Macrogol: How to Actually Use Laxido and Movicol
Why the water is the medicine, what the real dose range is, and the much higher regimen used only for impaction.
Part of the Complete Constipation Guide.
Key fact: Each sachet is dissolved in 125ml of water — and the water is part of the medicine, not a way of swallowing it. The usual adult dose for constipation is 1 to 3 sachets a day, adjusted to response, not a fixed single sachet.
What macrogol is
Macrogol — sold as Laxido, Movicol and several generic versions — is an osmotic laxative supplied as a powder in sachets. The powder is a large inert molecule that is not absorbed and not fermented by gut bacteria, which is why it causes less wind and bloating than lactulose.
Because it is not absorbed and not broken down, it does essentially one thing: it holds water in the bowel all the way through.
Why the water matters
This is the part that determines whether it works. The macrogol molecule binds the water it is dissolved in and carries it through the bowel rather than letting it be absorbed on the way. The stool is softened by that water.
So the 125ml per sachet is a dose, not a serving suggestion. Taking the powder in a small splash of water, or sprinkling it on food, delivers the macrogol without the water it is supposed to be carrying — which is the single commonest reason people report that it did nothing.
The dose for ordinary constipation
| Adults, adolescents and older people | |
|---|---|
| Usual dose | 1 to 3 sachets daily in divided doses, according to response |
| Longer-term use | The dose may be reduced to 1 to 2 sachets daily |
| Water per sachet | 125ml |
| Usual course length | Normally no more than 2 weeks, though courses can be repeated if needed |
"According to response" is the operative phrase. Start at one sachet, and if the stool is still hard after a couple of days, go to two, then three. Titrating is expected and is how the product is designed to be used — taking one sachet a day indefinitely and concluding it does not work is the wrong test.
Longer courses are common in chronic constipation and are managed with a prescriber rather than indefinitely over the counter.
Mixing it, and making it drinkable
- Dissolve fully before drinking. Undissolved powder is gritty and unpleasant and puts people off
- Chill it. Made up and refrigerated, it is considerably more palatable. Check the leaflet for how long a made-up solution can be kept — typically it can be prepared in advance and refrigerated for a limited period
- Drink it reasonably promptly rather than sipping it over hours
- Divide the dose if taking two or three sachets — morning and evening is easier than three at once
- Different flavours exist, including plain and lime, and they are not equally tolerable to everyone. Switching brand or flavour is a reasonable fix for someone who cannot face it
How long it takes to work
Usually one to three days, sometimes sooner. It does not produce an urgent result the way a stimulant can, and that is intentional — it is softening what is there rather than pushing it.
If after three days at an adequate dose the stool is soft but still not coming, the problem is transit rather than consistency, and a stimulant is the logical addition — see laxatives compared.
The much higher dose used for impaction
For faecal impaction the licensed adult dose is 8 sachets daily, all taken within a 6-hour period, for no more than 3 days. The eight sachets can be dissolved together in one litre of water. This is a clinician-directed regimen, not something to start on your own — it needs impaction to be confirmed, obstruction excluded, and a plan for what follows.
One important modification: anyone with impaired cardiovascular function should space the intake so that no more than two sachets are taken in any one hour, because of the fluid and salt load.
After disimpaction, treatment normally continues at a maintenance dose to stop it recurring. Faecal impaction and overflow soiling covers how impaction presents and why the treatment differs.
The five common mistakes
| Mistake | Why it matters |
|---|---|
| Not enough water | The water is the active part of the treatment. 125ml per sachet. |
| Not titrating the dose | One sachet is the starting point, not the dose. Up to three daily is standard. |
| Giving up on day two | One to three days is the expected onset. |
| Stopping the moment things improve | Reduce gradually rather than stopping outright, or the pattern returns and the laxative gets the blame. |
| Using it for the wrong problem | If stool is already soft and the issue is that nothing moves, more softening will not help. |
Who should not take it
- Known or suspected bowel obstruction or perforation
- Ileus — a bowel that has stopped moving
- Severe inflammatory bowel conditions, including active Crohn's disease, ulcerative colitis and toxic megacolon
- Known hypersensitivity to the ingredients
- Children under 12 — the standard adult product is not recommended; paediatric preparations exist and are dosed differently
Impaired cardiovascular function and impaired kidney function do not rule it out but change how it is used, so both are worth mentioning to whoever supplies it.
Stopping it
Reduce the number of sachets gradually once bowel movements have been comfortable and regular, rather than stopping from three a day to none. The aim you are reducing towards is a soft, formed stool passed without straining — if reducing the dose loses that, you have reduced too far or too fast.
Keeping the fibre, fluid, activity and toilet routine going is what allows the dose to come down at all. Those are covered on the main constipation page.
Each sachet is dissolved in 125ml of water. The water is part of how the medicine works, because the macrogol holds that water and carries it through the bowel to soften the stool. Taking the powder with only a small amount of liquid is the commonest reason it appears not to work. For ordinary constipation in adults the usual dose is 1 to 3 sachets daily in divided doses, adjusted according to response, reducing to 1 to 2 sachets daily for longer-term use. The much higher regimen of 8 sachets a day is only for confirmed faecal impaction and is clinician-directed. Usually one to three days, sometimes sooner. It softens stool rather than stimulating the bowel, so it does not produce the rapid effect of a stimulant laxative. If after three days at an adequate dose the stool is soft but still not passing, the problem is transit rather than consistency. A standard course does not normally exceed two weeks, although courses can be repeated. Longer-term use is common in chronic constipation and is managed with a prescriber, often at a reduced dose of one to two sachets daily. It is contraindicated in known or suspected bowel obstruction or perforation, ileus, and severe inflammatory bowel conditions including toxic megacolon, and in anyone hypersensitive to the ingredients. The standard adult product is not recommended for children under 12.Frequently Asked Questions
How much water do you mix Movicol or Laxido with?
How many sachets of macrogol can you take a day?
How long does macrogol take to work?
Can you take macrogol long term?
Who should not take Laxido or Movicol?
References
- NHS. Constipation. nhs.uk
- National Institute for Health and Care Excellence. Clinical Knowledge Summary: Constipation. cks.nice.org.uk
- Electronic Medicines Compendium. Movicol 13.7g powder for oral solution: Summary of Product Characteristics. medicines.org.uk
- National Institute for Health and Care Excellence. Suspected cancer: recognition and referral (NG12). nice.org.uk
- National Institute for Health and Care Excellence. Quantitative faecal immunochemical testing to guide referral for colorectal cancer in primary care (DG56). nice.org.uk
Medical disclaimer: This article is for informational purposes only and does not constitute medical advice. A persistent change in bowel habit, rectal bleeding or unexplained weight loss should always be assessed rather than treated as constipation. Always consult a qualified healthcare professional for diagnosis and treatment. In a medical emergency, call 999.