Can preparation for a colonoscopy cause high blood pressure? 

Can preparation for a colonoscopy cause high blood pressure? 

Preparations for colonoscopy do not necessarily cause high blood pressure or affect your heart rate. The most common preparation starts with dietary changes. 

However, studies have indicated that bowel preps for colonoscopy can either cause high blood pressure or low blood pressure in some individuals. 

These people are usually associated with other comorbidities like renal insufficiency, hypertension, old age, etc. If we talk about a normal and healthy individual, there isn’t any prominent effect on blood pressure to talk about. 

The main goal of colonoscopy preparation is to clean out the colon so that the doctor can get a clear view of the intestinal lining. This is usually done by consuming a prescribed bowel-cleansing solution, which may be in the form of a liquid or pills. The solution helps to flush out the stool from the colon. (1,2)

Before the colonoscopy, you may be asked to follow specific dietary restrictions. This often includes avoiding solid foods and consuming only clear liquids, such as water, broth, clear juices, and gelatin. It is important to follow these instructions carefully to ensure effective bowel cleansing.

Factors that may contribute to temporary blood pressure changes during colonoscopy preparations

Some factors may affect your blood pressure during colonoscopy preparations, including: (3)

Fluid and electrolyte imbalance

The preparation process for a colonoscopy often involves consuming a significant amount of laxatives or bowel-cleansing agents. These substances can cause fluid loss and electrolyte imbalances in the body, which can affect blood pressure regulation.


The colonoscopy preparation may require fasting or limiting fluid intake for a certain period. This can lead to temporary dehydration, which can potentially impact blood pressure levels.

Stress and anxiety

Many individuals may experience stress or anxiety before undergoing a colonoscopy. These emotional factors can trigger temporary increases in blood pressure.


Certain medications used during the preparation process or taken regularly by the individual may interact with blood pressure regulation mechanisms, leading to temporary changes in blood pressure.

Vasovagal response

Some people may have a vasovagal response, which is a reflex response of the nervous system that can cause a temporary drop in blood pressure. This response can be triggered by various factors, including anxiety, pain, or the sight of blood.

What to do if your blood pressure is going too high before a colonoscopy?

If you think your BP is going high because of the preps, discuss it with your healthcare provider. A colonoscopy is often delayed when your blood pressure is too high before the procedure. 

People who have been taking antihypertensives may suffer from low blood pressure during the prep for a colonoscopy. The best thing is to follow your doctor’s directions as he or she will guide you throughout the entire process.

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Parekh PJ, Oldfield EC 4th, Johnson DA. Bowel preparation for colonoscopy: what is best and necessary for quality? Curr Opin Gastroenterol. 2019 Jan;35(1):51-57. doi: 10.1097/MOG.0000000000000494. PMID: 30489414.


Millien VO, Mansour NM. Bowel Preparation for Colonoscopy in 2020: A Look at the Past, Present, and Future. Curr Gastroenterol Rep. 2020 May 6;22(6):28. doi: 10.1007/s11894-020-00764-4. PMID: 32377915.


Patel N, Kashyap S, Mori A. Bowel Preparation. 2023 Apr 17. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan–. PMID: 30570989.