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Methylcellulose tablets (Celevac)

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The usual dose is 3-6 tablets taken twice a day. Break up the tablets in your mouth before you swallow.

If you are taking methylcellulose for constipation, drink plenty of water as you take the tablets.

If you are taking methylcellulose for diarrhoea, swallow the tablets with as little water as possible.

Type of medicineA bulk-forming laxative
Used forTo manage bowel function (constipation and diarrhoea)
Also calledCelevac®
Available asTablets

Methylcellulose is a laxative used to regulate bowel function - it can help manage constipation or diarrhoea.

Constipation is a common problem. It means either going to the toilet less often than usual to empty your bowels, or passing hard or painful stools. Constipation can be caused by a number of things. Not eating enough fibre or not drinking enough fluid can cause constipation. Some conditions (such as pregnancy) can cause constipation, as can a lack of exercise or movement (such as being ill in bed) and some medicines. When taken with a glassful of water, methylcellulose tablets absorb the water and swell to a soft gel consistency in your bowel. This increases the bulk of your stools and eases constipation by encouraging your bowels to move the stools through your digestive system.

Methylcellulose tablets can also be helpful to manage diarrhoea. When the tablets are swallowed with only a sip of water, they absorb water from the bowel. This helps prevent the loss of fluid from diarrhoea and changes the consistency of the stools making them more formed. This action helps to regulate the passage of food through the digestive systems in people with certain bowel disorders such as irritable bowel syndrome, diverticular disease, ulcerative colitis and after some types of bowel surgery.

Some medicines are not suitable for people with certain conditions, and sometimes a medicine may only be used if extra care is taken. For these reasons, before you start taking methylcellulose it is important that your doctor knows:

  • If you are pregnant or breast-feeding. Methylcellulose is not considered harmful to babies, but it is important that your doctor knows about this.
  • If you have any difficulty in swallowing.
  • If you are so constipated that you think you may have a blockage.
  • If you have been told you have a bowel infection.
  • If you are taking any other medicines. This includes any medicines you are taking which are available to buy without a prescription, such as herbal and complementary medicines.
  • If you have ever had an allergic reaction to a medicine.
  • Before you start the treatment, read the manufacturer's printed information leaflet from inside the pack. It will give you more information about methylcellulose and will provide you with a full list of the side-effects which you may experience.
  • Take methylcellulose tablets exactly as your doctor tells you to. It is usual to take a dose of 3-6 tablets, twice a day. Your doctor will tell you what dose is right for you. Break up the tablets in your mouth before you swallow them. You should not take a dose just before bedtime.
  • If you are taking methylcellulose for constipation, it is important for you to drink plenty of water at the same time as you take the methylcellulose tablets. Count out the correct number of tablets for your dose and swallow these with a large glassful (about 300 ml) of water.
  • If you are taking methylcellulose for diarrhoea, swallow the correct number of tablets for each dose with just a sip of water. Avoid drinking anything else during the half hour before you take the tablets and during the half hour after you have taken the tablets.
  • If you forget to take a dose, do not worry, just take the next dose when it is due. Do not take two doses together to make up for a forgotten dose.

The following information applies if you are taking methylcellulose tablets for constipation:

  • Sometimes it may take a few days before you feel the full benefit from a bulk-forming laxative such as methylcellulose. However, if after several days you do not feel that your symptoms are improving, or if they get any worse, you should speak with your doctor again.
  • Try to eat a balanced diet containing high-fibre foods such as wholemeal and wholegrain breads and cereals, fruit and vegetables, brown rice and wholemeal pasta. If you are not used to a high-fibre diet, it may be best to increase the amount of fibre you eat gradually.
  • Keeping your body active will help you to keep your digestive system moving, so try to take some regular daily exercise.
  • You may wish to include some foods that contain sorbitol in your diet. Sorbitol is a naturally occurring sugar. It is not digested very well and draws water into your bowel which has an effect of softening stools. Fruits (and their juices) that have a high sorbitol content include apples, apricots, gooseberries, grapes (and raisins), peaches, pears, plums, prunes, raspberries and strawberries.
  • Food such as pastries, puddings, sweets, cheese and cake can make constipation worse and are probably best avoided.
  • You can read more about how to prevent or treat constipation in the separate condition leaflets called Constipation in adults and Constipation in children.

Along with their useful effects, most medicines can cause unwanted side-effects although not everyone experiences them. The table below contains some of the ones which can occur with methylcellulose. You will find a full list in the manufacturer's information leaflet supplied with your medicine. Speak with your doctor or pharmacist if any of the following continue or become troublesome.

Methylcellulose side-effectsWhat can I do if I experience this?
Excess wind (flatulence), bloating, tummy (abdominal) discomfortThese effects should soon settle down as your body adjusts but, if they continue or become troublesome, speak with your doctor or pharmacist

If you experience any other symptoms which you think may be due to the tablets, speak with your doctor or pharmacist for further advice.

  • Keep all medicines out of the reach and sight of children.
  • Store in a cool, dry place, away from direct heat and light.

If you are due to have an operation or any dental treatment, tell the person carrying out the treatment which medicines you are taking.

If you buy any medicines, always check with a pharmacist that they are safe to take with your other medicines.

Never take more than the prescribed dose. If you suspect that you or someone else might have taken an overdose of this medicine, go to the accident and emergency department of your local hospital. Take the container with you, even if it is empty.

This medicine is for you. Never give it to other people even if their condition appears to be the same as yours.

Do not keep out-of-date or unwanted medicines. Take them to your local pharmacy which will dispose of them for you.

If you have any questions about this medicine ask your pharmacist.

Further reading & references

  • Manufacturer's PIL, Celevac® Tablets 500 mg; Amdipharm Mercury Company Limited, The electronic Medicines Compendium. Dated December 2013.
  • British National Formulary; 67th Edition (March 2014) British Medical Association and Royal Pharmaceutical Society of Great Britain, London

Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.

Original Author:
Helen Allen
Current Version:
Peer Reviewer:
Dr John Cox
Document ID:
3224 (v25)
Last Checked:
Next Review:
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