There are several types of laxative – some of which you can buy without a prescription. The main types are:
- bulk-forming laxatives (also known as fibre supplements), such as wheat or oat bran, ispaghula husk, methylcellulose and sterculia
- osmotic laxatives, such as lactulose, macrogols, sodium citrate enema and phosphate enema
- stimulant laxatives, such as senna, and glycerol or bisacodyl suppositories
- faecal softener laxatives, such as arachis oil
Each type of laxative works in a different way to help relieve or prevent constipation.
- Bulk-forming laxatives work by increasing the amount of fibre you have in your diet so you produce more faeces. This then encourages your bowels to move and push the faeces out.
- Osmotic laxatives work by increasing the amount of water that stays in your faeces, which makes them easier to pass.
- Stimulant laxatives work by stimulating nerves in your bowel so that your intestine moves and pushes the faeces out.
- Faecal softener laxatives work by lubricating and softening your faeces, which makes them easier to pass.
Laxatives are available as:
- tablets, syrups or capsules you swallow
- powders or granules that you mix in water
- suppositories (capsules you put inside your back passage)
Sometimes, a laxative is given as an enema (liquid injected through a thin tube into your back passage). Enemas and suppositories work within minutes to clear your bowel.
Choosing the right type of laxative
Bulk-forming laxatives are usually recommended as the first type to try, especially if you find it difficult to get more natural fibre in your diet. Your doctor may also prescribe a bulk-forming laxative if you have a colostomy or ileostomy bag, irritable bowel syndrome, piles (haemorrhoids) or an anal fissure.
Bulk-forming laxatives usually come as powders or granules that you mix in water. It's important to drink enough fluids so that the extra bulk doesn’t build up in your bowel and cause a blockage. Bulk-forming laxatives may take two to three days to start working.
If a bulk-forming laxative doesn’t work or isn’t tolerated you may need an osmotic laxative. This too may take two to three days to start working. You must drink enough fluids while taking osmotic laxatives to avoid getting dehydrated.
Stimulant laxatives should only be used if other types of laxatives haven’t worked. They come as tablets, liquids, suppositories and enemas. Tablets and liquids work within six to 12 hours, so you should take them at night for an effect the next morning.
Faecal softener laxatives
Faecal softeners come as medicines taken by mouth, as well as suppositories or enemas. The enemas usually work faster.
Laxatives are usually only recommended for short-term use if changes to your diet, such as increasing your fibre and fluid intake, haven't worked. Taking laxatives over a long time can be harmful. It’s generally recommended that you stop taking laxatives once your bowel movements have returned to normal.
Sometimes you may need to take laxatives for weeks or months, especially if you have chronic constipation. However, you shouldn’t take laxatives for longer than a week unless your doctor advises you to. Also, you shouldn't give laxatives to children unless your doctor has prescribed them.
Always read the patient information leaflet that comes with your medicine, and if you have any questions, ask your pharmacist or doctor for advice.
Check with your GP or pharmacist before taking a laxative if:
- you’re pregnant or breastfeeding
- you know that your kidneys or liver aren't working properly
- you have an inflammatory bowel disease such as ulcerative colitis
This section doesn't include every possible side-effect of laxatives. Please read the patient information leaflet that comes with your medicine for more information. However, some common side-effects are listed below.
- Bulk-forming laxatives can cause bloating, wind, stomach pains and cramps. Rarely, they can block your bowel.
- Osmotic laxatives can cause bloating, wind, nausea and stomach cramps. You may also become dehydrated and get a headache.
- Stimulant laxatives can cause stomach pains and cramping, and diarrhoea.
- Suppositories and enemas can cause abdominal pain and irritate the skin around your anus.
Check with your GP or pharmacist before you take any other medicines or herbal remedies at the same time as a laxative.
The main types of laxatives are shown in the table below.
All medicines have a generic name. Many medicines also have one or more brand names. Generic names are usually written in lower case, whereas brand names start with a capital letter.
There are many different products marketed for constipation. Some have more than one ingredient, or different ingredients sold under the same brand name. Ask your pharmacist for advice.
Generic names Examples of common brand names Bulk-forming laxatives bran ispaghula husk Fibrelief, Fybogel, Isogel, Ispagel Orange, Regulan methylcellulose Celevac sterculia Normacol, Normacol Plus Osmotic laxatives lactulose Duphalac, Lactugal, Laevolac macrogols Movicol, Movical-Half, Movicol-Paediatric magnesium salts Phillips Milk of Magnesia, Epsom Salts, Original Andrews Salts phosphates Fleet enema, Fletchers' Phosphate Enema sodium citrate Microlette, Micralax, Relaxit Stimulant laxatives bisacodyl Dulcolax co-danthramer Codalax co-danthrusate (with docusate sodium) Normax docusate sodium Dioctyl, Docusol, Norgalax Micro-enema (enema) glycerol Glycerin suppositories senna Manevac, Senokot sodium picosulfate Dulcolax Pico Liquid, Dulcolax Pico Perles Faecal softener laxatives arachis oil Arachis oil enema liquid paraffin Liquid paraffin oral emulsion
Can I take laxatives to lose weight?
No, you shouldn't do this. It doesn't work and it can be dangerous. Taking laxatives occasionally won't be harmful but they shouldn't be taken regularly. The best way to lose weight is by eating a healthy diet and exercising regularly.
Laxatives can't help you lose weight. They don't stop you absorbing the food you have eaten. Laxatives work on the large bowel and most of the calories in your food are absorbed before the food reaches your large bowel. If you do notice that you have lost weight, it will be short-term and caused by a loss of water or faecal mass rather than fat.
When you take laxatives, they help you have a bowel movement. But, at the same time, you lose water, minerals, electrolytes and indigestible fibre that help maintain a healthy body. This is safe when laxatives are only taken occasionally, but frequent long-term laxative use can cause serious health problems.
Laxatives can cause dehydration, which can make you feel weak, faint and cause blurry vision. Disrupting the electrolyte and mineral balance in your body by taking laxatives regularly can cause muscle aches and pains, and make your heart race (palpitations).
The best way to lose weight is by eating a healthy diet and exercising.
I’m constipated. How long should I wait before I try taking laxatives?
If you’ve tried increasing your fibre and fluid intake, but are still finding it difficult or painful to have a bowel movement, consider taking laxatives.
How often you have a bowel movement is specific to you. Most people have a bowel movement at least three times a week. If you haven't had a bowel movement as frequently as is normal for you, or you’re having to strain, then you may be constipated.
Increasing your dietary fibre and fluid intake, as well as exercising regularly, can help ease constipation. If you find it difficult to add natural fibre to your diet, your doctor or pharmacist may advise you to try a bulk-forming laxative.
Ask your pharmacist or GP for advice.
Is it OK to increase the amount of fibre in my diet at the same time as taking laxatives?
If you don't think you're getting enough fibre, you should try to gradually increase the amount in your diet before you start taking laxatives.
Before trying a laxative, you should increase the amount of fibre in your diet. For example, you can add bran to your food or eat a diet that’s rich in fibre. Sources of fibre include fruit, vegetables, beans and pulses. Increase dietary fibre gradually as it can cause bloating and wind.
You should also make sure you’re drinking enough water and exercising regularly. You should aim to do at least 150 minutes (two and a half hours) of moderate physical activity during the week.
There are different types of laxative available if lifestyle changes don't help. Certain types of laxative may be more effective than others for you, depending on what’s causing your constipation. Ask your pharmacist or GP for advice and explain your symptoms to them.
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