Polyethylene glycol
- Class: Osmotic laxative
- Used for: constipation
- Say it: pol-ee-ETH-ih-leen GLYE-kol
- Forms: powder
POLYETHYLENE GLYCOL is a long POLYMER chain that grabs many water molecules and drags them along to the rectum.
Nothing is absorbed and no nerve is stimulated — it is pure osmotic physics. That is why it suits months of use where a stimulant laxative does not.
Polyethylene glycol is an inert polymer that binds water by hydrogen bonding and carries it to the rectum. Nothing is absorbed, no nerve is stimulated and no electrolyte is lost — which is why it suits long-term use.
Side effects
Common: bloating, nausea, stomach cramps
Serious:
Typical dose
17 g (one sachet) dissolved in water, once daily
Grams, not milligrams. Disimpaction uses much higher doses over a few days.
Check yourself
Why is macrogol suitable for long-term use when a stimulant laxative is not?
- It is inert and unabsorbed, acting only by holding water in the stool
- It is more potent so less is needed
- It is absorbed and acts systemically
- It stimulates the bowel more gently
Show answer
A. It is inert and unabsorbed, acting only by holding water in the stool
Macrogol does not stimulate the enteric nerves at all — it is pure osmotic physics. With nothing absorbed and no electrolyte shift, it can be continued for the months that chronic constipation genuinely requires.
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