Is your IBS really SIBO?

The prevalence of SIBO (small intestinal bacterial overgrowth) in IBS patients is between 19-37%. That’s right, many IBS smptoms might actually be caused by a bacterial imbalance in your gut.  


What is SIBO?


Our gut is home to an abundance of micro-organisms such as bacteria, parasites and fungi. Most of the bacteria live in the large intestine with much less living in the small intestine.


SIBO is the abnormal (over)growth of bacteria in the small intestines. Symptoms include nausea, reflux, abdominal cramping, bloating, flatulence, food intolerances and diarrhoea, the very same symptoms as IBS-D (diarrhoea).


IBS-C (constipation) may also be linked to SIBO although it tends to involve the overgrowth of different bacteria compared to diarrhoea-dominant SIBO and is both a cause and effect of slow bowel transit.  



What causes SIBO?



There are many risk factors that can cause SIBO including:

  • improper digestion of food (lack of digestive enzymes and stomach acid)
  • immunodeficiency
  • hypothyroidism
  • autoimmune conditions such as Coeliac disease
  • diverticulitis
  • diabetes
  • physical abnormalities from abdominal surgery
  • medications such as antibiotics, painkillers and PPI’s 
  • poor gut motility (constipation)
  • connective tissue disorders such as Ehlers Danlos Syndrome and scleroderma which affect the lining of the gut as well as other tissues in the body 
  • other imbalances in the gut such as candida overgrowth (often caused by over use of antibiotics)
  • food poisoning (“post-infectious” IBS)


The above factors can cause bacteria from the large intestine to migrate upwards to the small intestine or simply cause bacteria to overgrow in the small intestine.


Symptoms linked to SIBO


A bacterial overgrowth causes over fermentation of food by bacteria in the gut and that’s what causes the bloating, gas, bad breath, abdominal pain, food intolerances, diarrhoea and/or constipation as well as MANY other symptoms that aren’t linked to your gut such as:

  • hormonal symptoms
  • restless leg syndrome
  • inflammatory skin conditions like acne, psoriasis and eczema
  • fatigue
  • joint pain
  • depression
  • brain fog
  • headaches
  • liver inflammation such as non-alcoholic fatty liver disease
  • weight gain


SIBO can also cause other complications such as malnutrition, anaemia and intestinal damage resulting in malabsorption of nutrients.


What can we do about SIBO?


Thankfully there are ways to improve gut function and reduce the bacterial overgrowth so that we can either lessen or resolve these symptoms:

  • Supporting and restoring digestion: by using supplements as well as changing how and when we eat
  • Using herbal antimicrobial supplements to “kill” the overgrowth
  • Addressing other gut imbalances such as candida overgrowth using natural antifungal supplements
  • Restoring regular bowel movements where possible with diet and lifestyle changes and in some cases supplements known as prokinetics 
  • Immune system support to help the gut fight off the overgrowth
  • Calming down gut inflammation with an anti-inflammatory diet and eliminating foods we are intolerant to
  • Healing and repairing the gut lining that may be damaged due to the bacterial overgrowth
  • Nutritional supplements to address any nutritional deficiencies or malabsorption caused by SIBO
  • A short-term low-FODMAP diet, or for some a longer-term low-FODMAP diet may be needed (a low FODMAP diet is low in fermentable carbohydrates that can otherwise exacerbate bacterial fermentation in the gut)


Conventional treatment of SIBO uses antibiotics to kill off the bacterial overgrowth. Several rounds of antibiotics are often needed and the relapse rate is high when only using antibiotics to treat the overgrowth. Herbal therapies have been found to be as effective as antibiotics and are much cheaper.  We really need to take a more holistic approach and address the underlying cause rather than just try to kill the bacteria.

Getting the antibiotics prescribed here in the UK can also be difficult. Some people pay privately and the antibiotics cost around £200-300 per round of treatment.

*SIBO is considered to be a relapsing condition unless the underlying cause is well managed or addressed.




The symptoms of IBS and SIBO overlap considerably. Your IBS-C or IBS-D might really be a bacterial overgrowth that has many causes and consequences – not just relating to your gut but also your whole body, hence why it can cause so many symptoms that vary from person to person.

Breath testing is used to find out if you have a bacterial overgrowth in your small intestine. It measures the gases coming from bacterial fermentation in your small intestine. Get in touch if you’d like to find out more about SIBO testing and how to restore your gut health naturally!



Chedid, V., Dhalla, S., Clarke, J.O. et al. 2014. Herbal Therapy Is Equivalent to Rifaximin for the Treatment of Small Intestinal Bacterial Overgrowth. Global Advances in Health and Medicine. 3(3), pp.16–24.

Dukowicz, A.C., Lacy, B.E. and Levine, G.M., 2007. Small intestinal bacterial overgrowth: a comprehensive review. Gastroenterology & hepatology, 3(2), pp.112–22.

Rezaie, A., Pimentel, M. and Rao, S.S., 2016. How to Test and Treat Small Intestinal Bacterial Overgrowth : an Evidence-Based Approach. Curr Gastroenterol Rep. DOI 10.1007/s11894-015-0482-9