Bulking agents

These laxatives act by absorbing water and swelling up, which softens the stool and stimulates the squeezing action of the colon. This type of laxative may take 24-36 hours to work and so is not considered to be suitable for fast treatment of acute constipation. They also may not be effective in cases where the constipation is caused by a disturbance of the nerves in the intestines or by any problem in the glands.

Bulking agents are usually difficult to swallow and so, to work properly, you will need to drink plenty of liquids. This may be a concern for older people/seniors with a reduced feeling for thirst or those with a restricted fluid intake. Bulk-forming laxatives, especially insoluble fibre products, have also been known to cause flatulence, which can be a source of embarrassment for users. People with diabetes who are on a restricted diet may need to take into account the carbohydrates in the laxative itself.

A recent review has shown that bulk forming laxatives can even be counter-productive in severe chronic constipation, as increased dietary fibre intake can make symptoms worse. If you have any concerns, you should seek the advice of your healthcare professional, who will be able to advice you on what the best treatment is.

Osmotic laxatives | Plat-derived purgatives | Synthetic stimulants