What is IBS?

Irritable bowel syndrome (IBS) is a gastrointestinal disorder that affects the colon, i.e., small intestine [1]. About 20% of men and women suffer from IBS. It is characterized by cramps, bloating, diarrhea, and bouts of constipation.

IBS refers to a group of symptoms – including abdominal pain and changes in the pattern of bowel movements – without any evidence of underlying damage. These symptoms occur over an extended period, in repeated episodes for years.

Pain and cramping are caused by visceral hypersensitivity, which means the nerves within your colon are hypersensitive to stimulation and pressure [2].


Potential Triggers

Gut-Brain Axis Dysregulation

Your gut and brain work together in cooperation to control digestion. IBS disrupts the communication between the gut and brain [3].

Abnormal communication between the brain and gut may speed up or slow down the typical transit time of stool. It may involve serotonin and gastrin, both of which control the nerve signals between the brain and the gut. As a result of the uncoordinated signals, you experience extreme tension in the muscles of the digestive tract.

Gut Motility Disorder

The wall of the intestine is lined with layers of muscles that contract as they transport food along the digestive tract. In a regular bowel movement, the gut contracts and relaxes rhythmically.

In IBS, however, the rhythm is disrupted – it either speeds up or slows down gut muscle contractions. IBS happens when the muscles of your colon contract either too slowly or too forcefully. Contractions that are stronger and more persistent than usual can cause gas, bloating, and diarrhea. On the other hand, weak contractions of the abdominal muscles can slow food passage and lead to hard, dry stools.

Gut Inflammation and Infection

Some people with IBS have an abnormally high number of immune cells in their intestines [4]. This immune response leads to pain and diarrhea (gastroenteritis).

In turn, diarrhea can worsen the symptoms of IBS, causing a vicious cycle [4].

Changes in Gut Microbiota

Microbiota is the “good” bacteria that reside in the intestines.

Research indicates that the microbiota in IBS patients might differ from that in healthy people [3]. Individuals with IBS have decreased range and numbers of Bacteriodetes microbiota.


IBS Classification

IBS is classified into four main types – depending on whether diarrhea or constipation are common symptoms, both are common, or neither are common.

IBS with Constipation (IBS-C)

Constipation-predominant IBS is the most common type of IBS, affecting nearly 50% of people with IBS. You may feel stomach pain, discomfort, bloating, infrequent or delayed bowel movements, or hard or lumpy stools [5].

IBS with Diarrhea (IBS-D)

Diarrhea-predominant IBS affects one-third of patients with IBS. You may experience stomach pain, discomfort, an urgent need to go to the toilet, frequent bowel movements, or loose stools.

IBS with Alternating Stool Pattern (IBS-A)

Although it seems counterintuitive, about 20% of patients with IBS experience alternating episodes of constipation as well as diarrhea.

IBS-A tends to be more severe than others – with more frequent and intense symptoms. Because the symptoms .of alternating IBS vary from one person to another, you would need an individualized treatment approach for your specific symptoms.


Risk Factors

Food Sensitivity

Particular foods can trigger IBS symptoms. Some common triggers include FODMAPs, caffeine, lactose, and gluten [6].

FODMAP foods refer to foods that are high in fermentable oligo-, di-, monosaccharides, and polyols. These are types of carbohydrate increase the amount of water entering the gut, and gut bacteria may cause them to ferment – causing an increase in irritation of the gut and an increase in intestinal gas.

Diet triggers for IBS-Constipation:

  • Bread and cereal made with refined (not whole) grains
  • Processed foods such as cookies and chips
  • Coffee, carbonated drinks, alcohol
  • High-protein diets
  • Dairy products, especially cheese

Diet triggers for IBS-Diarrhea:

  • Insoluble fiber
  • Foods and drinks with chocolate, alcohol, caffeine, fructose, or sorbitol
  • Carbonated beverages
  • Heavy meals
  • Fried and fatty foods
  • Dairy products
  • Gluten products

Age under 45

IBS affects people of all ages, but most people begin to notice the symptoms when they’re young adults between 20 to 30 years old.


IBS is more common among women – about twice as many women as men have the condition.

Furthermore, symptoms of IBS in women tend to worsen during menstrual periods, suggesting that female hormone plays a primary role.

Anxiety is also one of the possible reasons for gender-related traits. Women tend to be more susceptible to stress, which in turn may lower the pain thresholds in women, putting them at higher risk for IBS.

Estrogen therapy before or after menopause is also a risk factor.

Mental Health

Anxiety, stress, and depression are associated with IBS. It’s not clear what comes first – the mental health issues or the IBS.

A history of sexual abuse might also be a risk factor, with as many as 33% of IBS patients reporting such abuse [7]. Because women are at higher risk of sex-related abuse, it may contribute to the higher rate of IBS in women as compared to men.


IBS in Men vs. in Women

Men are less likely to develop IBS – possibly due to their higher levels of testosterone or other androgens (male hormones) compared to women [8]. Higher levels of androgens lower men’s risk of developing chronic pain disorder and may act as an endogenous pain reliever [9]. On the other hand, estrogen – which is higher in women – is thought to increase gut sensitivity and therefore enhance the risk of IBS [10]. This might explain why pain is a predominant symptom of IBS in women, but not in men.

The gender differences in the prevalence of IBS tend to decrease with age. The rate of IBS in women begin to drop after the age of 45, a trend that’s generally attributed to menopause [11].

Men with IBS have a poorer quality of life as compared to women [12]. Dysphoria, body image, interference with daily activities, health concerns, food sensitivity, and sexual vitality are more significantly diminished in men. If you are a guy with persistent stomach discomfort, don’t discount the possibility that you might be dealing with IBS.

In general, women with IBS more commonly experience constipation, while men are more likely to experience diarrhea.



IBS causes repeated episodes of stabbing abdominal pain, along with chronic constipation, frequent bouts of diarrhea, or both. While IBS can cause persistent discomfort, most people will not experience severe complications.

Abdominal Cramps and Discomfort

You may experience pain and cramps, usually in the lower abdomen. The pain may radiate to other parts of the abdomen.

This discomfort is likely due to the oversensitivity of the gut. In response to a trigger, the muscles of the gut may contract more aggressively than they need to. Excessive gut muscle contracts may lead to pain and cramps, which may dissipate following a bowel movement.

Excess Gas and Bloating

People with IBS may experience excessive gas and bloat. There are two potential causes:

  • Leaky Gut. IBS may cause the bacteria in the gut to leak out with toxins that may cause excessive gas.
  • Hypersensitivity to gas. Some people are less able to tolerate and transport gas. They, therefore, feel gassier than other people.

Irregular Bowel Movements

IBS changes the transit time of stool. This, in turn, alters the amount of water in the stool, giving stools a range from loose and watery to thick and dry consistency.

Slow-moving stool in the intestine often become dehydrated as the intestine takes in the water. In turn, this hardens the stool, which can lead to constipation.

On the other hand, quick movement of stool through the intestine leaves little time for water absorption. This results in the loose stools characteristic of diarrhea.


Frequent, loose, and watery stools can occur in patients with diarrhea-predominant IBS. The stools may also contain mucus.

Diarrhea happens when the muscles in the gut contract more than they need to. Abdominal cramps might accompany it. Accelerated bowel movement can also result in a sudden, immediate urge to have a bowel movement.

Some patients describe diarrhea as a significant source of stress – even avoiding social events for fear of a sudden onset of diarrhea.


IBS can cause constipation by preventing the gut muscles from contracting as much as they should. When the bowel transit time slows down, the bowel absorbs more water from stool, making it more difficult for the stool to pass.

You may experience:

  • Fewer than three bowel movements per week
  • Hard, dry, or lumpy stools
  • Difficulty or pain when passing stool
  • A feeling of an incomplete bowel movement

The pain and discomfort may ease bowel movement.

You may also experience alternating episodes of diarrhea and constipation. Throughout each episode, you continue to experience chronic and recurring abdominal pain.

Food Intolerance

You may be more sensitive to food that is rich in certain types of carbohydrate. More specifically, you feel irritation in the gut when you ingest high-FODMAP foods. As mentioned above, FODMAP is an acronym for fermentable oligo-, di-, monosaccharides, and polyols. FODMAPs can increase the amount of water entering the gut, and in return, the gut bacteria ferment them, triggering IBS symptoms [13].

Fatigue and Insomnia

About 50% of people with IBS report fatigue. In one study, IBS patients described low stamina that restricts daily activities such as work, leisure, and social interactions [14]. Intestinal gas and bloating may also be linked to brain fog, which is characterized by mental confusion, impaired judgment, and trouble concentrating.

IBS is also related to insomnia – difficulty falling asleep, frequently waking in the middle of the night, and feeling unrested the following day. In a study of 112 IBS adult patients, 13% reported poor sleep quality [15].

Fatigue and poor sleep quality also correlate to more severe gastrointestinal symptoms. A study of 85 adults found that the intensity of their symptoms predicted the severity of fatigue [16].


There is a strong reciprocal link between IBS and stress due to tight gut-brain communication. Feeling stress can worsen IBS symptoms, and IBS symptoms can cause stress. Hence, this means IBS can create a vicious cycle of digestive symptoms that increase anxiety and vice versa.

It’s unclear whether IBS symptoms are due to stress or whether the stress of living with IBS makes people more prone to anxiety. Whichever comes first, anxiety and digestive abnormalities reinforce one another in a vicious cycle.


Rome IV criteria are the standard diagnostic guideline for IBS. It requires you to have the symptoms weekly in the last three months and that the recurring symptoms started at least six months prior. But most doctors don’t follow this guideline religiously because it’s challenging for patients to recall the exact number of months they had symptoms in the preceding year.

To determine whether your digestive discomfort is truly IBS, doctors need to check that at least two out of the following are present:

  • A bowel movement relieves the ache
  • A change in how often the stool passes out
  • The stool looks different

Symptoms that are NOT typical of IBS:

  • Blood in stool
  • Unexplained weight loss
  • Family history of inflammatory bowel disease
  • Fever
  • Rectal bleeding
  • Iron-deficiency anemia
  • Difficulty swallowing


Foods to Avoid


Although trigger foods can be different for each person, doctors have identified FODMAPs as a common trigger of IBS. A diet low in FODMAPs may alleviate IBS symptoms [17].

The low FODMAP diet focuses on reducing or eliminating fermentable, short-chain carbohydrates because of its poor absorption in the small intestine [17]. More specifically, FODMAPs increase fluid in the bowel and create more gas, resulting in abdominal discomfort.

You may be able to reduce the symptoms of IBS by avoiding high-FODMAP foods, which include:

  • Some vegetables (e.g., onions, garlic, cabbage, broccoli)
  • Beans and lentils
  • “Stone” fruits (e.g., peaches, plums, prunes, mangoes, apples, pears, watermelon)
  • Dried fruits and fruit concentrate
  • Wheat and rye (e.g., bread, cereal, pasta, crackers, pizza)
  • Dairy (e.g., milk, soft cheese, yogurt, custard, pudding)
  • Nuts (e.g., cashews, pistachios)
  • Sweeteners and artificial sweeteners (e.g., high fructose corn syrup, honey, sorbitol)
  • Drinks (e.g., alcohol, sports drink, coconut water)

Avoid foods that contain FODMAPs for approximately four weeks. Once you are through this period, and your symptoms have improved, you may then systematically reintroduce each FODMAP type one at a time and assess for any ongoing hyperreactivity.

AVOID Insoluble Fiber

Insoluble fiber can worsen diarrhea in some people with IBS. Soluble fiber is, on the other hand, acceptable and may be beneficial.

AVOID Gluten

Gluten is a type of protein that some people are allergic to and may cause symptoms of diarrhea-predominant IBS [18]. The good news is that gluten-free foods, which is widely available in the market, may alleviate symptoms of IBS.


Dairy is problematic for two reasons:

  • It contains fat, which can trigger diarrhea. Switch to low-fat or non-fat dairy to mitigate symptoms.
  • Many IBS patients are intolerant to lactose; you may want to consider dairy-free alternatives like soy cheese and rice milk.

If you need to cut our dairy completely to alleviate symptoms of IBS, you can consider a calcium supplement for nourishment.

AVOID Fried and Processed Foods

Practice moderation with fried foods. The high-fat content may be especially challenging on your digestive system if you have IBS. The chemical makeup of food changes when fried, making it more difficult to digest.

Likewise, avoid processed foods. Processed foods often contain preservatives or additives that might trigger IBS flare-ups.

AVOID Sweeteners or Artificial Sweeteners

Sweeteners such as sucralose, acesulfame, and aspartame are tricky for your body to absorb, especially when you have IBS.

AVOID Caffeine

Some people swear by their morning coffee. But like all caffeinated drinks, coffee triggers the hyperreactivity of the gut. If you need an energy boost, consider a nootropic supplement or going for a brisk walk instead.

Chocolate can also trigger IBS due to its concentration of caffeine and sugar content. Vegan chocolate might be a more tolerable alternative.

AVOID Alcohol

Alcoholic beverages are a trigger for people with IBS. Beer contains gluten and wine contains sugar – both of which are IBS triggers. Alcohol can also be dehydrating, which can impede liver function and digestion.

Limiting alcoholic beverages may help reduce the symptoms related to IBS. Consider a gluten-free beer or a plain seltzer instead.


Overcoming IBS


Probiotics are the “beneficial” bacteria that reside in the gut. Its found in certain foods, such as Greek yogurt and dietary supplements. A recent study shows that certain probiotic strains may relieve IBS symptoms, such as abdominal pain, bloating, and diarrhea [19].


Mesalazine (5-aminosalicylic acid). There is increasing evidence for the efficacy of mesalazine in the treatment of IBS [20]. Mesalazine has anti-inflammatory properties that reduce IBS symptoms by alleviating gut inflammation.


Treatment for IBS-C

High-Fiber Diet

Fiber mitigates constipation by softening stools, making it easier to pass. It expands the inside of the digestive tract and promotes regular bowel movement. In return, this reduces the chance it will spasm as it transmits and digests food.

Ideal sources of fiber include whole-grain bread and cereals, fruits, vegetables, and beans. If you plan to incorporate high-fiber foods into your diet, do it gradually over weeks. Overconsumption of fiber may cause diarrhea, bloating, and discomfort.

Some people use bulking agents, known as fiber supplements, to treat IBS-C. These include wheat bran, calcium polycarbophil (Fibercon), corn fiber, and psyllium (e.g., Fiberall, Metamucil, Perdiem). Fiber supplements might cause fewer side effects such as gas and bloat as compared to fiber-rich foods.


Laxatives help you go to pass stools more easily. But beware of the type of laxative you’re taking – some can be habit-forming and possibly harmful when taken long-term.

Stimulant laxatives. Examples include bisacodyl (Correctol, Dulcolax), sennosides (Ex-lax, Senokot), castor oil, and cascara. With these laxatives, the active ingredients trigger the bowel muscles to contract, moving stool through.

Osmotic laxatives. Examples include prescription lactulose and OTC polyethylene glycol (Miralax). They soften stools by absorbing water back into the colon, allowing the stool soften and pass more quickly. Osmotic laxatives are considered safe for long-term use but may be associated with side effects such as diarrhea, dehydration, and bloating.

Prescription Medication

Linaclotide (Linzess) treats IBS in men and women who failed to respond to other treatments. It helps relieve constipation by facilitating increasing fluid secretion in the gut, which in return, facilitate bowel movements and passing of stools.

Plecanatide (Trulance)is a prescription that treats IBS-C without the common side effects of cramping and abdominal pain [21]. It increases gastrointestinal fluid in your gut and encourages regular bowel movements.

Lubiprostone (Amitza) is a type of laxative that may be used to treat severe IBS-C in women who do not respond to other treatments. It works by increasing secretion of fluid in the small intestine to soften stools and help with its passage. Common side effects include abdominal pain, nausea, and diarrhea.


Treatments for IBS-D

Dietary Modifications

Digestion and food triggers are different for everyone. Some people with IBS can tolerate certain foods, while others may not. Nevertheless, the following nutritional modifications may alleviate diarrhea.

Low FODMAP diet. As mentioned above, a low FODMAP diet can reduce IBS symptoms [17]. Avoid foods that contain FODMAPs for approximately four weeks. Once you are through this period, and your symptoms have improved, you may then systematically reintroduce each FODMAP type one at a time and assess for any ongoing hyperreactivity.

Avoid Gluten and Lactose. Many people who experience IBS symptoms are also simultaneously allergic to gluten or lactose. Cutting foods that contain gluten or lactose may help alleviate the symptoms.

Avoid Caffeine and Alcohol. Coffee and alcohol can trigger gut hyperreactivity.

Avoid Sweeteners. Sweeteners or artificial sweeteners are tricky for your body to absorb, especially when you have IBS. Avoid ingredients such as sugar, sucralose, acesulfame, and aspartame.

Take Probiotics. Foods and supplements that are rich in probiotic strains may help relieve IBS symptoms such as abdominal pain, bloating, and diarrhea[19]. Examples of food that are rich in probiotics include Greek yogurt, kefir, sauerkraut, tempeh, kimchi, miso, kombucha, and pickles.

Take peppermint. Peppermint is an antispasmodic that helps to relax the abdominal muscles. It might relief IBS symptoms in the short term, but research results are inconsistent.

Take soluble fiber. A moderate amount of soluble fiber can add bulk to your stools. Good sources are oats, barley, whole grain, and dried fruits.

Eat smaller portions. Eating small meals throughout the day would help to reduce the hyperreactivity of your digestive system.

Drink more water. Diarrhea can cause dehydration. Hence, it’s imperative to drink at least six to eight glasses of water a day. Do not drink water while you eat – drink one hour before or after eating instead.

Stress Relief

Stress and anxiety can worsen IBS symptoms, including diarrhea. That’s why it’s essential to manage your mood and stress levels.

Choose healthy habits. Eat a well-balanced diet. Get regular exercise and sufficient sleep. Progressive relaxation exercises can help you relax muscles in your body, one by one.

Counseling. Learn to calm down with behavioral therapy. There are a few types: relaxation therapy, hypnotherapy, biofeedback, psychotherapy, and cognitive-behavioral therapy. A counselor can help you address your stress response. Biofeedback is electric sensors that help you focus on relaxing specific muscles to relieve stress.

Over-the-counter Medications

Loperamide (Imodium). This anti-diarrheal medication may help control diarrhea by slowing down the contractions of abdominal muscles. This, in turn, decreases the number of bowel movements and makes the stool less watery.

Dicyclomine (Bentyl) is a form of anticholinergic medication that can help relieve painful bowel spasms by relaxing the smooth muscles of the gut. These medications are generally well-tolerated but can cause constipation, dry mouth, and blurred vision.

Eluxadoline (Viberzi) can ease diarrhea by reducing muscle contractions and fluid secretion in the intestine and increasing muscle tone in the rectum. The side effect can include nausea, abdominal pain, mild constipation, and pancreatitis.

Alosetron (Lotronex) relaxes the colon muscles and slow the movement of waste through the bowel. It is only approved for short-term treatment use in women with severe chronic IBS-D who has failed to respond to other treatment options. Severe and unpredictable gastrointestinal side effects have been reported (including death). Your doctor must be registered with the pharmaceutical manufacturer to prescribe the medication.

Bile acid sequestrants. Your doctor might prescribe a bile acid binder, such as cholestyramine (Prevalite), colestipol (Colestid), or colesevelam (WelChol). They prevent diarrhea by binding bile acids in the intestines and reducing stool production.

Rifaximin (Xifaxan) is an antibiotic that decreases gut bacterial overgrowth and diarrhea.


Conditions that seem like IBS but AREN’T

IBS is not the only explanation reason for the symptoms mentioned in this article. It is best to consult a doctor to get a proper diagnosis.

Here is a list of examples of conditions that seem like IBS but aren’t:

  • Ulcerative colitis
  • Microscopic colitis
  • Crohn’s disease
  • Celiac disease (gluten allergy)
  • Lactose intolerance
  • Diverticulitis
  • Gallstones (sharp pain on the right side of the abdomen)
  • Pancreatitis
  • Endometriosis (symptoms similar to IBS, but may worsen with a menstrual period)
  • Stomach cancer (heartburn, vomiting, blood in the stool, weight loss)
  • Parasites


The Bottom Line

IBS is a chronic health condition that can affect your quality of life. Dietary modifications, stress management, and prescription medications may alleviate symptoms of IBS, but there is no known cure. Avoid foods that trigger your symptoms. Symptoms improve as you learn to manage the condition. Visit your doctor to get or rule out IBS diagnosis.