Preparing for colonoscopy
Informed by recognized medical guidance
Overview
A colonoscopy is a procedure that lets a doctor look inside your large bowel (colon) using a thin, flexible tube with a camera. Preparing for it means cleaning out your bowel so the doctor can see clearly.
Key facts
- You need to follow a special diet and take a bowel-cleansing solution.
- You may need to stop certain medications beforehand.
- The preparation usually starts a few days before the test and causes diarrhoea.
Yes, colonoscopy is a common procedure, often done for screening or to investigate bowel symptoms.
People of all ages may need a colonoscopy, but it is most often recommended for adults over 50 or those with bowel symptoms.
Symptoms
- Chest pain
- Difficulty breathing
- Severe allergic reaction (rash, swelling, trouble swallowing)
- ⚠Severe abdominal pain during preparation
- ⚠High fever
- ⚠Unable to pass stool or gas with severe pain
Common symptoms
- Blood in stool
- Unexplained change in bowel habits
- Ongoing abdominal pain
- Unexplained weight loss
Symptoms in children
- Blood in stool
- Severe abdominal pain
- Change in bowel habits
Symptoms in older adults
- Blood in stool
- Change in bowel habits
- Unexplained anaemia
Causes
Main causes
- Screening for bowel cancer
- Investigating bowel symptoms like blood or pain
- Monitoring conditions like Crohn's disease or ulcerative colitis
Risk factors
- Age over 50
- Family history of bowel cancer
- Personal history of polyps or inflammatory bowel disease
When to see a doctor
See a doctor urgently if:
- If you have severe abdominal pain during preparation
- If you cannot drink the prep solution due to vomiting
- If you have a high fever
Book a routine appointment if:
- If you have questions about your diet or medications before the colonoscopy
- If you need to reschedule because of illness
Diagnosis
A colonoscopy allows the doctor to visually examine the inside of your colon and take tissue samples (biopsies) if needed.
Tests that may be done
- Colonoscopy itself
- Biopsy of any abnormal tissue
What to expect at your appointment
You will be given medication to help you relax. The procedure takes about 30 minutes. You need someone to take you home after.
Treatment
Preparation involves cleaning your bowel so the doctor can see clearly. This typically requires a special diet and a bowel-cleansing solution.
Self-care at home
- Follow your doctor's instructions on what to eat and drink
- Drink plenty of clear fluids as advised
- Avoid red or purple coloured drinks or foods
- Arrange for someone to drive you home
Medical treatments
Your doctor will prescribe a bowel-cleansing solution. You will take it in divided doses, usually the day before and the day of the procedure. It will cause diarrhoea to empty your colon. You may also need to adjust your regular medicines, such as blood thinners or diabetes medications, as directed by your doctor. Do not stop any medication without consulting your doctor.
When is surgery considered?
Colonoscopy itself is not surgery, but if polyps are found and removed, that is done during the procedure. If a large polyp or cancer is found, additional surgery may be needed later.
Living with this condition
After your colonoscopy, you may feel a little bloated or have mild cramps. You can usually return to normal activities the next day.
Lifestyle tips
- Eat a balanced diet with plenty of fibre
- Stay hydrated
- Follow your doctor's advice on bowel screening intervals
Diet and exercise
A diet rich in fruits, vegetables, and whole grains supports bowel health. Regular exercise also helps maintain a healthy digestive system.
Mental health and emotional wellbeing
Waiting for results of a colonoscopy can be stressful. It is normal to feel anxious. Talking to your doctor or a counsellor can help.
Prevention
You cannot prevent all conditions that require a colonoscopy, but a healthy lifestyle may reduce your risk of bowel cancer.
Screening programmes
Screening colonoscopy is recommended for people at average risk starting at age 50, or earlier if you have a family history. Talk to your doctor about when to start.
Complications
If left untreated
- Poor bowel preparation can lead to an incomplete procedure
- You may need to repeat the colonoscopy
Long-term outlook
Most colonoscopies are completed successfully. Following the prep instructions carefully gives you the best chance of a clear exam.
Find support
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Always verify with your doctor
Health guidelines vary by country and region. The information in this article is based on international clinical guidelines but may not reflect the specific guidelines, medications, or practices in your country. Always discuss your health concerns with your own doctor or healthcare provider, and refer to your local national health guidelines where available.
Important notice This information is for educational purposes only. It does not replace professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider about your specific situation. If you are experiencing a medical emergency, call your local emergency services immediately.
Related conditions
Sources and guidance
This article is educational and is prepared with reference to recognized health information and clinical guidance sources where available. Specific source links may vary by topic.
Last updated: July 16, 2026
Educational note: This information is for education only and is not a diagnosis.
Use it to support, not replace, advice from a licensed clinician.
If symptoms are severe, worsening, or urgent, call your local emergency number or seek emergency care.
Guidance may differ by country or region. Confirm local recommendations with a qualified healthcare provider.