Overview
Different types treat different kinds of constipation. Polyethylene glycol (PEG) is first-line and safe for daily use. Stimulant laxatives are for short-term only.
What it is used for
Functional constipation
IBS-C
Opioid-induced constipation
Bowel preparation for colonoscopy (high-dose PEG)
Hard stools that cause hemorrhoids or fissures
Common side effects
Bulk laxatives: bloating, gas (often improves over weeks)
Osmotic laxatives: bloating, sometimes loose stools if too much
Stimulant laxatives: cramping, occasional electrolyte issues with long-term use
Prokinetics: headache (common in first week), nausea, diarrhea
When to See a Doctor
Do not stop a prescribed medicine on your own. Speak to your doctor or pharmacist about side effects, interactions or any doubt, and seek urgent care for the serious warning signs above.
Drug class and examples
Laxatives — multiple subclasses
Bulk: psyllium (Metamucil, Fybogel), methylcellulose. Osmotic: PEG (Movicol, Forlax, Miralax), lactulose, magnesium hydroxide. Stimulant: senna (Senokot), bisacodyl (Dulcolax). Prokinetic: prucalopride (Resolor), linaclotide (Linzess), lubiprostone.
How it works
Different mechanisms: **Bulk laxatives** absorb water and add bulk to stool. **Osmotic laxatives** pull water into the bowel. **Stimulant laxatives** trigger intestinal contractions. **Prokinetics** speed up colonic transit by acting on serotonin receptors.
How to take it
**Psyllium** — start at 1 teaspoon daily, mix in 240 mL water, drink IMMEDIATELY before it thickens. Gradually increase to 1 tablespoon (5-10 g). Drink lots of water.
**PEG** — 17 g (one sachet) mixed in 250 mL water once daily. Adjust to 1-2 sachets/day for 1-3 soft stools. Safe long-term.
**Senna or bisacodyl** — for short-term use only (a few days). Take at bedtime; works overnight.
**Prucalopride** — 2 mg daily (1 mg in elderly). Taken in the morning.
Serious side effects — act on these
• Severe abdominal pain or vomiting — Possible obstruction or other serious cause — stop laxative and see doctor.
• No bowel movement after several days of treatment — Possible obstruction — investigate.
• Heart palpitations or muscle weakness with chronic stimulant use — Possible electrolyte imbalance — needs blood test.
Interactions
Bulk laxatives reduce absorption of other medications — separate by 2 hours. Magnesium-containing laxatives can interact with kidney drugs. Most other laxatives have few significant interactions.
Monitoring
No monitoring for short-term use. Long-term high-dose stimulant laxative use: check potassium and magnesium yearly. Long-term lactulose: check electrolytes if also on diuretics.
When to stop or review
Step-down approach: once regular soft stools achieved, reduce dose gradually. Stimulant laxatives: stop within 1-2 weeks unless under medical supervision. PEG: safe to continue indefinitely.
Pregnancy and breastfeeding
PEG and bulk laxatives are first-line in pregnancy and generally safe. Avoid stimulant laxatives in pregnancy unless necessary. Consult your obstetrician.
Questions to ask your doctor
• Which laxative is best for me?
• Is PEG safe long-term?
• Can I become "dependent" on stimulant laxatives?
Source and review
This guide comes from the Saudi Gastroenterology Association (SGA) patient library, prepared by the SGA Patient Education Panel. Last reviewed: 2026-04-24. It is for education and does not replace your doctor's advice.
Frequently Asked Questions
What is Laxatives (Bulk, Osmotic, Stimulant, Prokinetic) used for?
How does Laxatives (Bulk, Osmotic, Stimulant, Prokinetic) work?
What are the side effects of Laxatives (Bulk, Osmotic, Stimulant, Prokinetic)?
When should I call my doctor about Laxatives (Bulk, Osmotic, Stimulant, Prokinetic)?
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