The information provided here is meant to give you a general idea about each of the medicines listed below. Only the most general side effects are included, so ask your doctor if you need to take any special precautions. Use each of these medicines as recommended by your doctor, or according to the instructions provided. If you have further questions about usage or side effects, contact your doctor.

Since there is no known cause of IBS, medicines are used to treat specific symptoms. There are several types of medicines that are thought by some doctors to be helpful. But, not all of the medicines listed below are of proven value in treating symptoms of IBS. In some cases, your doctor may recommend that you take a combination of medicines.

Prescription Medications

Antispasmodics

  • Hyoscyamine (Anaspaz, A-Spas S/L, Cystospaz, Donnamar, ED-SPAZ, Gastrosed, Levbid, Levsin, Levsinex Timecaps, Levsin/SL, Symax SL)
  • Alverine citrate (Spasmonal)
  • Tincture of belladonna
  • Dicyclomine (Bentyl)

Antidiarrheals

  • Codeine
  • Loperamide
  • Lomotil

Antidepressants

  • Nortriptyline (Aventyl, Pamelor)
  • Desipramine (Norpramin)
  • Amitriptyline (Elavil, Endep)
  • Imipramine (Norfranil, Tipramine, Tofranil)
  • Fluoxetine (Prozac, Sarafem)
  • Paroxetine (Paxil)
  • Bupropion (Wellbutrin, Zyban)
  • Venlafaxine (Effexor)

Prokinetic Agents

  • Domperidone (Motilium)
  • Cisapride (Propulsid)
  • Metoclopramide (Reglan)

Serotonin Agents

  • Alosetron (Lotronex)
  • Tegaserod maleate (Zelnorm)

Anxiolytics

  • Diazepam (Valium)
  • Chlordiazepoxide (Librium)
  • Chlorazepate (Tranxene)
  • Alprazolam (Xanax)
  • Lorazepam (Ativan)
  • Oxazepam (Serax)

Antibiotics

  • Rifaximin

Miscellaneous Medications

  • Lubiprostone

Over-the-Counter Medications

Fiber Supplements

  • Psyllium (Alramucil, Effer-syllium, Fiberall, Konsyl, Metamucil, Modane Bulk, Mylanta Natural Fiber Supplement, Pro-Lax, Reguloid, Serutan, V-Lax)
  • Bran
  • Polycarbophil (Equalactin, Fibercon, Fiber-Lax, FiberNorm, Mitrolan)
  • Methylcellulose (Citrucel)

Antidiarrheals

  • Loperamide
  • Lomotil
  • Bismuth subsalicylate (Pepto-Bismol)

Antiflatulents

  • Simethicone (Flatulex, Gas Relief, Gas-X, Genasyme, Mylanta, Phazyme, Mylicon Drops)

Probiotics

Analgesics

  • Acetaminophen (eg, Tylenol)

Prescription Medications

Antispasmodics

Common names include:

  • Hyoscyamine (Anaspaz, A-Spas S/L, Cystospaz, Donnamar, ED-SPAZ, Gastrosed, Levbid, Levsin, Levsinex Timecaps, Levsin/SL, Symax SL)
  • Alverine citrate (Spasmonal)
  • Tincture of belladonna
  • Dicyclomine (Bentyl)

These medicines may quiet the digestive system and of relieve painful bowel spasms. When taken in reasonable doses, side effects are generally mild.

Possible side effects include:

  • Dry mouth
  • Nausea
  • Dizziness
  • Vomiting
  • Changes in heart rate
  • Palpitations
  • Urinary retention
  • Visual problems
  • Sexual problems
  • Sleepiness
  • Confusion
  • Itching
  • Rash
  • Allergic reactions

Antidiarrheals

Common names include:

These medicines are relatives of morphine but much less addicting.

Possible side effects include:

  • Dry mouth (from the atropine)
  • Nausea
  • Vomiting
  • Allergic reactions
  • Sleepiness
  • Confusion
  • Lightheadedness
  • Dizziness
  • Euphoria
  • Drowsiness

Antidepressants

Common names include:

All these agents are used to treat depression, a common symptom in people with IBS. Some of these agents (at the top of the list) also have antispasmodic effects and related side effects.

Possible side effects include:

  • Dry mouth
  • Nausea
  • Dizziness
  • Sleep disruption
  • Diarrhea (with fluoxetine and paroxetine)
  • Drowsiness
  • Anxiety
  • Impaired sexual function (Paxil, Prozac, Zoloft)

Prokinetic Agents

Common names include:

Cisapride is an agent used to increase bowel motility. It is available on a very limited, medically approved basis in the United States. While probably the only one of this group of medicines that is consistently effective, cisapride currently carries a warning about fatal heart rhythm disturbances primarily when used with certain other medicines. It should probably be used only with careful supervision by expert physicians specializing in treatment of IBS. Possible side effects include:

  • Fatal drug interactions
  • Headache
  • Diarrhea
  • Abdominal pain
  • Nausea
  • Constipation
  • Gas

Domperidone is an antinausea medicine (antiemetic) and also increases the movements and contractions of the stomach and bowel.

Possible side effects include:

  • Headache
  • Flushing
  • Sleepiness
  • Dry mouth
  • Breast swelling in males

Metoclopromide stimulates motility of the upper GI tract. Side effects include:

  • Restlessness
  • Anxiety
  • Drowsiness
  • Fatigue
  • Depression
  • Insomnia
  • Headache
  • Dizziness
  • Increased risk of tardive dyskinesia (a serious neurological condition) if taken more than 3 months

Serotonin Agents

Common names include:

Alosetron was re-approved by the FDA in June 2002 for women with severe IBS, unresponsive to other therapy, whose primary symptom is diarrhea. Alosetron can treat diarrhea, as well as general IBS symptoms, including abdominal pain.

The drug acts to block serotonin in the gastrointesinal tract and should be used with caution as it can cause severe side effects. Doctors can prescribe this drug under a risk management plan that requires special informed consent. Possible side effects include:

  • Severe constipation
  • Decreased blood flow to the colon , possibly leading to serious or fatal complications.

Tegaserod was approved by the FDA in July 2002 for short-term (about four weeks) use in women with IBS whose primary symptom is constipation. The drug acts to activate serotonin receptors in the gastrointestinal tract, thus increasing the movement of stools through the bowels. A possible side effect is diarrhea. However, in March 2007, the FDA withdrew tegaserod from the market due to a slightly increased risk of heart attack, angina, and stroke in patients taking the medicine.

Another medicine called cilansetron has not been approved yet by the FDA. Cilansetron is for men and women whose main IBS symptom is diarrhea. The medicine can treat diarrhea and general symptoms of IBS.

Anxiolytics

Common names include:

Used as a mild sedative for the emotional upset associated with IBS, these agents can be habit-forming. Possible side effects include:

  • Drowsiness
  • Confusion
  • Impaired memory
  • Heart rate changes
  • Sleepiness
  • Constipation/diarrhea
  • Rashes
  • Dry mouth

Antibiotics

While the benefits of rifaximin in IBS remain incompletely established, some data suggests that IBS may not infrequently be caused by “overgrowth” of normal bacteria within the bowel. As a result, medicines that can kill these bacteria (without promoting the growth of disease-causing organisms) have been tried as treatment for IBS. Several studies suggest that rifaximin (a medicine that is not absorbed into the system but remains within the bowel) can reduce at least the symptoms of bloating. There seem to be few if any serious side effects, and some physicians also use this drug when diarrhea is a major symptoms of IBS.

Miscellaneous Medications

Lubiprostone is one of a number of newer medicines that may be effective in IBS. Lubiprostone affects the transfer of chloride across the bowel wall and may be useful in managing IBS when constipation is the primary symptoms and fiber is unsuccessful. Lubiprostone may be safer than alternative medicines, but it is too early to fully judge its effectiveness and safety.

Over-the-Counter Medications

Fiber Supplements

Common brand names:

  • Psyllium (Alramucil, Effer-syllium, Fiberall, Konsyl, Metamucil, Modane Bulk, Mylanta Natural Fiber Supplement, Pro-Lax, Reguloid, Serutan, V-Lax)
  • Bran
  • Polycarbophil (Equalactin, Fibercon, Fiber-Lax, FiberNorm, Mitrolan)
  • Methylcellulose (Citrucel)

Dietary fiber is the undigestible part of plants considered important in the optimal functioning of the digestive tract. Initially, fiber supplements may cause bloating and flatulence (gas), which usually subsides within a few weeks. Increase your fiber intake gradually. Drink plenty of water as you increase your fiber to promote regularity. Bran may be less effective than psyllium or other “soluble” fibers.

Possible side effects include:

  • Bloating
  • Flatulence

Antidiarrheals

Common names include:

  • Loperamide
  • Lotomil
  • Bismuth subsalicylate (Pepto-Bismol)

Loperamide can cause constipation. Bismuth subsalicylate soothes the digestive tract without producing constipation.

Antiflatulents

  • Simethicone (Flatulex, Gas Relief, Gas-X, Genasyme, Mylanta, Phazyme, Mylicon Drops)

This agent breaks up bubbles in the stomach to make it easier for gas to exit upward, before it gets into the intestines.

Probiotics

Probiotics are "friendly" bacteria like acidophilus, which is found in yogurt. Probiotics may help improve abdominal pain and other symptoms of IBS. This bacteria can also be bought as supplements. Talk to your doctor if you are interested in adding probiotics to your diet.

Analgesics

Findings from a recent clinical trial showed modest benefit of acetaminophen for treatment of crampy abdominal pain in 2000 patients with IBS.

When to Contact Your Doctor

  • If the current treatment isn't working
  • If you are getting worse
  • If you are having new symptoms

Special Considerations

If you are taking medicines, follow these general guidelines:

  • Take your medicine as directed. Do not change the amount or the schedule.
  • Do not stop taking them without talking to your doctor.
  • Do not share them.
  • Use a measuring spoon, cup, or syringe to give the right dose. Make sure it has the same measurements as the medicine. For example, if the medicine is given in milligrams (mg), the device should also say mg.
  • Know what the results and side effects. Report them to your doctor.
  • Some drugs can be dangerous when mixed. Talk to a doctor or pharmacist if you are taking more than one drug. This includes over-the-counter medicine and herb or dietary supplements.
  • Plan ahead for refills so you don’t run out.