The causes of chronic constipation are more varied and complex than most people realise — and laxatives don’t address a single one of them.
One in four Australians experiences constipation. Despite how common it is, most people are still reaching for laxatives rather than asking the question that actually matters: why is this happening?
Laxatives have their place — but they don’t address the underlying cause. And until the cause is identified and addressed, constipation tends to keep coming back.
As a naturopath with extensive experience in the causes of chronic constipation, I’ve spent years helping people get to the root of what’s really driving their bowel struggles. Here are the 10 most common causes I see in clinical practice — many of which are routinely missed.
What counts as chronic constipation — and what causes it?
Before diving in, it’s worth clarifying what constipation actually means clinically. Based on the Rome IV criteria — the gold standard framework used by gastroenterologists worldwide — chronic constipation involves two or more of the following for at least three months:
- Straining during more than 25% of bowel movements
- Lumpy or hard stools (Type 1 or 2 on the Bristol Stool Chart) in more than 25% of movements
- A sensation of incomplete emptying in more than 25% of movements
- Fewer than three spontaneous bowel movements per week
- Needing to use your fingers or apply perineal pressure to assist defecation
You can be constipated even if you go every day. Frequency alone doesn’t tell the whole story.
1. Poor diet and inadequate fibre
Fibre is the single most important dietary factor for bowel regularity — and most Australians aren’t getting enough. The recommended intake is 38g daily for men and 28g for women. The average Australian adult consumes just 20.7g per day.
Both types of fibre matter. Soluble fibre (found in oats, kiwifruit, legumes, and root vegetables) dissolves in water and forms a gel that slows digestion and feeds beneficial bacteria. Insoluble fibre (found in wholegrains, flaxseeds, and berries) adds bulk and promotes peristalsis.
Some of the best-evidenced food inclusions for constipation relief include kiwifruit, dragon fruit, flaxseeds, oats, and berries. A gradual increase of around 5g of fibre per day is recommended to avoid bloating and discomfort during the transition.
2. Dehydration
Water is essential for keeping stool soft and easy to pass. Without adequate fluid intake, your colon absorbs more water from waste as it moves through — making stool harder, drier, and more difficult to eliminate.
Aim for 2–3 litres of filtered water daily. Constipation prevalence increases with lower water intake, and increasing hydration is one of the simplest first steps — particularly if you’re also increasing fibre, as fibre requires water to work effectively.
3. Sedentary lifestyle
Physical movement directly stimulates gut motility. Research shows a clear positive correlation between regular physical activity and bowel movement frequency. Even moderate daily movement — walking, yoga, swimming — can make a meaningful difference to transit time.
If you spend most of your day sitting, your gut knows it. Building movement into your daily routine is one of the foundational strategies I recommend to every client with constipation.
4. SIBO — a hidden cause of chronic constipation
Small intestinal bacterial overgrowth (SIBO) is one of the most commonly missed drivers of chronic constipation — and one of the most important to identify.
Methane-producing organisms in the small intestine, particularly Methanobrevibacter smithii, slow gut motility and transit time. Methane gas itself has been shown to directly slow intestinal contractions — meaning the more methane present, the harder it becomes to move things through. It also increases contractile activity in a backward direction, further impeding elimination.
SIBO requires specific testing — a lactulose or fructose breath test — and targeted treatment. If your constipation hasn’t responded to dietary and lifestyle changes, SIBO is worth investigating. As a SIBO naturopath, I test for this routinely in clients with chronic constipation.
SIBO is one of the most overlooked causes of chronic constipation I see — and as a naturopath with extensive experience in chronic constipation, it’s one of the first things I investigate.
5. Gut microbiome dysbiosis
Your gut microbiome plays a direct role in bowel regularity. Research shows that people with chronic constipation have a distinctly different microbiome profile to those without — with reduced levels of butyrate-producing bacteria like Faecalibacterium prausnitzii and Lachnospiraceae, and elevated levels of methane-producing organisms.
Butyrate is the primary fuel source for the cells lining your gut wall. Lower butyrate means a less healthy gut lining, reduced motility signalling, and longer transit times. Short-chain fatty acid production — which drives peristalsis — is also reduced.
Microbiome testing can identify specific imbalances and guide targeted probiotic, prebiotic, and dietary interventions. This is something I assess in detail in my gut health consultations.
Gut microbiome dysbiosis is a frequently missed cause of chronic constipation and one I investigate in depth with every client.
6. Pelvic floor dysfunction
Pelvic floor dysfunction — sometimes called dyssynergic defecation or outlet obstruction — is a significant cause of chronic constipation, particularly in women, and one that requires specific assessment to identify.
Normal defecation requires coordinated relaxation of the pelvic floor muscles at the moment of evacuation. In pelvic floor dysfunction, these muscles contract instead of relaxing — creating a mechanical obstruction that makes elimination difficult or incomplete regardless of how well everything else is functioning.
Signs that pelvic floor dysfunction may be a factor include straining, a feeling of incomplete emptying, needing to use your fingers to assist evacuation, or pain during defecation. Referral to a pelvic floor physiotherapist is often an essential part of treatment — this is not something diet and supplements alone can fix.
7. Stress, trauma and the gut-brain connection
The gut and brain are in constant bidirectional communication via the gut-brain axis. Stress, anxiety, depression, and unresolved trauma all have a direct impact on gut motility — and constipation is frequently the result.
Stress can slow motility, increase pelvic floor tension, alter gut microbiota composition, and increase intestinal permeability. Research has also shown associations between chronic constipation and a history of physical or sexual abuse, stressful life events, and depression.
This doesn’t mean constipation is “in your head” — it means the nervous system is a legitimate and important driver that deserves attention alongside diet and lifestyle. Gut-directed hypnotherapy, cognitive behavioural therapy, and vagal nerve support are all evidence-based approaches worth considering.
8. Hormonal fluctuations
Hormones have a significant influence on gut motility — which is why constipation often worsens at particular points in the menstrual cycle, during pregnancy, and around perimenopause.
During pregnancy, progesterone relaxes smooth muscle throughout the body — including in the intestinal wall — slowing transit time. The growing uterus adds mechanical pressure. Around perimenopause, fluctuations in oestrogen and progesterone can disrupt bowel regularity in ways that are frequently attributed to other causes.
Oestrogen recycling via the gut is also relevant here — when transit is slow, used oestrogen that should be excreted gets reabsorbed, contributing to a hormonal imbalance that can then further affect gut function.
9. Medications
Many commonly prescribed and over-the-counter medications list constipation as a side effect, including:
- Opioid analgesics — opioids slow intestinal transit significantly; up to 90% of users experience constipation
- Antidepressants — particularly tricyclic antidepressants
- Antihistamines
- Antihypertensives
- Iron supplements — iron diglycinate is a form less likely to cause constipation
- Antipsychotics
- Chemotherapy agents
If you’ve noticed your constipation coinciding with starting a new medication, it’s worth discussing with your GP or specialist. There are often alternatives or adjunct strategies that can help.
10. Ignoring the urge to defecate
This one is simple but surprisingly significant. When you consistently suppress the urge to defecate — because you’re busy, not at home, or uncomfortable using public bathrooms — the rectum adapts. Over time, the normal defecation reflex weakens, stool sits longer in the colon (becoming harder and drier), and the urge becomes less frequent and less noticeable.
Responding promptly to the urge to defecate — particularly in the morning when the gastrocolic reflex is strongest — is one of the most important behavioural habits for long-term bowel health.
What to do next
If you’ve been dealing with the causes of chronic constipation going unidentified for a long time, there’s likely a specific driver — or combination of drivers — that hasn’t yet been found. The good news is that with the right investigation, most causes of chronic constipation are addressable.
Want to go deeper? My guide Get Things Moving covers all 10 of these root causes in detail — plus the specific foods with the strongest clinical evidence for constipation relief, foundational strategies you can start today, and clear guidance on when professional investigation is the right next step. Every recommendation is backed by peer-reviewed research. [Download your copy for $37 AUD]
As a naturopath with extensive experience in the causes of chronic constipation, I use microbiome testing, SIBO breath testing, and a thorough case history to identify exactly what’s driving your constipation — and build a plan around that.
You can also support your bowel daily with [BetterMe Tea] — my naturopath-formulated herbal tea designed to promote healthy gut function and ease of elimination.