Laxatives

Laxatives can help you empty your bowels if you're constipated. Before taking laxatives you need to be sure that you really are constipated. Normal bowel movements vary from person to person.

If you have cancer, you should always check with your doctor or nurse before taking any type of laxative. They will want to find out what's causing your constipation before recommending treatment for you.

You might not be able to take some types of laxatives if you have a bag on your tummy (abdomen) such as a colostomy or ileostomy to collect your poo.

How you have laxatives

You can buy many laxatives over the counter without a prescription. Other types of laxatives need a prescription.

Before buying over the counter laxatives speak to the pharmacist to explain:

• your symptoms
• any health problems you may have
• any medicines you are taking

This will help them decide on the best treatment to help you.

It's important to read and follow the information the laxatives come with. Depending on the laxative you have there may be specific instructions. For example, it's important to drink plenty of fluids if you're taking bulk forming or osmotic laxatives, as they can cause dehydration. 

Laxatives come as:

• tablets, capsules or granules that you swallow

• powders that can be made into a drink by adding water or fruit juice

• liquids or gels that you have into the back passage (enemas)

• a capsule (suppository) that you insert into your back passage

Types of laxatives

There are several types of laxatives. Each work in a different way and they are grouped together in the way they work. Not every laxative is suitable for everyone.

Your doctor or nurse will want to find out more about your symptoms and the cause of your constipation before they choose the right treatment for you.

Bulk forming laxatives

Bulk forming laxatives contain high amounts of fibre . These work by holding onto water and increasing the size of your poo inside your bowel. It also helps to soften the poo. This encourages your bowels to move and push the poo out. This type of laxative can take a few days to work properly. Examples include:

• Fybogel

• sterculia

• methylcellulose, this also acts as a stool softener

Stool softener

These work by softening the poo. They do this by drawing more water and fat into the poo. Examples include:

• docusate sodium, this also acts as a stimulant laxative

• arachis oil enema

Side effects of docusate sodium can include tummy cramps.

Stimulant laxatives

Stimulant laxatives work by encouraging the muscles in your bowel to contract. This helps pass the poo along your bowel to your back passage. It can take between 6 and 12 hours to work. Examples include:

• bisacodyl

• senna also known as Senakot

• sodium picosulfate

• co-danthrusate

• glycerol suppositories

Osmotic laxatives

These work by drawing more water into your bowel. This makes your poo softer and easier to pass. Examples include:

• lactulose

• macrogols such as Movicol

• magnesium salts such as original Andrews salts, Epsom salts, milk of magnesia

Opioid receptor blockers

People having opioid type painkillers often have constipation. Drugs such as methylnatrexone (Relistor) and naloxegol (Moventig) can help. It reduces constipation in people having opioid painkillers when other laxatives have not worked.

Side effects of laxatives

Different laxatives have different side effects. 

Bulk forming laxatives can cause wind and a swollen 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. Having large doses of laxatives can cause diarrhoea.

The side effects usually go away once your bowels have opened. But let your doctor or nurse know straight away if you continue to have cramping or abdominal swelling, or if you get diarrhoea.

Taking herbal supplements for constipation

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 some of these medicines will react with your cancer treatment. 

Herbal products aren't necessarily all safe. Although they are natural products and you can buy them over the counter at a health shop, some might be harmful to take alongside cancer treatment. So it is very important to let your doctor know if you are planning to take any herbal medicine alongside your cancer treatment.