Ranked by evidence
Best supplements for constipation
For constipation, the supplements that work are plain and cheap: gel-forming fibre such as psyllium, and osmotic magnesium. Everything below is ranked by the evidence for constipation specifically, not by popularity, and stimulant laxatives are labelled for the short-term use they suit.
Picks are ranked by the strength of published evidence for this goal in otherwise healthy adults. A persistent symptom needs a clinician's evaluation, and no supplement on this list replaces treatment.
Evidence last reviewed: September 2026
Top picks
| Option | Evidence | Best for | The honest note | |
|---|---|---|---|---|
| Psyllium Husk (fiber) | Strong evidence | chronic constipation, first line | A gel-forming bulk fibre that consistently improves stool frequency and consistency, and a first-line recommendation in clinical guidelines. Take 5–10 g a day with plenty of water, starting low to limit bloating. | View |
| Magnesium Citrate | Moderate evidence | a reliable osmotic laxative | Citrate draws water into the bowel, which is why concentrated solutions are used for colonoscopy prep. Loose stools begin for many people above 300–400 mg of elemental magnesium a day; discuss it with a clinician if you have kidney disease. | View |
Solid options
| Option | Evidence | Best for | The honest note | |
|---|---|---|---|---|
| Magnesium Oxide | Moderate evidence | a cheap daily laxative | In a placebo-controlled trial, 0.5 g three times daily improved chronic constipation in 70.6% of women versus 25.0% on placebo. If you use laxative doses long term, have your magnesium levels checked, especially with impaired kidney function. | View |
| Ground Flaxseed | Moderate evidence | a food-based fibre option | Randomized trials found it improved functional constipation, performing comparably to psyllium in smaller trials. Studies used 10–30 g of ground seed a day, taken with plenty of water. | View |
| Partially Hydrolyzed Guar Gum | Moderate evidence | fibre that dissolves without thickening | Small randomized trials support it for constipation and stool form. Trials report little gas and bloating compared with inulin, though this comes from adverse-event reports rather than head-to-head studies. | View |
| Bifidobacterium Lactis (BB-12/HN019) | Moderate evidence | slow gut transit | The HN019 strain shortened colonic transit time in constipated adults in dose-ranging and multicentre trials. Effects are consistent but modest, and they belong to the strains tested. | View |
| Inulin (Prebiotic Fiber) | Moderate evidence | a gentle prebiotic top-up | It softens and speeds up stool, but only by roughly half an extra bowel movement a week, less than psyllium. As a FODMAP it often causes gas and worsens IBS symptoms. | View |
Situational
Popular for this goal — but the evidence says skip
- Fiber Gummies Limited evidence
A typical serving supplies 3–5 g of inulin, well below the 10–20 g a day of supplemental fibre used in constipation trials, and inulin is the weaker fibre for constipation.
- Colon Cleanse Formulas Limited evidence
A systematic review found no credible evidence of benefit from colon cleansing and a documented list of harms; the psyllium inside is the only genuinely useful part.
- Triphala Limited evidence
There are no adequately powered placebo-controlled trials in functional constipation, and its anthraquinone content makes it unsuitable for prolonged daily use.
- Aloe Vera Moderate evidence
Controlled data for constipation are a handful of small trials with mixed results, and the FDA removed aloe latex from over-the-counter laxatives in 2002 for lack of safety data.
- Chia Seed Limited evidence
It gels like other fibres, but no randomized trial has tested chia for constipation or stool form as a primary outcome.
- Acacia Fiber (Gum Arabic) Limited evidence
Well tolerated, but its evidence for bowel regularity comes from small, underpowered trials, and its bulking effect is modest compared with psyllium.
Our verdict
Start with psyllium, taken daily with plenty of water; if that is not enough, magnesium citrate or magnesium oxide is the next step. Skip fibre gummies, colon cleanses, triphala and aloe, which are sold hard for regularity and have little evidence for it.