Chronic Functional Constipation and IBS-C Medications

Treatments increase fluid in the intestines and stimulate bowel movements

Most of the medications for constipation-predominant irritable bowel syndrome (IBS-C) are also used for chronic functional constipation, though there are some differences in how they're used. In both cases, though, these constipation medications are generally only started after dietary and behavioral changes have failed.

If that occurs, over-the-counter (OTC) laxatives may provide some relief. Persistent cases may require a prescription constipation medication that increases fluid in the intestines and stimulates bowel movements.

This article lists various CIC and IBS-C medications, details who they are appropriate for, and discusses how each of them work to get things moving again.

Doctor with patient
John Fedele / Blend Images / Getty Images 

OTC Constipation Medications

OTC remedies work well for many people with constipation due to CIC or IBS-C. These have the advantage of being readily available at drugstores without a prescription.

Bulk-Forming Laxatives

Fiber products like psyllium (Konsyl, Metamucil, Perdiem) are not absorbed by the intestines and therefore "bulk up" the stool. Other bulk-forming laxatives include:

  • Citrucel (methylcellulose)
  • FiberCon, Fiber-Lax, Mitrolan (calcium polycarbophil)
  • Benefiber (wheat dextrin)

In its 2021 clinical guidelines for IBS, the American College of Gastroenterology (ACG) recommends soluble fiber for IBS, but not insoluble fiber. Soluble fiber is found in psyllium, oat bran, barley, and beans. Insoluble fiber is found in wheat bran, whole grains, and some vegetables.

Psyllium has the added advantage of not fermenting well in the gut, because foods that ferment in the colon can lead to extra gas and liquid, potentially making symptoms worse for people with IBS-C.

Therefore, any of the above bulk-forming laxatives may help with constipation, but you may get the best results from psyllium (also known as ispaghula) if you have IBS-C.

Osmotic Laxatives

Osmotic laxatives draw fluid into the intestines by osmosis. The increase in intestinal water softens and bulks the stool, normalizing the consistency. There are a few common types of osmotic laxatives.

Miralax (polyethylene glycol, a.k.a. PEG) is a laxative powder that your healthcare provider may recommend to ease your constipation. Miralax draws water into the stool, softening it and inducing the urge for a bowel movement.

The ACG's 2021 IBS guidelines advise against the use of PEG alone for the treatment of constipation present in IBS-C, stating that it does not appear to help with abdominal pain symptoms. Even so, they acknowledge that it can be a helpful and inexpensive first-line constipation medication, with a long safety record.

Sorbitol is a sugar alcohol known as a polyol. Although it may be helpful for some people for constipation, it should be noted that it can cause bloating and gas in some people and is not recommended for people with IBS who are trying to follow a low-FODMAP diet.

Saline laxatives like magnesium hydroxide (Milk of Magnesia), magnesium citrate (Evac-Q-Mag) and sodium phosphate have long histories as constipation medications. Saline laxatives can cause problems in the balance between water and electrolytes in the body if used more than directed.

Some people have had life-threatening kidney failure and have even died after taking more than the recommended dose of OSP.

Stimulant Laxatives

Stimulant laxatives work by causing the walls of the intestine to contract, which pushes the stool along.

They can cause cramping and there is concern that long-term use may cause damage to the intestinal wall, both of which are reasons they may not be a good option as an IBS-C medication for people already experiencing abdominal pain.

Examples of stimulant laxatives include:

  • Senna (Ex-Lax, Senokot)
  • Bisacodyl (Correctol, Dulcolax)

Lubricant/Emolient Laxatives

Some people take mineral oil internally as a laxative, because it lubricates the walls of the intestines. Healthcare providers advise that there are safer remedies to try, and that long-term use of mineral oil may lead to nutritional deficiencies, plus other problems such as leaking mineral oil out of your anus.

Your healthcare provider will likely recommend that you continue any dietary and lifestyle changes recommended to you before you started medication. These include increasing dietary fiber and water, listening to your body's cues to defecate, and increasing physical activity 

Prescription Functional Constipation and IBS-C Medications

If OTC remedies are ineffective, you may need a prescription CIC or IBS-C medication. See your provider about whether one of the medications below might be a good fit for your symptoms.

Prescription Osmotic Laxatives

Lactulose operates like the other osmotic laxatives above, but it is available only by prescription. Brand names include Cephulac, Chronulac, Constilac, Cholac, Constulose, Duphalac, Enulose, Generlac, and Kristalose. 

Lactulose is a man-made disaccharide (a kind of sugar) that is broken down by bacteria in the colon. Because its action doesn't begin until it reaches the colon, it can take 24 to 48 hours to lead to a bowel movement.

Lactulose is generally recommended for short-term use. It can cause bloating and gas, so it may not be a good option as an IBS-C medication or for people on a low-FODMAP diet.

Chloride Channel Activators

Amitiza (lubiprostone) is a prescription medication approved by the Food and Drug Administration (FDA) for the treatment of IBS-C and functional constipation. It is a pill that should be taken with food, in part to diminish the side effect of nausea. It increases the volume of fluid in the intestines and also increases gut movement (peristalsis), which eases the passage of stool.

Lubiprostone is FDA-approved for the treatment of adults with functional constipation, and also for women with IBS-C. Its safety has not been evaluated for men with IBS-C.

The ACG guidelines recommend its use as an IBS-C medication, and they note that some women respond to the drug better over time. You should not take Amitiza if you have a bowel obstruction or experience severe diarrhea. Safety of use during pregnancy or breastfeeding is uncertain.

Guanylate Cyclase Activators

These drugs also act to increase intestinal fluid and intestinal movement by targeting receptors called guanylate cyclase-C (GC-C) receptors. Both of these medications are approved by the FDA for the treatment of functional constipation and IBS-C, and both are also recommended for IBS-C in the current ACG guidelines:

Trulance (plecanatide) is approved for adults. Because of the risk of diarrhea from the medication, use in children can lead to severe dehydration and is not recommended. Plecanatide can be taken with or without food.

Linzess (linaclotide) should also only be used in adults. It is taken on an empty stomach, at least 30 minutes before the first meal of the day.

5-HT4 Receptor Agonists

Selective serotonin type 4 (5-HT4) receptor agonists act on the receptor sites for the neurotransmitter serotonin in the gastrointestinal (GI) system. This helps to accelerate transit of the stool through the bowel and works well as a constipation medication.

Motegrity (prucalopride) was approved by the FDA in 2018 for functional constipation (chronic idiopathic constipation) in adults. Prucalopride shouldn't be used by people with bowel obstructions or inflammatory bowel disease.

Zelnorm (tegaserod) is approved for adult women with IBS-C who are under 65 years of age and are at low risk for a heart attack. Women with more than one of these risk factors shouldn't take tegaserod:

  • Being over 55 years old
  • Being a current smoker
  • Having hypertension or having a treatment history for hypertension
  • Having hyperlipidemia or a history of treatment for hyperlipidemia
  • Having diabetes or a history of diabetes
  • Being obese (defined as a BMI > 30)

Zelnorm's safety has not been evaluated in men.

Certain people are never supposed to take tegaserod, including people who have ever had a heart attack, a stroke, angina, any kind of intestinal ischemia, and people whose liver or kidneys don't work well. In addition, you should not take tegaserod if you have a history of bowel obstruction, active gallbladder disease, or suspected dysfunction with your sphincter of Oddi.

In 2002, Zelnorm was voluntarily withdrawn from the United States market over concerns about increased cardiac events. Zelnorm was reintroduced to the United States Market in March 2019.

The ACG recommends use of Zelnorm as an IBS-C medication for women with a low risk of cardiac or ischemic bowel events, but only if other approved medications above have not been successful.


Antidepressants are not formally approved as a treatment for chronic idiopathic constipation or IBS-C. However, they are sometimes prescribed in the treatment of IBS. Antidepressants work as IBS-C medications because they alter intestinal muscle movement and pain, due to their interaction with neurotransmitters in the digestive system.

The main antidepressant classes used in this way are selective serotonin reuptake inhibitors (SSRIs) and tricyclic antidepressants. SSRIs include Prozac (fluoxetine) and Zoloft (sertraline). Tricyclic antidepressants (TCAs) include Elavil (amitriptyline), Pamelor (nortriptylene), Tofranil (imipramine), and Norpramin (despiramine).

The ACG recommends TCAs for IBS patients because they have multiple mechanisms by which they work on IBS-related abdominal pain. They recommend starting at a low dose and then working up until relief is achieved.

Some clinicians recommend SSRIs more often for constipation and TCAs for diarrhea.


Antispasmodics are muscle relaxants. Bentyl (dicyclomine) and Levsin (hyoscyamine) are antispasmodics sometimes used for the treatment of IBS-C. The 2021 ACG guidelines recommend against these antispasmodic medications, stating that there is no quality evidence that they actually work.

Frequently Asked Questions

  • What constipation medications are safe while breastfeeding?

    Most OTC laxatives are safe to use during pregnancy and breastfeeding, but you should talk to your doctor before using. With the exception of lactulose, prescriptions IBS-C medications are not approved for use during pregnancy. Zelnorm (tegaserod) and Motegrity (prucalopride) are excreted through breast milk and should not be used by nursing mothers.

  • Which probiotic is best for IBS-C?

    In general, probiotics have shown to be helpful for constipation and other symptoms of IBS-C. Probiotic strains found to be somewhat effective for IBS-C include: 

    • Bifidobacterium infantis
    • Bifidobacteriumlactis
    • A blend including Bifidobacterium lactis, Streptococcus thermophilusLactobacillus bulgaricus 
    • A blend of Lactobacillus rhamnosus, L. plantarum, L. acidophilus, and Enterococcus faecium

  • What helps IBS-C pain?

    Aside from constipation medications and some antidepressants, IBS-C pain may be relived by applying heat to the abdomen, gentle exercise, massaging the midsection in a clockwise motion, and sipping herbal tea, such as peppermint, licorice, ginger, fennel, or lavender.

  • How do you know if you have IBS-C?

    IBS-C symptoms include abdominal pain and discomfort, bloating, chronic constipation, and gas. If you suspect you have IBS-C, talk to your healthcare provider about testing and treatment.

  • Can dietary changes improve IBS-C?

    Dietary changes are commonly the first line of treatment for IBS-C. The general advice is to eat more fiber, avoid gluten, or follow a low-FODMAP diet.

15 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Barbara Bolen, PhD
Barbara Bolen, PhD, is a licensed clinical psychologist and health coach. She has written multiple books focused on living with irritable bowel syndrome.