Diarrhoea persistent causes in adults

Overview

Diarrhoea that lasts more than a few weeks is called persistent diarrhoea. It means having loose or watery stools (poo) regularly for 2 to 4 weeks or longer. In adults, this can be a sign of an infection or a long-term condition affecting the digestive system.

Yes, many adults experience a bout of diarrhoea that lasts longer than usual. It is common enough that doctors see it often in general practice.

It can affect any adult, but those with weakened immune systems, recent travel, or conditions like IBS are more likely to have persistent symptoms.

Symptoms

Common symptoms

• Frequent loose or watery stools
• Urgent need to use the bathroom
• Abdominal cramps or pain
• Bloating or gas
• Feeling tired or weak

Symptoms in children

• This article is about adults. For children, persistent diarrhoea can lead to dehydration quickly and needs a doctor’s attention.

Symptoms in older adults

• Older adults may get dehydrated more easily, even with mild diarrhoea.
• They might also have confusion or dizziness as a sign of dehydration.
• Symptoms like weight loss or loss of appetite may be more noticeable.

Causes

Main causes

• Infections from bacteria, viruses, or parasites (often from contaminated food or water)
• Irritable bowel syndrome (IBS) – a common condition affecting the bowel
• Inflammatory bowel disease (IBD) – such as Crohn’s disease or ulcerative colitis
• Food intolerances (like lactose intolerance or gluten sensitivity)
• Side effects of some medications (like antibiotics or certain diabetes drugs)
• Problems absorbing nutrients (malabsorption) – for example, after gallbladder removal

Risk factors

• Recent travel to areas with poor sanitation
• Weakened immune system (from illness or medicines)
• Having a chronic digestive condition like Crohn’s or IBS
• Taking antibiotics or other drugs that affect the gut
• Diet high in artificial sweeteners or dairy products if lactose intolerant

When to see a doctor

See a doctor urgently if:

• If you have any emergency symptoms listed above, call your local emergency number right away.
• See a doctor the same day if you have blood in your stool, severe pain, fever, or cannot keep fluids down.

Book a routine appointment if:

• If diarrhoea lasts more than 2 weeks, even if it is mild, make an appointment with your general practitioner (GP).
• Also see a doctor if you have unexplained weight loss, symptoms that wake you at night, or a family history of bowel disease.

Diagnosis

Your doctor will ask about your symptoms, travel history, diet, and medicines you are taking. They may feel your belly and check for signs of dehydration.

Tests that may be done

• Stool test – to look for infection or blood
• Blood test – to check for inflammation, anaemia, or celiac disease
• Breath test – for lactose intolerance or bacterial overgrowth
• Flexible sigmoidoscopy or colonoscopy – a thin tube with a camera to look inside your bowel

What to expect at your appointment

Your doctor will explain what tests you need and why. Most tests are quick and not painful. If a colonoscopy is needed, you will get instructions to clean your bowel beforehand. You will be offered sedation to keep you comfortable.

Treatment

Treatment depends on the cause. The goal is to stop the diarrhoea, prevent dehydration, and treat any underlying condition.

Self-care at home

• Drink plenty of clear fluids (water, clear soup) to avoid dehydration
• Eat small, bland meals – like plain rice, bananas, toast, or applesauce
• Avoid dairy, fatty foods, caffeine, and alcohol until symptoms improve
• Try a temporary lactose-free diet if you suspect lactose intolerance
• Rest – your body needs energy to fight infection or heal

Medical treatments

For dehydration, doctors may recommend oral rehydration salts (dissolved in water) to replace lost fluids and minerals. For infections, they will decide if antibiotics or other anti-infective medicines are needed. For IBS or IBD, treatments focus on managing the condition with diet, stress reduction, and medicines that help control bowel movements. Do not take any anti-diarrhoea medicines without talking to your doctor first, as they can make some infections worse.

When is surgery considered?

Surgery is rarely needed for persistent diarrhoea. It may be considered only if a condition like inflammatory bowel disease causes a blockage or severe damage to the bowel. Your doctor will discuss this if it applies to you.

Living with this condition

Living with persistent diarrhoea can be tiring and stressful. Keep a diary of your symptoms, foods, and activities to help you and your doctor find triggers. Plan your day around easy access to a toilet when needed.

Lifestyle tips

• Eat small, frequent meals rather than large ones
• Stay well hydrated between meals
• Identify and avoid foods that trigger your symptoms (like spicy foods, high-fibre foods, or dairy)
• Practice good stress management – deep breathing, gentle exercise, or talking to someone

Diet and exercise

A balanced diet is important. If you have malabsorption, a dietitian can help you get the nutrients you need. Gentle exercise like walking can help digestion, but avoid strenuous activity during flare-ups.

Mental health and emotional wellbeing

Persistent diarrhoea can cause anxiety, embarrassment, and social withdrawal. You may worry about having accidents. This is normal. Talk to your doctor about your feelings. They can refer you to a counsellor or support group.

Prevention

Some types of persistent diarrhoea can be prevented with good hygiene and safe food practices. Wash hands before eating and after using the toilet. When travelling, drink bottled water and avoid undercooked food.

Vaccines

Not usually needed for adults. Rotavirus vaccine is given to infants to prevent a common cause of severe diarrhoea, but it is not routinely offered to adults.

Screening programmes

There is no standard screening test for persistent diarrhoea. Routine bowel cancer screening (like the faecal immunochemical test, FIT) may be offered to adults over a certain age in some countries. This checks for hidden blood in stool but is not specifically for diarrhoea.

Complications

If left untreated

• Dehydration – which can lead to kidney problems or low blood pressure
• Malnutrition – not getting enough nutrients from food
• Weight loss and muscle wasting
• Worsening of underlying conditions like IBD or IBS

Long-term outlook

For most adults, persistent diarrhoea improves once the cause is found and treated. Even long-term conditions like IBS or IBD can be managed well with the right care. You can expect to feel better and return to normal activities. Work with your healthcare team for the best outcome.

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