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Laxatives for constipation


Laxatives are medicines that increase the frequency and ease of passing stool. Laxatives are available as:

  • Tablets or capsules
  • Sachets of powder
  • Suppositories

There are several type of laxatives and each one has a different effect on the digestive system. Most of laxatives are available as over-the-counter (OTC) for the relief of mild and occasional constipation. However, if the constipation becomes moderate to severe or does not respond to OTC products, a doctor should be consulted.

Type of laxatives

In general, laxatives can be classified into four main categories:

  1. Bulk forming laxatives
  2. Stimulant laxatives
  3. Osmotic laxatives
  4. Stool softeners

How they work

  1. Bulk forming laxatives

    Bulk forming laxatives relieve constipation by forming soft, bulky stool, and promoting the intestinal muscles contraction for easier passage of stools. They are generally considered the safest one and are of particular value in patients with small hard stools. Nevertheless, they do not work until after a few days of consumption and patients need to take plenty of fluids. Examples of bulk laxatives include bran, ispaghula, methylcellulose, psyllium and sterculia.

  2. Stimulant laxatives

    Stimulant laxatives speed up the bowel movement by stimulating the contraction of intestinal muscles. Their onset of action (about 6-12 hours) are more rapid than bulk laxatives, and are usually given at night to help produce a bowel movement the following morning. Examples of stimulant laxatives are bisacodyl, senna and sodium picosulfate.

  3. Osmotic laxatives

    Osmotic laxatives soften the stools by increasing the amount of water in the small intestine and colon, which increase size and pliability of stools. Examples include macrogols, saline laxatives such as magnesium hydroxide, and poorly absorbed sugars such as lactulose or sorbitol.

  4. Stool softeners

    Stool softeners add moisture to stools, and make them softer and easier to pass out of the body. They have added value for patients with haemorrhoids or anal fissures, or those in whom straining is potentially hazardous such as the elderly or those with existing cardiovascular disease. Docusate is one of the examples.

Side effect

Bulk forming laxatives
Stimulant laxatives
Osmotic laxatives
Stool softeners
  • Bloating and flatulence
  • Abdominal distension
  • Gastro-intestinal obstruction or impaction
  • Hypersensitivity
  • Abdominal cramp
  • Nausea and vomiting
  • Diarrhoea
  • Local irritation if suppository preparation is used
  • Tolerance
  • Abdominal pain
  • Bloating and flatulence
  • Nausea and vomiting
  • Abdominal cramp
  • Nausea
  • Skin rash


Laxatives should be kept in a cool and dry place. Unless specified on the label, medicines should not be stored in refrigerators. Furthermore, drugs should be kept properly in places unreachable by children to prevent accidental ingestion.

Before trying laxatives

In most cases of constipation, simple changes in the dietary and lifestyle can help in relieving the symptoms and managing constipation:

  • Eat a diet rich in fibre with whole grains, fruits, and vegetables
  • Stay hydrated – drink at least 6-8 glasses of water per day
  • Exercise regularly
  • Encourage positive toilet routine by having a regular toilet habit and spending at least 10 minutes in the toilet to make sure you have passed as many stools as possible.

However, in the case where the constipation is caused by the side effect of a drug or an underlying medical condition, it is better to seek medical advice to see whether changing to a less constipating drug or treating the underlying medical condition is possible.

Misuse of laxative

Today, many people use laxatives to lose their weight as to keep up with society’s image of beauty. Some are even using laxatives to lose weight as a quick solution instead of choosing a long-term healthy weight loss programme by exercising and eating healthy. However, many people are unaware that misuse of laxative can lead to severe medical complication and sometimes causing life-treathening conditions.

Frequent bowel movements caused by laxatives tend to give people a false sense of being cleansed. While some quick weight loss effect may be obtained, most of the pounds shed are from loss of water. Once the laxative use is stopped, most, if not all, the weight lost will be regained fairly quickly.

Laxatives are not the ideal way to permanently lose weight as they can be very unhealthy for the body and can create many unpleasant side effects. With laxative use, some people do not realize that they are also cleansing themselves of important nutrients and calories, affecting their natural fat absorption, and upsetting their electrolyte levels.


  1. NHS Choices. (2012) Laxatives. Available from http://www.nhs.uk/ conditions/ laxatives/Pages/Introduction.aspx
  2. Chuncha P.J. (2011) Laxatives for constipation. Available from http://www. medicinenet.com/laxatives_for_constipation/article.htm
Last Reviewed : 11 August 2014
Writer : Nurhazwani bt. Mohd Noor
Accreditor : Hazlinda Nazli bt. Naem