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When to worry about diarrhoea

It may not be dinner party conversation, but most of us have had tummy trouble at some point. Having diarrhoea, vomiting and colicky tummy pain together often signifies food poisoning or a bug, but if it goes on, you need it looked into. Short-term diarrhoea due to a tummy bug is common, but see your doctor if it persists for over a week. Likewise, always see your doctor if you've recently travelled somewhere exotic (outside Western Europe, the USA or Australasia), if you have blood in the diarrhoea or vomit, or if you have other long-term health conditions.

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What 'chronic' and 'diarrhoea' mean in medicine

My patients often use the word 'chronic' when they mean 'dreadful' ('I've been up all night with chronic stomach ache') but in medical terms it's used to mean long-term. But how long 'long-term' is, is a moveable feast.

As far as diarrhoea is concerned, some doctors say it's chronic if it's gone on for more than two weeks, and some say four weeks. One study suggested that one in 20 people get diarrhoea lasting at least four weeks in any year. Of course, the next question is what doctors mean by 'diarrhoea'. Officially, opening your bowels more than three times a day, with loose or liquid poos, is diarrhoea - but with some tummy bugs and other conditions, going a dozen times a day is common.

Some common causes of diarrhoea

Irritable bowel syndrome (IBS), commonly causes diarrhoea or constipation, or a mix of the two along with tummy pain (often eased by opening your bowels or passing wind) and bloating. However, it rarely starts over the age of 40 and you should never assume this is the cause. If it is diagnosed by your doctor, diet and lifestyle changes (including regular exercise and managing stress), along with tablets, can help. Doctors used to recommend a high-fibre diet, but it's now recognised that this can make diarrhoea worse.

Coeliac disease is an autoimmune disease - where your own immune system attacks part of your body, in this case the small bowel. It affects about one in 100 people, and while it can be diagnosed at any age, the most common time to be diagnosed is in your 50s or 60s. Your body reacts to gluten, found mostly in wheat, barley and rye.

Along with diarrhoea, bloating and wind, coeliac can stop your absorbing vitamins and nutrients and can lead to anaemia and tiredness. Weight loss and mouth ulcers sometimes happen too. These days, you can usually be diagnosed with a blood test, although you may need a biopsy of your small bowel in addition. Treatment involves avoiding all food containing gluten, for life - fortunately there are lots of options in the shops.

These days, many people avoid gluten - either because they've been told they are 'gluten-intolerant' or because they get symptoms like wind and bloating after eating gluten. If you are getting severe symptoms, it' important to check this out with your GP. If you don't have coeliac disease, you may want to cut down on gluten to avoid symptoms, but it won't do you any physical damage if you do eat small amounts. If, on the other hand, you're diagnosed with coeliac disease, it's essential to avoid even the smallest exposure to gluten for life.

Inflammatory bowel disease includes ulcerative colitis, which affects your colon (large bowel), and Crohn's disease, which can affect your large and small bowel. Both start most commonly in teenagers and young adults, but there is another 'peak' in new cases in people in their 50s-70s. Along with chronic diarrhoea, you may also have bleeding from the back passage, colicky tummy pain, needing to rush to the loo, fever, weight loss and tiredness. If your doctor suspects either of these conditions, they will want to do blood tests and probably ask for a sample of your poo to check for 'faecal calprotectin' - if this is positive, you will need to be referred to a hospital specialist.

An overactive thyroid gland makes your body tick over more quickly. Symptoms include diarrhoea, weight loss, feeling hot and trembling.

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Messy medicines

The range of medicines that can cause diarrhoea is endless. Common culprits include metformin (for type 2 diabetes), antibiotics, laxatives (amazing how often patients don't make the connection!), medicines for indigestion, anti-inflammatory painkillers and chemotherapy. If you've recently started a new medicine, speak with your pharmacist about whether this might be the cause. Don't stop medicines without medical advice, though - side effects like diarrhoea often settle within a few weeks and your doctor can advise on whether an alternative might be better.

Don't panic, but beware

It's important to remember that in most cases, diarrhoea doesn't mean bowel cancer, sometimes called colon cancer. However, it's something your doctor may consider, especially if you're over 50 or also have unexplained bleeding from your bottom, or have lost weight or been off your food.

If bowel cancer runs in your family, you may be at increased risk, and some people are eligible for regular colonoscopies to check for early changes which might become cancerous if left untreated. Do check with your GP. If you have bleeding from your back passage, always see your doctor. It's usually down to piles or another non-sinister cause, but better safe than sorry.

With thanks to 'My Weekly' magazine where this article was originally published.

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The information on this page is peer reviewed by qualified clinicians.

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