Constipation Remedies That Work Fast, Ranked by Evidence
When you’re constipated, two questions matter: how fast will this work, and does it actually work? Here is the answer for the most common options, using the 2023 gastroenterology guideline from the US and the 2025 dietetics guideline from the UK.
How fast each option works
Timings are typical ranges from product labels and drug references. Individual responses vary.
| Option | Typical time to work | Best for |
|---|---|---|
| Bisacodyl suppository | 15 minutes to 1 hour | Fast rescue |
| Magnesium citrate solution or milk of magnesia | 30 minutes to 6 hours | Occasional, fast relief |
| Stimulant tablets (bisacodyl, senna) | 6 to 12 hours, usually overnight | Short-term relief |
| Polyethylene glycol (PEG, e.g. MiraLAX) | 1 to 3 days | Steady relief, including longer use |
| Psyllium fiber | About 1 to 3 days | Long-term regularity |
| Kiwifruit, rye bread, mineral water | Days to weeks | Everyday, food-first approach |
How strong the evidence is
The 2023 guideline from the American Gastroenterological Association and the American College of Gastroenterology (AGA–ACG) rated each over-the-counter option for chronic constipation:
| Option | Recommendation | Certainty of evidence |
|---|---|---|
| Polyethylene glycol (PEG) | Strong | Moderate |
| Bisacodyl or sodium picosulfate (short-term or rescue) | Strong | Moderate |
| Fiber supplements (psyllium) | Conditional | Low |
| Senna | Conditional | Low |
| Magnesium oxide | Conditional | Very low |
| Lactulose (if OTC options fail) | Conditional | Very low |
The guideline also covers prescription drugs (linaclotide, plecanatide, prucalopride, lubiprostone) for people who don’t respond to over-the-counter options.
The 2025 British Dietetic Association (BDA) guideline, led by King’s College London, looked at foods, drinks and supplements. It supported:
- kiwifruit, 2–3 a day, with fewer side effects than prunes or psyllium in its review;
- rye bread and prunes;
- high-mineral-content water;
- psyllium and magnesium oxide; probiotics in general, without naming a specific strain.
It found that generic “high-fiber diets” and senna supplements lacked strong evidence, and suggested trying a food for at least 4 weeks.
A sensible order to try things
This is general information to discuss with your doctor or pharmacist, not a personal treatment plan.
- Everyday base: kiwifruit or prunes, enough fluids, and if you supplement, psyllium built up slowly. See psyllium: dose and real cost.
- If that isn’t enough: PEG has the strongest recommendation for chronic constipation. Magnesium oxide is an option for people with healthy kidneys: see magnesium for constipation.
- For a fast rescue: a bisacodyl suppository or a stimulant tablet at night, for short-term use.
- If over-the-counter options fail: see a doctor. Prescription options exist, and so do causes that need a diagnosis.
What about “gut” supplements?
None of the video-marketed gut capsules we reviewed has been tested in a trial, and their total daily blends (0.5–1.5 g) are far below the fiber doses used in research. A capsule that promises to “empty your bowels” in 10 seconds isn’t on any guideline list. Details: Gut Save vs DigestiStart vs GutOptim.
Questions people ask
What relieves constipation the fastest?
A bisacodyl suppository, usually within 15 minutes to 1 hour. Magnesium citrate works within about 30 minutes to 6 hours, and stimulant tablets usually overnight.
Is MiraLAX or Dulcolax better?
They do different jobs. PEG (MiraLAX) works over 1–3 days and has a strong recommendation for chronic constipation. Bisacodyl (Dulcolax) works within hours and is recommended for short-term or rescue use.
What natural remedy works for constipation?
Kiwifruit (2–3 a day), rye bread, high-mineral water and psyllium have the best support in the 2025 BDA guideline. Expect results over days to weeks.
Can I take laxatives every day?
Over-the-counter labels say not to use them for more than a week without a doctor’s advice. For ongoing constipation, agree on a plan with your doctor; some options, such as PEG, are used long term under guidance.
Sources
- Chang L. et al. AGA–ACG Clinical Practice Guideline: Pharmacological Management of Chronic Idiopathic Constipation. Gastroenterology, 2023;164(7):1086–1106. PMC10542656
- Dimidi E. et al. British Dietetic Association guidelines for the dietary management of chronic constipation in adults. Journal of Human Nutrition and Dietetics, 2025;38(5):e70133. PubMed 41081513
- King’s College London. Kiwis could help manage chronic constipation (October 2025). kcl.ac.uk
- MiraLAX (polyethylene glycol 3350): consumer information. drugs.com
- Bisacodyl suppository and tablets: Drug Facts and consumer information. otclabels.com
- MedlinePlus. Psyllium. medlineplus.gov