Movicol is a sachet of powder dissolved in water, used to treat constipation and to clear faecal impaction. It works by holding water in the stool rather than by stimulating the bowel, which makes it gentle enough for long-term use, in pregnancy, and in children.
What is Movicol?
Movicol does not appear on the South African Medicine Price Registry under that name, so this page does not assert its registered composition — check your own pack.
Movicol is internationally an osmotic laxative built on macrogol 3350 — also called polyethylene glycol 3350, or PEG 3350 — combined with a small amount of sodium chloride, sodium bicarbonate and potassium chloride. Those salts are there to stop the macrogol drawing salts out of the body along with the water.
How it works is what makes it different from most laxatives.
Macrogol is a large, inert molecule that is not absorbed and is not broken down by gut bacteria. It passes the whole length of the bowel unchanged, and because each molecule binds water strongly, it holds water in the stool all the way through. The result is a softer, bulkier stool that is easier to pass, and gentle stretching of the bowel wall that prompts a normal urge.
It does not stimulate or irritate the bowel. Stimulant laxatives such as senna and bisacodyl work by provoking contraction, which produces cramping, and which the bowel can become reliant on. Macrogol produces neither, which is why it is suitable for months or years of use where needed, and why it is the preferred laxative for children.
It is dose-flexible in a way most laxatives are not. One sachet daily is typical for ordinary constipation; a much larger number over a short period is used to clear an impaction, under medical direction.
Dissolve it fully and drink the whole glass. The water is not optional — it is the medicine. Taking the powder with too little water can make constipation worse.
Generic macrogol sachets contain the same thing and are considerably cheaper.
What is Movicol commonly used for?
- Chronic constipation in adults, where it is a first-line choice for ongoing treatment.
- Constipation in children, where macrogol is the recommended first option in most guidelines — palatable, effective, and safe long term.
- Faecal impaction, where a high-dose regimen over one to three days clears a hard mass without an enema. This should be done on medical advice.
- Constipation in pregnancy and after childbirth, where it is among the safest options.
- Opioid-induced constipation, near-universal on codeine, tramadol or morphine and not improving with time. Anyone starting a regular opioid should be started on a laxative at the same time.
- Constipation from other medicines — iron, some antidepressants, calcium channel blockers.
- Maintaining softer stools after anal surgery, with haemorrhoids or a fissure, where straining must be avoided.
- Bowel preparation before a colonoscopy, in higher-volume formulations.
It takes one to three days to work. This is the most common misunderstanding — people take it, nothing happens by that evening, and they conclude it has failed. It is not a stimulant and does not act overnight.
The other measures genuinely matter: more fibre, considerably more fluid, regular activity, and going when you feel the urge rather than delaying. Macrogol works better alongside these, not instead of them.
Children need a different approach from adults. Childhood constipation is often driven by a cycle of a painful hard stool, then withholding, then a harder stool. Treatment usually needs to continue for months after things seem normal, to break that cycle — stopping as soon as the child is regular is the commonest reason it comes straight back.
How Movicol fits into this medicine category
| Group | Examples | How it works |
|---|---|---|
| Osmotic laxatives | Macrogol (Movicol), lactulose | Hold water in the stool; gentle, no cramping |
| Bulk-forming | Ispaghula, psyllium | Add bulk; need plenty of fluid |
| Stimulants | Senna, bisacodyl | Provoke contraction; cramping; short-term |
| Stool softeners | Docusate | Soften; weak on their own |
| Suppositories and enemas | Glycerin, phosphate | Rapid, local, for impaction |
| Antispasmodics | Hyoscine (Hyospasmol) | Cramping, not constipation |
| Anti-nausea | Metoclopramide (Adco-Contromet) | Nausea and stomach emptying |
Macrogol is generally preferred over lactulose — it works at least as well with less bloating and wind, and it is not fermented by gut bacteria.
See the digestive and stomach medicines hub.
What to check before using Movicol
Do not use it if you might have a bowel obstruction. This is the important contraindication. Speak to a doctor rather than self-treating if you have:
- Severe abdominal pain, a hard swollen abdomen, or vomiting — particularly if you have not passed wind.
- A known or suspected bowel obstruction or perforation.
- Severe inflammatory bowel disease or toxic megacolon.
Also tell your doctor or pharmacist if you:
- Have heart failure, kidney disease, or are on a low-sodium diet. The sachets contain salts.
- Have swallowing difficulties, where the volume of fluid may be a problem.
- Take other medicines, particularly at high macrogol doses — absorption of some medicines can be reduced while the bowel is being flushed.
- Are pregnant or breastfeeding. Macrogol is generally considered among the safest laxatives, but confirm.
- Are giving it to a child. Paediatric formulations and doses exist — use those, not an adult sachet.
- Have new constipation over the age of 45 to 50, which warrants assessment rather than indefinite laxative use.
Practical points:
- Dissolve each sachet fully in the stated volume of water and drink it all.
- Give it one to three days.
- Adjust the dose to produce a soft stool, not diarrhoea.
- Drink plenty of fluid generally, throughout the day.
- For children, continue for the duration advised, usually well beyond the point at which things seem normal.
- Do not stop abruptly after long use — reduce gradually, or constipation often returns immediately.
Possible cautions and when to ask a pharmacist or doctor
Common effects are mild: bloating, wind, mild abdominal discomfort, nausea and loose stools. Loose stools usually mean the dose is slightly too high.
Get emergency help for:
- Severe abdominal pain with a hard, swollen abdomen, particularly with vomiting and no passage of wind — possible obstruction.
- Vomiting blood, or black tarry stools.
- Swelling of the face, lips or tongue, or difficulty breathing.
- Severe watery diarrhoea with dizziness, confusion or reduced urine output — dehydration, especially in a child or older person.
Seek prompt advice for:
- Rectal bleeding, or blood mixed into the stool.
- Persistent vomiting, or inability to keep fluids down.
- Marked weakness, muscle cramps, palpitations or unusual tiredness — possible salt disturbance at high doses.
- A rash or itching.
- No bowel movement after several days on treatment.
See a doctor rather than continuing to self-treat if:
- Constipation is new and persistent, particularly over the age of 45 to 50.
- There is unintentional weight loss, rectal bleeding, or anaemia.
- There is a persistent change in bowel habit — narrower stools, alternating constipation and diarrhoea.
- There is family history of bowel cancer.
- Constipation alternates with diarrhoea, or comes with severe pain.
- You need a laxative most days, indefinitely, without a known reason.
- A child has constipation with soiling, pain on passing stool, or blood — this needs proper management, and it is very treatable.
That first group matters. Constipation is usually benign, but a persistent change in bowel habit in an adult over 45 is one of the ways bowel cancer presents, and treating the symptom is how the diagnosis gets delayed.
Related medicine guides
Frequently asked questions
What is Movicol used for? Treating constipation and clearing faecal impaction. It is an osmotic laxative based on macrogol, which holds water in the stool.
How long does it take to work? One to three days. It is not a stimulant and does not act overnight — this is the commonest misunderstanding about it.
Is it safe for long-term use? Yes. It does not stimulate or irritate the bowel and does not cause dependence, which is why it is used for months or years where needed.
Can children take it? Yes — macrogol is the recommended first choice for constipation in children. Use the paediatric formulation and dose, and continue for as long as advised.
Is it safe in pregnancy? It is among the safest laxative options, but confirm with your doctor or pharmacist.
Do I have to drink the whole glass? Yes. The water is the medicine — macrogol works by holding that water in the stool. Too little water can make constipation worse.
How is it different from senna or bisacodyl? Those stimulate the bowel to contract, causing cramping, and are for short-term use. Macrogol softens without stimulating.
Can I stop once I am regular? Reduce gradually rather than stopping dead, particularly after long use or in a child, or constipation often returns immediately.