry mouth Nausea Dizziness Indigestion Heartburn Constipation Insomnia (trouble sleeping) Anorexia (loss of appetite or avoiding food) Headache Fatigue Unusual muscle movements Skin rash or itchy skin
You shouldn’t take this type of antispasmodic if you have paralytic ileus, a nerve condition that affects digestion.
Direct smooth muscle relaxants should be used with caution in:
Young children People with angioedema (swelling) People with thrombocytopenia (low blood platelet levels)
Peppermint Oil
Peppermint oil is an over-the-counter (OTC) natural antispasmodic. It contains menthol, a substance that scientists believe relaxes smooth muscle by operating on calcium channels in smooth muscle cells in the gut.
Some prescription calcium channel blockers are used similarly to treat high blood pressure (hypertension) and other cardiovascular disorders, because they relax smooth muscles in the blood vessels.
Peppermint oil is used for IBS, other digestive problems, and to treat sinus infections and headaches.Most of the research into the medicinal uses of peppermint oil has been related to IBS.
A 2014 review of studies by researchers at the University of California, San Diego concluded that persons with IBS symptoms were nearly three times more likely to achieve relief with peppermint oil than with a placebo.
While considered safe for short-term use, peppermint oil is known to cause heartburn in some people. To avoid this side effect, you can use enteric-coated capsules. Their coating doesn’t dissolve until it’s farther along in the digestive system, which prevents irritation.
This natural antispasmodic should be used with caution if you have:
HeartburnHiatal herniaSevere liver damageGallbladder inflammationBile duct obstruction
Be sure to consult your healthcare provider before taking peppermint oil or any other OTC supplement.
Who Should Not Take Antispasmodics
Certain people should avoid antispasmodic drugs. You shouldn’t take anticholinergics if you’re older than 65, pregnant or breastfeeding, or if you have:
Myasthenia gravis, an autoimmune disorder that affects muscles Hyperthyroidism (excessively high thyroid function) Glaucoma Prostate conditions, including hyperplasia (enlargement) and hypertrophy High blood pressure Urinary tract blockage Severe ulcerative colitis Stenosing peptic ulcer, which causes narrowing at the affected site Paralytic ileus Intestinal obstruction Toxic megacolon Heart disease Liver or kidney disease
Other Ways to Treat IBS
In addition to antispasmodic medications, dietary changes can also significantly improve IBS symptoms. Depending on the symptoms you’re experiencing, you may want to:
Increase dietary fiber or use a fiber supplement to relieve IBS constipation or diarrhea. Increase water intake if constipated. Avoid caffeine (peppermint tea is an excellent substitute). Avoid legumes to decrease bloating.
Limiting foods that contain lactose, fructose, or FODMAPs (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols) may offer benefits when managing IBS symptoms.
Summary
Treatments for irritable bowel syndrome (IBS) may include antispasmodic drugs that work to prevent spasms in the smooth muscle of your digestive tract. Reducing the spasms can improve symptoms including abdominal pain and bloating, especially in people with diarrhea related to IBS-D.
Anticholinergics and direct smooth muscle relaxants, along with peppermint oil, may offer benefits. It’s important to note, however, that these medications may have side effects. People with certain health conditions may need to use other therapies.
Be sure to discuss IBS medications with your healthcare provider and closely follow their recommendation for treating your condition.
