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Psyllium Husk vs. Stimulant Laxative (Bisacodyl)

Guest Author 7 years ago

In her final year studying at the College of Naturopathic Medicine, Cristina Perrone wrote an essay which compared Bisacodyl with Psyllium Husk. Below is a summary of her essay, including how Bisacodyl works and how it stacks up to a natural alternative like Psyllium Husk.


Bisacodyl is a stimulant-type laxative used to treat constipation,[1] and is often used to empty the bowels in patients before they go in for surgery, colonoscopies, x-rays and other medical procedures which involve the digestive system.

Like other stimulant laxatives, Bisacodyl gathers water and electrolytes in the colon which softens the stool and makes it easier to pass (Read more about laxatives). Bisacodyl might also promote the production of prostaglandins, which can help with regulating bowel movements. Put simply, Bisacodyl works by making your bowel muscles contract more often and with more force.

Boehringer Ingelheim Pharmaceuticals ran a study in 2007[2] to see how well Bisacodyl worked over a 4 week period. The study was a randomised, double-blind, placebo-controlled parallel group study (that basically means it’s very thorough). The study showed that 50% of the participants taking Bisacodyl were happy with the outcome, compared to just 20% of the placebo control group. However, the study also showed a number of side effects related to taking Bisacodyl, including diarrhoea and abdominal pain. Over 50% of participants suffered from diarrhoea and almost a quarter suffered from abdominal pain.

A further study published in the Journal of Clinical Gastroenterology and Hepatology shows that in a 4 week treatment period almost 80% of patients taking Bisacodyl saw an improvement, whilst less than 50% of patients taking a placebo noticed a difference. Much like the other study, a larger portion of participants taking Bisacodyl suffered from diarrhoea when compared to the placebo group (53.4% versus 1.7%).

Both studies show that Bisacodyl is effective, but you mustn’t forget to take into consideration the limitations of the study, which in both instances had a relatively small number of participants over a relatively short period of time.

The British National Formulary[3] explains that excessive use of a stimulant laxative like Bisacodyl can cause diarrhoea and related side effects like hypokalaemia (below normal level of potassium in the blood). Some of the side effects can be avoided if you take the drug correctly. Bisacodyl should not be taken with a meal and it shouldn’t be crushed, chewed or broken because this damages the enteric coating which can cause abdominal discomfort.

Psyllium Husk

A natural alternative to laxative drugs is Psyllium husk. Psyllium comes from the seed of the Plantago ovago plant, which is natively found in Iran and India. Psyllium husk swells when it comes into contact with water, which helps to keep faeces hydrated and soft as they pass through the gut. Psyllium can help relieve both constipation and diarrhoea, and is used to treat irritable bowel syndrome, haemorrhoids and other intestinal problems.[4]

Although no side effects have been shown in relation to taking Psyllium, you need to remember to increase the amount of water you’re drinking. You should bear in mind to drink plenty of water whilst taking Psyllium (between 6 and 8 glasses a day) because without adequate lubrication the Psyllium husk could absorb too much water and make matters worse.

Comparing Psyllium Husk and Bisacodyl

A scientific study by Tack and Müller–Lissner focusing on current pharmacological approaches to chronic constipation highlights the different modes of action of a number of laxatives, including Psyllium husk and Bisacodyl. In particular they explain how Psyllium husk bulks up faeces and reduces consistency whilst Bisacodyl increases peristalsis activity and stops the colon from absorbing water. Moreover, the study suggests that most laxatives are relatively effective when compared to a placebo, but there is little evidence to distinguish between different types of laxatives. Most interestingly, the overall efficacy of Psyllium was registered as ‘fair’, whilst Bisacodyl was only marked as ‘poor’.[5]

Another study aimed at comparing different laxative treatments has also shown how Psyllium was an effective treatment for simple constipation, and was associated with better stool consistency and less side effects when compared to other laxatives.[6]

At the moment there is no evidence that using Bisacodyl and Psyllium husk together is either beneficial or damaging. Extensive research on this issue shows that no studies have been on this topic. However, it’s fair to assume that the bulking action of Psyllium could counteract any potential diarrhoea side effects from taking Bisacodyl. But, as mentioned before, there aren’t any trials on this and it remains a hypothesis maybe worth investigating.


In conclusion, Bisacodyl and Psyllium husk are laxatives proven to successfully treat constipation. At the moment there are no studies exploring how these two laxatives interact with each other, however it should be noted that taking Bisacodyl should be limited to a short period of time, or used intermittently.

saladFurthermore, when Psyllium husk is taken alongside a healthy diet and increased water intake, it can be taken for longer periods, or even indefinitely, if there are no new medical conditions or interactions with other drugs.

Find out more about natural remedies other than Psyllium husk.

About Cristina

Cristina is currently completing her training as a Naturopathic Nutritionist at the College of Naturopathic Medicine in London. She is an advocate of vegan cuisine and enjoys sharing her passion for fermented food with friends and colleagues.

References & Footnotes

[1] MHRA (2010) Summary of product characteristics: Bisacodyl

[2] Boehringer Ingelheim Pharmaceuticals (2007) Dulcolax vs Placebo in Functional Constipation

[3] British National Formulary (2008), BNF 56th edn. Biggleswade, RPS Publishing

[4] University of Maryland Medical Center (2011) Psyllium

[5] Tack, J. and Müller–Lissner, S (2009) ‘Treatment of Chronic Constipation: Current Pharmacologic Approaches and Future Directions’, Clinical Gastroenterology and Hepatology, 7 (5), pp. 502-508. 

[6] Dettmar, P.W. and Sykes, J (1998), ‘A multi-centre, general practice comparison of ispaghula husk with lactulose and other laxatives in the treatment of simple constipation’, Current Medical Research and Opinion, 14 (4), pp. 227-233.

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