IBD vs. IBS: Understanding the Differences

How Are Symptoms Different?

IBS and IBD have some similar symptoms. However, each disorder also presents differently among different people. 

Similar Symptoms

Some symptoms related to both IBS or IBD are:

• Abdominal (belly) pain
• Bloating
• Bowel urgency (needing a toilet immediately)
• Diarrhea and/or constipation
• Gas
• Mucus in the stool
• Nausea

Distinct IBS Symptoms

Symptoms of IBS (gas, pain, bloating, diarrhea and/or constipation) can all occur with IBD. One difference is that with IBS, abdominal pain improves after a bowel movement.

Distinct IBD Symptoms

Symptoms of IBD that are not a part of IBS include:

• Blood in the stool
• Fever
• Pain in the joints
• Weight loss

Causes

The causes of both IBS and IBD are poorly understood. More than one factor may lead to the onset of these disorders.

IBS

IBS has many causes, and developing IBS might result from one or more factors. Key to this is the brain-gut interaction. Your brain and gut have two-way communication through the nervous system, which is essential for normal functioning.

It’s thought that IBS results from changes to the nervous system and its role in digestive functions. The digestive system becomes more sensitive to food, emotional stress, or foreign organisms (viruses or bacteria). These changes to the nervous system could be caused by:

• A breakdown in the communication between the brain and the gut
• A digestive infection (including small intestinal bacterial overgrowth [SIBO])
• Changes in the gut microbiome (the bacteria, viruses, and other microbes that live in the digestive tract)
• Stress or adverse events (especially in early childhood)

Risk factors for IBS include:

• Anxiety, depression, or post-traumatic stress disorder
• Experiencing trauma (especially sexual)
• Female sex
• Genetic factors (a tendency may be inherited)

IBD

The causes of IBD aren’t well-defined or understood. A genetic predisposition plus an environmental trigger cause IBD. Together, these factors lead to an inappropriate inflammatory response centered on the digestive system.

Some suspected environmental triggers are:

• A change in the microbiome (caused by diet, environment, or antibiotics)
• Exposure to pesticides
• Psychological stress
• Smoking cigarettes
• Ultra-processed foods

Risk factors for developing IBD include:

• Anxiety or depression
• Antibiotics in early childhood
• Formula feeding in infants
• Having a close family member with IBD
• Low dietary fiber intake
• Stressful life events
• Vitamin D deficiency

How They Are Diagnosed

Diagnosing IBS or IBD is not always easy. IBS is diagnosed by applying standard criteria to a person’s history of symptoms and physical exam. IBD is frequently diagnosed with endoscopy (a procedure that looks inside the body using a flexible tube with a camera and tools), such as an upper GI or a colonoscopy.

IBS

The Rome Criteria are used to diagnose IBS based on the symptoms the person experiences. The most important symptom is abdominal pain at least one day each week during the previous three months.

Diarrhea, constipation, or a combination of these are also part of a diagnosis, resulting in categorizing it into subtypes based on these. The subtypes are IBS-D (IBS with diarrhea), IBS-C (IBS with constipation), or IBS-M (IBS with mixed symptoms).

An endoscopy procedure, such as a colonoscopy, does not diagnose IBS. It will not show any disease because IBS does not cause inflammation.

Blood in the stool, fever, and weight loss are not IBS symptoms.

IBD

IBD causes ulcers and inflammation in the digestive system. Along with the symptoms and the results of lab tests, finding changes in the digestive tract during an endoscopy points toward an IBD diagnosis. Diagnosing IBD may also include stool tests, a CT scan, and/or an MRI.

People can have both IBD and IBS. Some people with IBD in remission (the disease is no longer active) could still have symptoms. The cause of those symptoms could be IBS.

Treatment Differences

Medications for managing IBS and IBD differ. Surgery is one treatment for IBD, but it is not used for IBS.

IBS

The type of IBS dictates the medications used.

Some of these medications include:

• Antispasmodics such as Bentyl (dicyclomine), cimetropium, Buscopan (hyoscine), otilonium bromide, and pinaverium bromide, for any form of IBS
• Imodium (loperamide), an over-the-counter antidiarrheal used for IBS-D
• Intestinal secretagogues, Amitiza (lubiprostone), Ibsrela (tenapanor), Linzess (linaclotide), and Trulance (plecanatide), for IBS-C
• Laxatives, over-the-counter medications for IBS-C
• Lotronex (alosetron), a 5-HT3 antagonist for IBS-D
• Lyrica (pregabalin), an anticonvulsant, for any form of IBS
• Selective serotonin reuptake inhibitors (SSRIs), such as Prozac (fluoxetine), for any form of IBS
• Tricyclic antidepressants (TCAs), amitriptyline or desipramine, for any form of IBS
• Viberzi (eluxadoline), an opioid for IBS-D
• Xifaxan (rifaximin), an antibiotic for IBS-D
• Zelnorm (tegaserod), a 5-HT4 agonist for IBS-C

IBD

Many medication types are available to treat IBD, Including:

• Aminosalicylates (5-ASA), including Azulfidine (sulfasalazine), Dipentum (olsalazine), and mesalamine (Apriso, Canasa, Lialda, Pentasa, and Rowasa)
• Antibiotics including Cipro (ciprofloxacin) and Flagyl (metronidazole)
• Biologics and their biosimilars, including Cimzia (certolizumab pegol), Entyvio (vedolizumab), Humira (adalimumab), Remicade (infliximab), Simponi (golimumab), Skyrizi (risankizumab), Stelara (ustekinumab), Tremfya (guselkumab), Tysabri (natalizumab)
• Corticosteroids such as budesonide (Entocort and Uceris) and prednisone
• Immunomodulators including Imuran (azathioprine), Neoral (cyclosporine), methotrexate, Purinethol (mercaptopurine, 6-MP)
• Small molecules, including Rinvoq (upadacitinib), Velsipity (etrasimod), Xeljanz (tofacitinib), Zeposia (ozanimod)

Surgery is also a treatment for IBD. Types of surgery for IBD include:

• Colectomy, which is removing the colon
• Colectomy with ileal pouch-anal anastomosis (IPAA), where the small intestine is made into an internal pouch to hold stool
• Ileostomy, which is removing the colon, and a piece of the small intestine is brought through the abdomen to release stool (called a stoma)
• Fistula surgery, which repairs an abnormal tunnel between two organs
• Proctectomy, which is removing the rectum and anus
• Resection, which is removing a piece of intestine and reconnecting the two healthy ends
• Strictureplasty, which opens up narrowed parts of the intestine (called strictures)

How to Manage IBD or IBS

IBS

Some of the changes to diet and lifestyle recommended for IBS include:

• Avoiding foods that cause symptoms
• Adding more fiber to the diet (with caution to avoid bloating or other symptoms)
• Eating smaller meals on a regular schedule
• Getting more exercise
• Managing stress and trialing yoga, mindfulness, and meditation
• Receiving treatment for mental health concerns (such as with gut-directed psychotherapy)
• Reducing caffeine and alcohol
• Trying a diet low in carbohydrates called FODMAPs (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols)
• Trying a peppermint oil supplement

IBD

Changes to diet and lifestyle recommended for people with IBD often include:

• Addressing mental health through various forms of therapy
• Eating a diet that includes a variety of fruit, vegetables, cereals, grains, nuts, seeds, and low-fat protein sources
• Getting physical activity
• Taking a vitamin D supplement if needed
• Trying the low-FODMAP diet with suspicion of IBS

Complementary and alternative medicine with less evidence showing benefits include:

• Acupuncture
• Cannabidiol (CBD) supplements
• Fish oil supplements
• Probiotics (beneficial microbes)
• Prebiotics (specialized plant fibers that feed the beneficial microbes in the gut)
• Turmeric supplements

When to See a Healthcare Provider

Having diarrhea, constipation, and bloating at certain times is common. When they become troublesome or last for more than a few days, seek care from a healthcare provider.

Abdominal pain is another reason to see a healthcare provider. If the pain is sudden and severe, head to a hospital emergency department.

Red flag symptoms (reasons for emergency care or an urgent appointment with a healthcare provider) include:

• Altered mental state, like confusion
• Blood in the stool
• Dizziness
• Losing consciousness
• Stool that appears black or tarry

Summary

IBS and IBD are different conditions, though both may occur in the same person. IBD causes inflammation that leads to a host of possible effects both inside and outside of the digestive system. It is diagnosed with testing that includes endoscopy, blood work, and sometimes other imaging.

IBS causes bloating, pain, diarrhea and/or constipation, but it does not cause inflammation. IBS and IBD are managed with different medications and lifestyle changes, making it essential to get a diagnosis.