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 (such as Anaspaz, HyoMax)
  • Cimetropium
  • Dicyclomine (Bentyl)

Antidiarrheals

  • Loperamide (such as Imodium A-D)

Antidepressants

  • Amitriptyline (Elavil, Endep)
  • Paroxetine (Paxil)

Prokinetic Agents

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

5-hydroxytryptamine (5-HT) Antagonists and Agonists

  • Alosetron (Lotronex)

Anti-anxiety Medication

  • Diazepam (Valium)
  • Alprazolam (Xanax)
  • Lorazepam (Ativan)

Antibiotics

  • Rifaximin

Miscellaneous Medications

  • Lubiprostone
Over-the-Counter Medications

Fiber Supplements

Antidiarrheals

Antiflatulents

Probiotics

Pain Relievers

Prescription Medications
Antispasmodics

Common names include:

  • Hyoscyamine (such as Anaspaz, HyoMax)
  • Cimetropium
  • Dicyclomine (Bentyl)

These medicines may quiet the digestive system and reduce 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
  • Urinary retention
  • Visual problems
  • Sexual problems
  • Sleepiness
  • Confusion
  • Itching
  • Rash
Antidiarrheals

Common names include: loperamide (such as Imodium A-D)

These medicines are relatives of morphine but much less addicting.

Possible side effects include:

  • Dry mouth
  • Nausea and vomiting
  • Allergic reactions
  • Sleepiness
  • Confusion
  • Lightheadedness
  • Dizziness
  • Euphoria
  • Drowsiness
Antidepressants

Common names include:

  • Amitriptyline (Elavil, Endep)
  • Paroxetine (Paxil)

Depression is a common symptom in people with IBS. Some of these drugs may have antispasmodic effects.

Possible side effects include:

  • Dry mouth
  • Nausea
  • Dizziness
  • Sleep disruption
  • Diarrhea
  • Drowsiness
  • Anxiety
  • Weight loss or weight gain
  • Impaired sexual function
Prokinetic Agents

Common names include:

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

Cisapride, a drug used to increase bowel motility, has been removed from the US market. But, it may still be prescribed in special cases.

Possible side effects of domperidone and metoclopramide include:

  • Headache
  • Dry mouth
  • Stomach ache
  • Diarrhea
  • Restlessness
  • Sleep disruption
5-hydroxytryptamine (5-HT) Antagonists and Agonist

Common name includes: alosetron (Lotronex)

Alosetron may be prescribed to treat diarrhea, as well as general IBS symptoms, such as abdominal pain.

Possible side effects include:

  • Severe constipation
  • Nausea and vomiting
  • Stomach pain
Anti-Anxiety Medications

Common names include:

  • Diazepam (Valium)
  • Alprazolam (Xanax)
  • Lorazepam (Ativan)

These medicines may be prescribed to reduce anxiety associated with IBS.

Possible side effects include:

  • Drowsiness
  • Confusion
  • Impaired memory
  • Heart rate changes
  • Sleepiness
  • Constipation
  • Diarrhea
  • Rashes
  • Dry mouth
Antibiotics

Common names include: rifaximin

In some cases, antibiotics are recommended to treat IBS symptoms, such as bloating and diarrhea.

Miscellaneous Medications
  • Lubiprostone

Lubiprostone may be useful in managing IBS when constipation is the primary symptom and fiber is unsuccessful.

Possible side effects include:

  • Nausea and vomiting
  • Headache
  • Stomach ache
  • Heartburn
  • Diarrhea
Over-the-Counter Medications
Fiber Supplements

Common names include:

  • Psyllium
  • Bran
  • Polycarbophil
  • Methylcellulose

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 gas, which usually subside 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
  • Lomotil
  • Bismuth subsalicylate (Pepto-Bismol)

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

Antiflatulents

Common name includes: simethicone

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

Pain Relievers

Common names include: acetaminophen (Tylenol)

Acetaminophen may relieve abdominal pain.

When to Contact Your Doctor
  • If the medicine is not 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 schedule.
  • Know what side effects could occur. Report them to your doctor.
  • Talk to your doctor before you stop taking the medicine.
  • Plan ahead for refills if you need them.
  • Do not share your medicine with anyone.
  • Drugs can be dangerous when mixed. Talk to your doctor if you are taking more than one drug, including over-the-counter products and supplements.