Many people live with ongoing gut discomfort that never seems to fully improve, even after trying traditional ways to improve their gut health. If that sounds familiar, there may be another explanation – Small Intestinal Bacterial Overgrowth (SIBO).
SIBO occurs when bacteria that usually live in the large intestine begin to accumulate in the small intestine, a place they’re not meant to thrive. This shift can interfere with digestion, trigger inflammation, and cause a range of symptoms that often look a lot like irritable bowel syndrome (IBS). In fact, SIBO is one of the most overlooked contributors to persistent gut symptoms.
At Tree of Life Nutrition, we understand that SIBO is a commonly missed contributor to long-standing digestive symptoms. Our gut-focused dietitians have extensive experience supporting clients through identifying whether SIBO is present, to guiding treatment and long-term recovery.
So what are the SIBO symptoms you need to be aware of? Below, we explore the most common signs of SIBO, and some others you may not have heard of. We also explain how recognising the pattern can lead to the right testing and long-awaited relief.
SIBO symptoms are often confused with IBS
At first glance, SIBO symptoms and IBS symptoms are almost identical. Both can involve bloating, changes in bowel habits, abdominal discomfort, and food-triggered reactions. With IBS being more widely known, it can often be assumed that IBS is the culprit for all persistent gut symptoms. While IBS and SIBO symptoms can overlap, they are not the same condition.
And while the two conditions share similar symptoms there are several symptoms which are more likely to be present with each condition. What’s more, the triggers are quite different, as are treatment protocols.
5 digestive SIBO symptoms you may have thought were just IBS
1. Abdominal pain and discomfort.
Abdominal pain is one of the most common symptoms of SIBO. This discomfort may feel like cramping, aching, or a general sense of irritation in the digestive tract. Because bacteria in the small intestine ferment carbohydrates prematurely, this creates gas and pressure that the small bowel isn’t designed to hold. Unlike IBS pain, which can come and go unpredictably, SIBO-related discomfort often appears soon after meals, particularly meals containing carbohydrates or fibre.
2. Excess gas or flatulence
If you’re experiencing ongoing gas, flatulence, or a sensation of bubbles in the gut, SIBO may be playing a role. Excess gas happens when accumulated bacteria ferment food before it reaches the large intestine. While gas is normal, frequent or socially disruptive flatulence may be a sign of SIBO. While it can also occur with IBS, a key difference is that frequency worsens after fermented or high-fibre foods.
3. Feeling uncomfortably full after meals
A common sign of SIBO, is a feeling of fullness after eating only a small amount. When gas and pressure build up quickly in the small intestine it leaves little room for food to move through comfortably. You may experience this as feeling full or tight after eating, or you could also feel that food is just sitting there and not digesting. This is also a common symptom of IBS, which can often lead to misdiagnosis, or diagnosis of SIBO alongside IBS.
4. Diarrhoea, constipation, or both
SIBO can affect bowel habits in different ways depending on the type of gas produced. Hydrogen-dominant SIBO often leads to looser stools or diarrhoea. While methane-dominant overgrowth (IMO) is commonly linked with slow transit and constipation. Mixed SIBO can alternate between both. These bowel-pattern changes can mirror IBS so closely that many people receive an IBS label without being investigated for SIBO.
5. Abdominal distension and bloating
Bloating and distension are hallmark SIBO symptoms. Many people describe looking six months pregnant by the afternoon, even if they woke up with a relatively flat stomach. Distension with SIBO is typically triggered after meals, and is worsened with high-fibre foods, probiotics or fermented foods. It is associated with discomfort relieved temporarily by passing gas.
The key clues that suggest SIBO (not just IBS)
SIBO symptoms are caused by bacteria being in the wrong place in our digestive system. How your gut reacts to certain foods and treatments can be the ‘pattern clues’ that help us identify the likelihood of the condition, and need for testing.
Fibre makes you feel worse. Fibre supplements like psyllium husk, PHGG or inulin should help IBS. But with SIBO, they often increase bloating because bacteria in the small intestine ferment them prematurely.
Even if your symptoms look like IBS, certain patterns are particularly suggestive of SIBO:
You feel worse on probiotics or fermented foods. Kombucha, kefir, yoghurt, sauerkraut and probiotic capsules can worsen symptoms when bacteria are overgrowing in the small intestine.
Antibiotics improve your symptoms. This is one of the strongest signs. If you have felt temporarily better after a course of antibiotics, it may be because the bacterial load in the small intestine was reduced.
Other symptoms to consider
The following symptoms are worth considering in your case. While SIBO doesn’t cause every symptom, when combined and especially alongside gut symptoms, they may provide important clues.
- Rosacea and skin conditions such as psoriasis, eczema and facial acne.
- Difficulty sleeping and chronic fatigue
- Anaemia or iron deficiency
- Nutrient deficiencies
- Headaches
- Increased heart rate
- Dizziness
- Hormonal imbalances
- Hair loss
- Autoimmune issues (rheumatoid arthritis, hypothyroidism)
- Recurring vaginal infections.
These ‘extra-intestinal’ symptoms can come from several different mechanisms, making SIBO feel more like a whole-body condition than exclusively a digestive condition. These include:
- Nutrient malabsorption leading to deficiencies
- Inflammatory responses to overgrowth of bacteria
- Disruption of normal gut-brain function
- Fermentation gases influencing the nervous system and circulation.
- Blood sugar fluctuations from disruption of normal digestion
- Impaired sleep from chronic pain.
How do I get help for SIBO?
If these symptoms resonate with you and if you notice these pattern clues it may be worth exploring whether SIBO is part of your gut picture.
At Tree of Life Nutrition, our gut specialist dietitians can help determine whether SIBO testing is appropriate, arrange the breath test, interpret results, and guide you through a treatment plan that supports long-term gut recovery.
You don’t have to keep guessing. Understanding the underlying cause of your symptoms can be the first step toward meaningful, lasting relief.
DISCLAIMER:
The content in this article is not intended as medical advice. It is also of a general nature and is not tailored to your individual circumstances. If you are experiencing significant digestive symptoms, a 1:1 consultation is always the best approach. Please contact our clinic to discuss your unique situation and our tailored and individualised IBS protocol.
