Macrogol

What is macrogol?

Macrogol is a type of osmotic laxative used to relieve constipation. It works by drawing water into the bowel, which softens stools and makes them easier to pass. You can get it on prescription or you can buy it in a pharmacy. It is commonly available under brand names such as Movicol, Laxido, and CosmoCol which also contain electorlytes[1]. 

What is macrogol used for?

Macrogol is used in several situations to manage constipation-related problems[1]: 

• Occasional (short-term) constipation 

• Ongoing (chronic) constipation 

• Faecal impaction, which is severe constipation where stool becomes stuck in the rectum 

• Bowel cleansing before colonoscopy 

How does macrogol work?

Macrogol (most often macrogol 3350 or 4000) is not absorbed into the bloodstream. Instead, it remains in the bowel and works by[1]:

• Drawing water into the bowel and binding to it, increasing the water content of the stool 

• Softening the stool and stimulating a natural bowel movement 
  This usually leads to relief from constipation within 1-2 days. 

Who can take macrogol?

Macrogol is suitable for a wide range of people, but not everyone. It is usually safe for[1]: 

• Adults and children over 12 (paediatric versions are made for younger children aged 1month to 11 years) 

• Pregnant and breastfeeding women, but only under medical advice 

However, it should not be used by people with[1]: 

• A bowel or intestinal obstruction or perforation 

• Severe inflammatory bowel disease, such as Crohn’s disease or ulcerative colitis 

• An allergy to macrogol, PEG or any other ingredient in the product 

• A need to add thickeners to liquids to help you swallow them 

• Heart failure or an irregular heartbeat 

• A low-salt diet 

Please tell your doctor or pharmacist about any conditions you may have or medication you take before you start treatment, and always follow the instructions in the Patient Information Leaflet[2]. 

What is the typical dosage of macrogol?

The dose depends on what it’s being used for. Always follow the instructions from your doctor or pharmacist. Typical doses include[1]: 

• For constipation in adults (children will have a lower dose):  

• full-strength powder sachets (13g of macrogol) – 1sachet 1 to 3 times daily 

• half-strength powder sachets (6g of macrogol) – 1-2 sachets 1 to 3 times daily in divided doses 

• ready-to-drink solution – 1 sachet 1 to 3 times daily 

• liquid – 25ml diluted in 100ml of water 1 to 3 times daily 

• For faecal impaction in adults (children will have a lower dose):  

• full-strength powder sachets (13g of macrogol) – 4 sachets on day 1, increasing by 2 sachets a day, up to a maximum of 8 sachets a day, in divided doses 

• half-strength powder sachets (6g of macrogol) – 8 sachets on day 1, increasing by 4 sachets a day, up to a maximum of 16 sachets a day, in divided doses 

Only give macrogol paediatric sachets to children under 12 years old if a doctor has prescribed it.

How do you take macrogol?

Macrogol is taken as ready-to-drink sachets, as a diluted liquid and as a powder mixed with water. Here’s how to take the latter two forms[1]:

1. Empty the contents of a sachet or 25ml of the liquid into a glass. 

2. Add about 125ml of water for the full-strength sachet, 62.5ml for the half-strength sachet or 100ml for the liquid

3. Stir until the powder dissolves or liquid has mixed completely. 

4. Drink the mixture. After reconstitution the solution should be kept in a refrigerator. Macrogol usually starts working within 24 to 48 hours. 

Can you stop taking macrogol?

Yes, you can stop taking macrogol once your bowel movements become regular. However, stopping too soon can cause constipation to return. If you’re unsure, speak to your doctor or pharmacist for guidance[1]. 

What do you do if you take too much macrogol?

Taking too much macrogol can lead to unwanted side effects such as[1]: 

• Diarrhoea 

• Stomach cramps or discomfort 

• Electrolyte imbalance (in rare cases) 

If this happens, stop taking the medicine and drink plenty of fluids. Contact your doctor if symptoms continue or worsen. 

What do you do if you forget to take macrogol

If you forget to take a dose of macrogol just skip the missed dose and take the next dose at the usual time[1]. Do not take two doses at once to make up for a missed one.

What medicines can’t you take with macrogol?

Macrogol may affect how other medicines are absorbed. You should[1]: 

• Avoid taking any other oral medicines within 1 hour before or after taking macrogol 

Special care is needed with[1]: 

• Anti-epileptic drugs, which may be less effective 

• Thickened fluids used by people with swallowing difficulties 

There’s an increased risk of side effects when taking two different laxatives together, however, your doctor may recommend using both for a synergistic effect.  

Always inform your doctor or pharmacist about all medications and supplements you take before you start a new medicine, and follow the instructions in the Patient Information Leaflet[2]. 

What are the side effects of macrogol?

Most side effects are mild and temporary. Common side effects include[1]: 

• Bloating or wind 

• Stomach cramps 

• Nausea or vomiting 

• Indigestion 

• Diarrhoea, especially with high doses, and a sore bottom 

Rare but serious side effects may include[1]: 

• Electrolyte imbalances (such as low sodium or potassium) 

• Severe diarrhoea or vomiting 

• Extreme tiredness 

• Shortness of breath 

• Swollen ankles, feet, or legs (oedema) 

• Muscle weakness 

• Irregular heartbeat 

You should contact your GP if you experience any of these symptoms. In rare cases, the medicine may cause a serious allergic reaction (anaphylaxis). You should call 999 or visit A&E immediately if you believe this is happening[1]. 

Symptoms of anaphylaxis include[1]:  

• Difficulty breathing  

• Tightness in throat and chest  

• Swelling of the tongue or throat  

• Feeling faint or dizzy  

• Blue/grey skin or lips  

• Loss of consciousness 

If you experience any side effects, including those not listed, you are encouraged to report them via the Yellow Card Scheme or contact your doctor, pharmacist, or nurse. This information is intended as a summary for general awareness and does not replace professional medical advice. 

The information provided in the side effects section is not a comprehensive list of all possible side effects associated with this medication. For a complete list of side effects, please refer to the Patient Information Leaflet (PIL) provided with your medication or consult your healthcare professional[2]. 

Frequently asked questions about macrogol

How long does macrogol take to work? 
Usually within 24 to 48 hours[1]. 

Can I take macrogol every day? 
Yes, it can be taken daily under medical supervision, especially for chronic constipation[1]. 

Is macrogol safe during pregnancy? 
Yes, it is generally considered safe but always consult your doctor before use[1]. 

Can children take macrogol? 
Yes, but only certain formulations and doses are suitable for children. Always follow medical advice[1]. 

Can I mix macrogol with juice? 
It must be dissolved in water first, taking the resultant liquid is recommended, but you can mix it with juice to improve the taste if needed[1]. 

Does macrogol cause dependency? 
No, it does not cause physical dependency, even with long-term use[1]. 

What should I do if I vomit after taking macrogol? 
Wait and try again later. If vomiting continues, speak to your doctor[1]. 

Can I drive after taking macrogol? 
Yes, macrogol does not affect your ability to drive[1]. 

For the official NHS guide to macrogol, visit their website.