Laxatives

Laxatives are used to help relieve constipation. Before taking any laxative you need to be sure that you really are constipated. Normal bowel movements vary from person to person. So, if you have cancer, you should always check with your doctor before taking any type of laxative.

If you have a colostomy or ileostomy you may not be able to take some types of laxatives. Your doctor will want to assess your constipation and the cause of your constipation before recommending the best treatment for you.

Remember - if you have constipation and vomiting, do not take laxatives without checking with your doctor first. If your bowel is blocked, they will do more harm than good.

You can buy many laxatives over the counter at the chemist, supermarket and health food store without a prescription from your doctor. Others need a doctor’s prescription. Laxatives come as

• Tablets, capsules or granules
• Foods, such as bran
• Syrups
• Powders that can be made into a drink by adding water or fruit juice
• An enema that you have into the back passage
• Suppositories that you have into the back passage

There are 3 types of laxatives

• Bulk forming laxatives
• Stimulant laxatives
• Osmotic laxatives

Bulk forming laxatives

These work by swelling up inside your bowel. This helps soften and increase the amount of stool, which encourages your bowels to move and push the stools out. This type of laxative can take a few days to work properly. Examples include

• Bran
• Fybogel
• Celevac
• Normacol

Stimulant laxatives

Stimulant laxatives work by speeding up bowel movement. They can take between 8 and 12 hours to work. Examples include

• Bisacodyl
• Docusate sodium
• Co-danthrusate (Normax) and co-danthramer
• Glycerol suppositiories
• Senna (Senakot)
• Syrup of figs

Osmotic laxatives

Osmotic laxatives work by drawing more water into your bowel. This makes your stools softer and easier to pass.

Examples of these osmotic laxatives include

• Lactulose syrup
• Macrogols (Movicol and Idrolax)
• Magnesium salts (Andrews liver salts, Epsom salts, Cream of magnesia)
• Phosphate enemas
• Sodium citrate (Microlette and Microlax enemas)

Different laxatives have different side effects. Bulk forming laxatives can cause wind and swelling in the abdomen. They can also block up your bowel. To prevent this you need to drink plenty of water.

Other types of laxatives can cause stomach cramps and wind, and large doses can cause diarrhoea. The side effects usually go away once your bowels have opened. But if you continue to have cramping or abdominal swelling, or if you develop diarrhoea, let your doctor know immediately.

Some herbal medicines claim to be laxatives that can help relieve constipation. Some are safe and do work. But we don’t know exactly how all of these medicines will react with your particular cancer drugs. Herbal products aren't necessarily all safe just because they are 'natural' and you can buy them over the counter at a health shop. So it is very important to let your doctor know if you are planning on taking any herbal medicine alongside your cancer treatment.

There is more information about herbal medicine in the complementary therapy section of CancerHelp UK. We are in the process of writing a more detailed section on the use of complementary therapies in cancer care. This will include more detailed information on the many types of herbal supplements, their uses and side effects.