Symptoms of IBS


IBS symptoms vary according to the person. Common symptoms include:

  • Abdominal pain (sometimes relieved in part/entirely with bowel movements or passing gas. Often after eating.)
  • Flatulence
  • Bloating or distension
  • Diarrhoea
  • Constipation
  • Alternating diarrhoea and constipation (i.e., IBS with mixed bowel habits)
  • Mucus in stool
  • Nausea


Researchers have yet to establish the cause of IBS, and as such there is no specific test that can establish whether someone has it or not. As such, IBS is diagnosed by assessing for the presence of common IBS symptoms and ruling out other conditions which share the same symptoms.There are several illnesses or conditions which can potentially mimic the symptoms of IBS. Including:

  • Inflammatory bowel disease (Crohn’s disease, ulcerative colitis)
  • Coeliac disease (inflammatory condition caused by a reaction to gluten)
  • Severe stress (i.e., stressful events can increase contractions in the gut, leading to diarrhoea)
  • Lactose intolerance (i.e., inability to process the sugar, lactose, found in dairy products)
  • Colon cancer

When assessing for IBS, doctors rely on the patient satisfying the Rome IV criteria. These criteria were developed through the collaboration of international experts in functional gastrointestinal disorders (FGIDs). To satisfy the conditions for IBS, a person must experience recurring abdominal pain for an average of at least one day per week in the previous 3-month period that satisfies two or more of the following criteria:

  1. Related to defecation

  2. Associated with a change in the frequency of stool

  3. Associated with a change in the form (appearance) of stool


IBS symptoms in detail

Abdominal pain

Abdominal pain is one of the most common symptoms described by IBS patients. It is often described as occurring in the lower section of the abdomen and may be relieved or exacerbated having a bowel motion. Management of abdominal pain can constitute a large part of managing your IBS. Abdominal pain is often described as being “cramp-like”, “sharp”, or “stabbing”.

Pain relief methods include:

  • Anti-spasmodic medications (e.g., hyoscine, mebeverine)
  • Applying heat to the abdomen(e.g., hot water bottle, heat pack)
  • Over-the-counter pain relief drugs (e.g., paracetamol)
  • Prescription low-dose tricyclic antidepressants (e.g., amitriptyline) can provide a pain relief effect
  • Peppermint oil capsules
  • Psychologically based pain relief methods (e.g., cognitive behavioural therapy, acceptance and commitment therapy)

Abdominal treatment can also be reduced by implementing dietary changes. By avoiding ‘trigger’ foods, you can reduce instances of avoidable and disruptive abdominal pain.


Those with diarrhoea-predominant IBS or IBS with mixed bowel habits will experience diarrhoea as a symptom of their IBS.Diarrhoea can be particularly disruptive due to the need to frequently or urgently use the toilet. This can cause anxiety around being near a toilet, especially in unfamiliar or new places. Increasing dietary fibre intake can help limit diarrhoea by decreasing the passage of food through the digestive tract. Fibre intake can be increased through either changing one’s diet to include more fibre dense foods (e.g., beans, grains, cereals) or taking a fibre supplement (e.g., psyllium husk). There are a variety of available fibre supplements available and their effects can vary. A doctor or dietitian can help you find a supplement and dosage that works best for you. Antidiarrheal drugs (e.g., Imodium) are another option for dealing with an acute bout of diarrhoea. Again, these come in different forms and you should discuss your options with your doctor.


Constipation is a common symptom for individuals with constipation-predominant IBS or IBS with mixed bowel habits.It is often associated with abdominal pain and feeling bloated. The adequate dietary fibre and water intake can help reduce instances of constipation –modifying the diet with fibre-rich foods and/or fibre supplements can help here. You may also find relief through various over the counter medications (e.g., stimulant and osmotic laxatives, emollients) but these should be taken under your doctor’s supervision. Other treatment options include the prokinetic drug Prucalopride, which prevents constipation by stimulating the smooth muscle of the colon, increasing contractions and facilitating the passage of bowel contents. In Australia, Prucalopride is considered in cases of adult patients that have failed to respond to treatment with laxatives.


Feeling bloated or full is regular issue for many with IBS. Aside from the discomfort, bloating can make you feel self-conscious, especially if you feel as if your belly is visibly distended. Aside from avoiding your trigger foods, you may find that taking smaller, regular meals helps reduce bloating. Regular exercise can also help improve bowel function and may reduce bloating.

Psychological symptoms

It is not uncommon for individuals with IBS to report feelings of psychological distress. This can include feeling anxious, worries, depressed, or mentally exhausted. Feelings such as these can be caused by the long-term experience of unpleasant symptoms of IBS (e.g., diarrhoea, bloating, pain, constipation), or the practical consequences of these symptoms, that is, theirinterference in day-to-day obligations (e.g., work, study, parenting) and enjoyable activities (e.g., hobbies, socialising).The research tells us that the digestive tract and brain have a reciprocal relationship, often referred to as the Gut-Brain or Brain-Gut axis. Simply put, our mental state can modulate the behaviour of the digestive tract (e.g., increasing intestinal contractions/passage of stool) and our gut/gut microbiome can influence our mental state.Psychological distress can exacerbate digestive symptoms and the experience of digestive symptoms can exacerbate our mental state in kind. It is therefore important to takegy notice of your mental health and to realise when stress extends beyond your ability to cope. Consultation with a psychologist can help with this, as they can assist you with evidence-backed strategies for managing IBS. Your doctor can also talk you through any medication options that are available to help reduce psychological distress.