What are laxatives?

Laxatives are medicines that help prevent or treat constipation.

There are many types of laxatives. Each type of laxative works differently, but they all make it easier to pass bowel motions (poo).

Most laxatives do not need a doctor's prescription. You can buy laxatives over the counter from a pharmacy or from a supermarket.

Some types of laxatives may not be right for everyone. Talk to your doctor or pharmacist before taking them.

How do laxatives work?

Different types of laxatives work differently.

• Bulking agents work by adding fibre or 'bulk' to your stool. They also help move more water into your intestine, making it easier to push the stool out.
• Osmotic laxatives aren't easily absorbed by your body. When they reach your intestine, they pull more water into your bowel (colon). This softens and increases the size of your stool and can help you go to the toilet more easily and comfortably.
• Stimulant laxatives help your gut muscles contract, which makes them squeeze more and move stool through your body more quickly.
• Stool softeners and lubricants help make your stool easier to pass by drawing more water and fats into your stool.

What are laxatives used for?

Laxatives are medicines that help prevent or treat constipation. This is when you have trouble passing stools (faeces or poo).

Symptoms of constipation include:

• needing to strain to pass stools
• passing lumpy or hard stools
• feeling that your bowel isn't completely empty when you finish passing stools
• having fewer than 3 bowel movements per week

Many people have constipation occasionally. It is more common in children, people who take strong pain medicines (such as opioids) and during pregnancy.

What forms of laxatives are available?

The forms of laxatives include:

• oral liquids
• dissolvable powders
• tablets or capsules
• suppositories
• enemas

What are the side effects of laxatives?

Side effects will vary depending on the type of laxative you are using.

Bulking agents — work like high fibre foods in your diet. This means that they have few side effects and are usually safe to take long-term. However, some people might feel bloated or have flatulence (passing wind). It's important to drink lots of water when taking bulking agents for constipation.

Osmotic laxatives — are usually mild when you take them by mouth, but they can cause bloating and increased wind.

Stimulant laxatives — can cause abdominal cramping. They should not be used in large quantities or for a long time because this might cause dehydration. Using stimulant laxatives long term is not recommended and can make constipation worse.

Since many laxatives work by attracting more water into your stool, it's important to make sure you drink enough water.

Some stool softeners and lubricants can reduce absorption of certain vitamins absorbed in your gut. Ask for your doctor or pharmacist for advice before using them long term.

How do I take laxatives?

How you take laxatives will depend on the form they come in.

The table below has information about taking different types of laxatives.

How do I take laxatives used for bowel preparation ('bowel prep')?

Laxatives are often used to help clean out your intestines before procedures such as colonoscopy. This is called bowel preparation or 'bowel prep'.

There are different types of laxatives, which can be taken by mouth or used in the rectum, when preparing your bowel. Your doctor will choose the right type for you. They will also tell you what you can eat or drink during this time. It's important to read and follow the instructions on the packet.

You will usually take bowel prep in the afternoon or evening before your procedure.

Taking bowel prep will make you have diarrhoea, so make sure you can get to a toilet. Other common side effects include nausea, bloating or swelling in your belly.

In some people, bowel prep can cause dehydration. If you feel dizzy or unwell while taking bowel prep, contact your doctor.

For more information about bowel prep, visit Bowel Cancer Australia.

When should I see my doctor?

If you are constipated and are considering taking laxatives, it's a good idea to see your doctor. They can suggest the best treatment strategy, like which medicine to take and for how long.

You should also see your doctor if the treatment they prescribe for your constipation hasn't helped. Laxatives usually work within 24 hours.

If you experience diarrhoea after using laxatives, stop the medicine. If your symptoms continue, see your doctor.

Some types of laxatives can make you more likely to get dehydrated. If you have symptoms of dehydration, stop the medicine and see your doctor.

When to seek urgent care

See your doctor urgently if you have any of these symptoms:

• abdominal (tummy) pain, cramping, nausea and vomiting — these could be signs of bowel obstruction (blockage)
• stools that are slimy, pale, very dark or have blood
• bleeding from your rectum (bottom)

Are there any alternatives to laxatives?

There are many things you can do to help relieve and prevent constipation:

• Eat more high fibre foods.
• Drink plenty of water and other fluids.
• Get regular physical activity.
• Go to the toilet when you need to, without delaying.

Learn more about constipation and ways to treat it.

Resources and support

Continence Health Australia has information and advice about managing constipation.

The Gastroenterological Society of Australia (GESA) has information on constipation and bowel preparation.

Dietitians Australia can help find a dietitian nearby if you need help changing your diet because of constipation.

If you prefer to read in languages other than English, the Royal Children's Hospital Melbourne has factsheets on constipation and laxatives.

You can also call the healthdirect helpline on 1800 022 222 (known as NURSE-ON-CALL in Victoria). A registered nurse is available to speak with you 24 hours a day, 7 days a week.