Why it works?

Laxatives can be helpful with constipation. Symptoms of constipation are straining while having a bowel movement, passing hard stool, feeling obstructed or the sensation of incomplete evacuation.

Constipation may be temporary due to an unhealthy lifestyle or poor dietary intake.

There are some lifestyle modifications one should try before using laxatives. These include:

  • Increasing fluid intake to at least 8 cups a day to keep stool soft and easy to pass. You may need more if you are exercising or during hot weather. Please consult your doctor regarding an amount of fluid allowed if you have heart disease or kidney disease.
  • Stay away from alcohol as it contains diuretics that may cause excessive urinary loss of water
  • Stay away from caffeinated drinks such as coffee, tea and coke as they contain diuretics as well
  • Increase intake of dietary fibre, from sources such as vegetables, fruits or whole grain.

When should laxatives be needed? 

One can consider laxatives if the symptom persists despite lifestyle modifications. One should consider a medical consultation if the onset of constipation is new and there is a recent change in bowel habit.

What are the types of laxatives available? 

There are 6 types of laxatives. Each has different mechanisms and possible side effects.

1. Bulking Agents (Fibers)

  • They are used in patients who have normal and slow transit constipation where dietary intake of fibre may not be adequate.
  • They work by increasing water content and bulk of stool, which helps to move it quickly through colon.
  • Side effects: They may cause bloatedness or abdominal cramping.
  • Examples of bulking agents include psyllium, ispaghula (Fybogel) .

2. Lubricant laxative

  • Used to make stool less viscous and easier to pass
  • Side effects: Over a longer period, mineral oil can absorb fat-soluble vitamins from intestine and may decrease certain medication. Hence, it is only used for short-term relief for constipation.
  • An example of a lubricant laxative is mineral oil.

3. Stool softeners

  • These increase the water content of the stool to keep stool soft and easier to pass.
  • Stool softeners might take a week or longer to work.
  • Generally, it may be recommended in patients who are recovering from surgery,
  • women who just gave birth or individuals with haemorrhoids.
  • An example of a stool softener is docusate sodium (Dulcolax)

4. Osmotic laxatives

  • It encourages bowel movements by drawing water into the bowel to soft water
  • Some of these laxatives may cause electrolytes imbalances as they draw out nutrients and other contents with water.
  • It is usually used for bowel preparation for colonoscopy or before surgery.
  • An example of osmotic laxatives includes polyethylene glycol (PEG), sodium phosphate and lactulose.
  • Lactulose can be used in chronic constipation but has a slower onset of action

5. Stimulant laxatives

  • These stimulate the intestine and thereby increases colonic transit time.
  • It should not be used on a daily basis as it may cause laxative dependency
  • Potential side effects include cramping and diarrhea
  • Example of stimulant laxatives are senokot (Senna), Dulcolax, bisacodyl

6. Enema

  • It usually involves inserting stimulant or osmotic laxatives directly into the rectum or anus.
  • It may be preferred occasionally to relieve severe constipation or to empty the bowel prior to surgery.
  • Example of enema includes fleet enema, bisacodyl suppository.

Take home messages:

  • Use fibre supplementation first, prior to using long-term laxatives
  • Drink plenty and stay hydrated when using laxatives
  • Avoid stimulant laxatives if possible.
  • If you continue to have problems with constipation, please consult your doctor. Constipation may be a warning sign of a more serious problem such as hypothyroidism, colon cancer or diabetes, amongst others.