Laxatives are medications that help relieve constipation. There are several types of laxatives, and they work in different ways. For example, bulk-forming laxatives absorb water into the intestines and increase stool mass. Some examples include wheat dextrin (Benefiber®), psyllium (Metamucil®), or methylcellulose (Citrucel®).
Other laxatives soften stool by allowing water to more easily enter the stool. These include docusate sodium (Colace®).
In people with diarrhea-predominant IBS, over-the-counter antidiarrheal medicines may help. Examples include loperamide (Imodium®) or diphenoxylate with atropine (Lomotil®, Lonox®).
These medicines do not help with other IBS symptoms, like pain or constipation. In fact, in people with constipation, antidiarrheal medicines should be avoided.
Antidiarrheal drugs are usually recommended on an as-needed basis. If these medications are used incorrectly or for a long period of time, they may cause even worse problems.
Antidepressant medications have been shown to help with pain in people with IBS. They are especially helpful if a person has underlying depression or anxiety. Both of these conditions can make IBS symptoms worse.
Tricyclic antidepressants are one class of medicines that may be recommended. They include:
For treating IBS, the dosage of these medicines is usually much lower than that used to treat depression. It can take up to four weeks to see the benefit of these medicines. They may also help slow down movement through the intestines, which can be helpful for those people with diarrhea-predominant irritable bowel syndrome.
Another type of antidepressant, known as selective serotonin reuptake inhibitors (SSRIs for short), may be recommended. They work by increasing the level of serotonin available for cells of the brain. SSRIs include:
- Escitalopram (Lexapro®)
- Citalopram (Celexa®)
- Fluoxetine (Prozac®, Sarafem®, Selfemra™)
- Fluvoxamine (Luvox®, Luvox® CR)
- Paroxetine (Paxil®, Paxil CR®, Pexeva®, Brisdelle™)
- Sertraline (Zoloft®).
Other antidepressants that may be recommended include:
- Desvenlafaxine (Pristiq™)
- Duloxetine (Cymbalta®)
- Venlafaxine (Effexor®, Effexor XR®)
- Mirtazapine (Remeron®).
Benzodiazepine antianxiety medications may be recommended in people whose IBS symptoms are getting worse because of anxiety. Some examples include:
- Clidinium and chlordiazepoxide (Librax®), which contains both an antispasmodic and an antianxiety medication
- Clonazepam (Klonopin®)
- Alprazolam (Xanax®)
- Diazepam (Valium®)
- Lorazepam (Ativan®).
These medicines are generally not recommended for longer than two weeks because they can be addictive.