SIBO overview

Overview

SIBO stands for Small Intestinal Bacterial Overgrowth. It is a condition where there are too many bacteria in the small intestine. Normally, the small intestine has few bacteria, but in SIBO, they grow in numbers that can cause digestive problems.

SIBO is not extremely common, but it is seen in people with certain digestive disorders or those who have had abdominal surgery. It may affect up to 15% of people with IBS.

SIBO can affect anyone, but it is more common in adults, especially those over 60. It also occurs more often in people with conditions that slow gut movement, such as diabetes or Parkinson's disease.

Symptoms

Common symptoms

• Bloating after meals
• Excessive gas
• Stomach cramps or pain
• Diarrhea or loose stools
• Fatigue
• Feeling full quickly when eating

Symptoms in children

• Poor weight gain or weight loss
• Constant stomach ache
• Diarrhea that won't go away
• Signs of malnutrition, like lack of energy or slow growth

Symptoms in older adults

• Bloating and gas that are often mistaken for normal aging
• Unintended weight loss
• Low energy or weakness
• Changes in bowel habits

Causes

Main causes

• Slow movement of food through the small intestine, which allows bacteria to grow too much
• Physical problems in the gut, like scar tissue or a short bowel from surgery
• Low stomach acid, which normally kills many bacteria
• Immune system problems that let bacteria grow unchecked

Risk factors

• Getting older
• Having Irritable Bowel Syndrome (IBS)
• Diabetes that affects gut nerves
• Crohn's disease or other inflammatory bowel conditions
• Past abdominal surgery
• Using acid-reducing medicines for a long time

When to see a doctor

See a doctor urgently if:

• If you have severe stomach pain or vomiting and cannot pass stool or gas

Book a routine appointment if:

• If bloating, gas, or diarrhea does not improve after a few weeks of simple changes
• If you have unexplained weight loss or constant fatigue

Diagnosis

Doctors usually diagnose SIBO using a breath test or sometimes by taking a sample from your small intestine during an endoscopy.

Tests that may be done

• Lactulose or glucose breath test (you drink a sugar solution and breathe into a device at intervals)
• Small intestinal aspirate and culture (a tube is passed through the mouth to take fluid from the small intestine)

What to expect at your appointment

For a breath test, you will need to follow a special diet for 24 hours beforehand. The test is painless. During an endoscopy, you will be given a sedative and the doctor passes a thin tube down your throat – it feels uncomfortable but is not painful.

Treatment

Treatment for SIBO usually involves a course of antibiotics to reduce the bacteria, followed by diet changes to prevent them from coming back. Your doctor will help create a plan just for you.

Self-care at home

• Eat smaller, more frequent meals
• Avoid foods that are high in fermentable carbohydrates (like beans, onions, and certain fruits) – ask your doctor about a low FODMAP diet
• Stay well hydrated
• Manage stress, as it can worsen symptoms

Medical treatments

Doctors prescribe antibiotics that target the bacteria in the small intestine. Treatment usually lasts 7 to 14 days. Some people need more than one course. Antibiotics are chosen based on your symptoms and breath test results. Do not take any antibiotics without a prescription.

When is surgery considered?

Surgery is rarely needed for SIBO. It may be considered if there is a physical blockage or a structural problem in the intestine that can be fixed.

Living with this condition

Living with SIBO means paying attention to what you eat and how you feel. Many people learn which foods trigger their symptoms and avoid them. You may need to plan meals ahead to stay on track.

Lifestyle tips

• Keep a food diary to spot triggers
• Eat slowly and chew food well
• Stay active – gentle exercise like walking can help digestion
• Get enough sleep to support your immune system

Diet and exercise

A low FODMAP diet is often recommended, but it should be done with guidance from a dietitian. Exercise helps keep the gut moving and can reduce stress. Start with low-impact activities like walking or yoga.

Mental health and emotional wellbeing

Having a chronic gut problem can feel frustrating and embarrassing. It is normal to feel anxious or down about your symptoms. Talking to a doctor or a counsellor can help.

Prevention

There is no sure way to prevent SIBO, but you can lower your risk by managing underlying conditions like diabetes or IBS, and by avoiding long-term overuse of acid-reducing medicines.

Complications

If left untreated

• Malnutrition – your body may not get enough vitamins and minerals
• Weight loss
• Vitamin B12 deficiency, which can cause anaemia and nerve problems
• Damage to the lining of the small intestine

Long-term outlook

With proper treatment, most people with SIBO feel much better. The condition often clears up, but it can come back. Working closely with your doctor and making healthy lifestyle changes can help keep it under control.

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