Irritable Bowel Syndrome Diagnosis and Treatment

By Jillian Foglesong Stabile, MD

February 13, 2024

IBS 2024

Irritable bowel syndrome (IBS) is an extremely common condition that causes abdominal pain. While it can be painful and inconvenient, IBS doesn’t cause an increased risk of conditions such as colon cancer. There are ways to manage IBS symptoms to improve your quality of life.

What are the symptoms of irritable bowel syndrome?

Irritable bowel syndrome has many possible symptoms, and not everyone with this condition has all of the symptoms. In addition, the symptoms may not be present all the time. Symptoms include:

  • Abdominal pain, usually crampy
  • Gas and bloating
  • Diarrhea, constipation, or alternating between the two
  • Mucus in your stool
  • Sensation of incomplete bowel emptying
  • Changes in bowel movement frequency
  • Changes in how your bowel movements look
  • The feeling that you urgently need to have a bowel movement

Symptoms such as vomiting, persistent pain, bleeding, anemia, or weight loss are not normal with irritable bowel syndrome. These are considered “red flags” or symptoms that should prompt you to seek medical evaluation for other possible causes of your symptoms. It is very important to tell your healthcare provider if you are experiencing red flag symptoms or changes to your normal because patients with irritable bowel syndrome are less likely to seek care for these abnormal findings because they are accustomed to having bowel problems.

What causes irritable bowel syndrome?

The exact cause of irritable bowel syndrome is not well understood, but it is believed to be related to the nerves in the wall of the gastrointestinal tract. Nerves originate in the brain and travel through the spinal cord to the gut. They help control the movement and functions of the bowels. Some of the symptoms of irritable bowel syndrome may be the result of food moving through the gut too quickly or too slowly due to muscle contractions in the gut.

Irritable bowel syndrome may also be triggered by increased stress, severe infections of the GI tract, changes in the gut bacteria, or overgrowth of bacteria in the gut. The gut has a normal microbiome, which can vary due to several factors. Changes in this microbiome can cause changes in your bowel movements. Stress in early childhood may increase the risk of irritable bowel syndrome.

Who gets irritable bowel syndrome?

There are several potential risk factors for irritable bowel syndrome. Irritable bowel syndrome is more common in women than men. People with anxiety and depression are also more likely to get irritable bowel syndrome as are people with a family history of the condition. Symptoms of the condition usually start before the age of 50. Irritable bowel syndrome symptoms may worsen in response to certain foods or stress, so people with sensitivity to foods or who have high-stress lifestyles may be more likely to develop irritable bowel syndrome.

What are the complications of irritable bowel syndrome?

There are a few possible complications associated with irritable bowel syndrome:

  • Malnourishment can occur as a result of avoiding foods that aggravate symptoms.
  • Anal fissures can occur as a result of constipation. Pushing too hard during a bowel movement can stretch the skin around the anus resulting in small tears that cause pain, itching, and bleeding.
  • Hemorrhoids are also a possible complication associated with straining. Hemorrhoids are varicose veins of the rectum and can also cause rectal bleeding.
  • Fecal impaction is a condition where stool becomes stuck in the rectum. This may result in a healthcare professional having to manually remove the stool with a finger.
  • Rectal prolapse is also associated with constipation. This is a condition where the rectum actually comes out of the anus. Sometimes this can be reduced by pushing it back in, but it could potentially need surgery to repair.

Irritable bowel syndrome can also cause mental health complications associated with social isolation and fear of having symptoms such as diarrhea in public. Social anxiety, generalized anxiety, fear of public places, and depression can all worsen as a result of irritable bowel syndrome. Unfortunately, some of these mental health conditions can also be triggers for worsening irritable bowel syndrome symptoms creating a vicious cycle.

How Is Irritable Bowel Syndrome Diagnosed?

Irritable bowel syndrome is a clinical diagnosis, which means that there is no definitive test that can make the diagnosis. To make the diagnosis, your healthcare provider will take a detailed history and do a physical examination. There are diagnostic criteria for irritable bowel syndrome such as the Rome III criteria, but these are not usually used in clinical practice. The criteria include a discussion of the symptoms. Symptoms must be present for at least six months before the diagnosis can be made.

Basic laboratory tests may be done to rule out other conditions. Labs may include blood counts, chemistries, and thyroid studies. Stool studies are low-yield and should only be used if there are other concerning symptoms. A colonoscopy to evaluate the colon lining and possibly biopsies to rule out celiac disease (a wheat allergy) may also be performed if there is a concern raising the need for additional testing. If alarm symptoms such as anemia, weight loss, or bleeding are present, then a colonoscopy should be performed.

Irritable bowel syndrome can be grouped into 4 classifications:

  • Irritable bowel syndrome with constipation (IBS-C)
  • Irritable bowel syndrome with diarrhea (IBS-D)
  • Irritable bowel syndrome with mixed constipation and diarrhea
  • Irritable bowel syndrome not otherwise classified.

Non-prescription management of irritable bowel syndrome

Non-prescription treatments for irritable bowel syndrome include lifestyle changes and over-the-counter treatments.


Exercise has been shown to improve gastrointestinal function and decrease stress. This can help improve symptoms. One study showed that patients with irritable bowel syndrome who were randomized into a physical activity group had fewer symptoms than the control group (8% versus 23%).


Dietary modifications may have some benefits for individuals with irritable bowel syndrome, but studies are mixed. Exclusion diets have had some benefits, and dietary changes are still one of the most frequent non-pharmacologic treatments recommended. There is evidence that allergy or intolerance of food can be triggers of irritable bowel syndrome symptoms.


An increase in fiber intake from fruits and vegetables is associated with a decrease in bloating, and psyllium fiber supplements may be beneficial in some people. It seems to be most helpful in patients with irritable bowel syndrome with constipation. While fiber supplements improved bowel function, it was not found to improve abdominal pain.


Probiotics are another over-the-counter treatment frequently used for irritable bowel syndrome. There is evidence that probiotics may improve symptoms including abdominal pain, bloating, distension, gas, bowel changes, and gut microbiome.


Peppermint oil is another popular over-the-counter remedy for irritable bowel syndrome. The data are limited, but it may have some benefit for abdominal pain.

Medication management of irritable bowel syndrome

If your irritable bowel syndrome symptoms don’t respond to non-prescription management, your healthcare provider may choose to start medication to help control your symptoms. Many different medications may be used to help with your symptoms.


Antispasmodics work by trying to decrease cramping in the intestines. Antispasmodics relax the intestinal smooth muscle and reduce GI motility. The data supporting the use of antispasmodics is limited due to age and quality, but they are thought to be relatively safe.


Two primary classes of antidepressants can be used to treat irritable bowel syndrome symptoms. Both selective serotonin reuptake inhibitors (SSRIs) and tricyclic antidepressants (TCA) have good evidence for the treatment of irritable bowel syndrome.


Amitiza (lubiprostone) is used to treat irritable bowel syndrome with constipation as well as chronic constipation. The most common side effects are nausea, diarrhea, and headaches. Lubiprostone works by increasing fluid secretion into the intestines and is safe for long-term use.

Linzess (linaclotide) is another medication for irritable bowel syndrome with diarrhea, which works by increasing the secretion of fluid into the intestines. The common side effects are also nausea, diarrhea, and headaches.


Rifaximin is an old antibiotic used for the treatment of tuberculosis. It is marketed as Xifaxan for use with irritable bowel syndrome with diarrhea or mixed types. The medication is administered three times a day for 2 weeks.

Neomycin is used for the treatment of irritable bowel syndrome with constipation. It is used to treat bloating and constipation.

Opioid receptor agonist

Viberzi (eluxadoline) works on the opioid receptors in the brain but is not a pain medication. It is used to treat irritable bowel syndrome with diarrhea. Opioid receptors in the gut affect gastrointestinal motility, secretions, and sensation. Side effects of this medication include constipation, nausea, vomiting, bloating, and abdominal pain.

Irritable bowel syndrome can be extremely disabling and significantly impact your life. Monitoring your symptoms and communicating with your healthcare provider is the best thing you can do to take charge of your health. If you have known bowel triggers, then avoiding those triggers when possible is also important for your quality of life.

If your healthcare provider has recommended medication for migraines or any other condition, you may be wondering how to save money on your medications. Consider using our WellRx prescription discount card. Some people save a little. Some people save a lot and prices vary across zip codes. Even pharmacies across the street from each other can have huge price differences! ScriptSave has been helping consumers save on their prescriptions for 25 years.

Dr. Foglesong Stabile is a board-certified Family Physician who enjoys full scope Family Medicine, including obstetrics, women’s health, and endoscopy, as well as caring for children and adults of all ages. She also teaches the family medicine clerkship for Pacific Northwest University of Health Sciences.


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