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Prunes for Constipation: Do They Work and How Many to Eat?

Prunes are a classic home remedy for constipation. See what the trials found, the amounts studied, side effects like wind, and when to see a doctor.

Edited by Anmar ArabPublished 22 October 2026, 7 min read
On this page
  1. Quick answer
  2. What the research says
  3. How to use it
  4. Possible side effects and interactions
  5. Who should be careful
  6. When to see a doctor
  7. Frequently asked questions

Quick answer

Prunes are dried plums and a long-standing remedy for a sluggish bowel. The research behind them is small but fairly consistent.

  • They seem to help mild constipation. In a small trial of adults with long-term constipation, eating prunes increased the number of complete bowel movements per week, and worked at least as well as psyllium fibre.
  • They add bulk to stools. In healthy adults who ate little fibre, prunes increased daily stool weight and how often people went.
  • The evidence is limited. Only a handful of trials exist, they were small and short, and some were funded by industry. A recent expert review described prunes as something that "may be effective".
  • Expect some wind. Extra flatulence is the most common side effect, and prunes caused more bloating than kiwifruit or psyllium in pooled trials.

Prunes are a reasonable first step for mild constipation in adults, alongside fluids and movement, but not for constipation caused by medicines or an underlying condition.

What the research says

Prunes compared with psyllium (2011). Attaluri and colleagues, writing in Alimentary Pharmacology & Therapeutics, studied 40 adults with chronic constipation, almost all women. In a crossover design, each person ate six prunes twice a day for three weeks and, in a separate three-week period, took psyllium fibre (about 6 g of fibre a day). Complete spontaneous bowel movements rose from an average of 1.7 a week at the start to 3.5 a week with prunes and 2.8 a week with psyllium. Stool consistency improved with both. The trial was not blinded, it was small, and it was funded by industry. A summary in American Family Physician judged prunes at least as effective as psyllium.

Prunes in people who were not constipated (2019). Lever and colleagues, in Clinical Nutrition, randomly assigned 120 healthy adults with a low fibre intake to eat 80 g or 120 g of prunes a day, or to drink water only, for four weeks. Stool weight rose by an average of about 22 g a day with 80 g of prunes and 33 g a day with 120 g, compared with almost no change in the control group. Stool frequency also increased, most clearly in the 80 g group. Stool consistency and gut transit time did not change significantly. The study was part of a PhD funded by the California Dried Plum Board, although the authors state the funder had no role in the research.

The bigger picture. A 2025 review in the Proceedings of the Nutrition Society by Dimidi looked at prunes alongside other dietary approaches. A meta-analysis it describes found only two trials comparing whole prunes with psyllium. Prunes performed about as well for softening stools and reducing straining, but the softening result was not statistically significant. The same analysis found that kiwifruit and psyllium caused fewer reports of bloating than prunes, and kiwifruit caused less tummy pain. Prunes appear in very few national constipation guidelines. The 2025 British Dietetic Association guidelines, based on systematic reviews of 75 trials, included statements on prunes, but rated the evidence behind most of its 59 statements as low or very low certainty.

Why they might work. Prunes contain about 6 g of fibre per 100 g, plus sorbitol, a naturally occurring sugar alcohol. Researchers are not yet sure which of these, or which plant compounds, is responsible. The NHS lists fruits containing sorbitol among its self-help tips for constipation.

How to use it

The amounts below are the ones tested in studies, not official doses.

  • Amounts studied: six prunes twice a day in the constipation trial, and 80 g or 120 g a day in the trial of healthy adults.
  • Start low and increase slowly. The NHS advises increasing fibre gradually when constipated.
  • Drink enough fluid. The NHS advises drinking plenty of water and other fluids and avoiding alcohol when constipated. Participants in the 2019 trial also drank 300 ml of water a day with their prunes.
  • Give it time. The trials ran for three to four weeks, so a fair test is a few weeks, not one day.
  • Eat them with meals. The NHS advises eating dried fruit at mealtimes rather than as a snack between meals, to reduce the risk of tooth decay.
  • Keep other habits going. The NHS also recommends regular activity and not ignoring the urge to go.

Prune juice is another option. One trial found 54 g a day softened stools compared with a control drink, though it did not change how often people went. The NHS suggests keeping fruit juice to 150 ml a day in total, again taken with meals, because juice releases sugars that can harm teeth.

Prunes are a food, not a medicine. If you have blood in your stool, unexplained weight loss, ongoing tummy pain or a sudden change in your bowel habits, see a doctor rather than trying to manage it with diet alone.

Possible side effects and interactions

  • Wind: In the 2019 trial, people eating prunes reported moderate or severe flatulence on more days per week than the control group.
  • Bloating and tummy pain: Pooled trial data showed more bloating with prunes than with kiwifruit or psyllium, and more tummy pain than with kiwifruit.
  • Acid reflux: The 2019 trial found a higher rate of reflux symptoms with prunes in one planned comparison.
  • Calories: A dozen prunes provide around 260 calories, according to American Family Physician, compared with 50 to 90 calories for a tablespoon of psyllium. Prunes have a low glycaemic index, and the 2019 trial found no weight gain over four weeks.
  • Teeth: As with all dried fruit, frequent snacking between meals raises the risk of tooth decay.

No important drug interactions with prunes as a food were reported in the sources reviewed here.

Who should be careful

  • People prone to bloating: prunes caused more bloating than other options in trials, so kiwifruit or psyllium may suit some people better. A doctor or dietitian can help.
  • People watching their energy or sugar intake, including those with diabetes: prunes are energy-dense, so it helps to count them as part of meals and check with your care team if you are unsure.
  • People whose constipation is caused by a medicine, such as opioid painkillers: the NHS advises seeing a GP, and you should not stop a prescribed medicine without advice.
  • Children: the studies were in adults, so ask a doctor or pharmacist about constipation in children.

When to see a doctor

The NHS advises seeing a GP if:

  • your constipation is not improving with treatment, or keeps coming back
  • you are regularly bloated
  • you have blood in your poo
  • you have lost weight without trying
  • you feel constantly tired as well as constipated
  • you think a medicine you take is causing it
  • your bowel habits change suddenly, or you have tummy pain

A pharmacist can also suggest a suitable laxative if diet changes have not helped.

Frequently asked questions

How quickly do prunes work for constipation?

The trials measured results over three to four weeks of daily eating. If there is no improvement after a few weeks of prunes, fluids and activity, speak to a pharmacist or doctor.

Are prunes better than psyllium or kiwifruit?

In one small trial, prunes increased bowel movements a little more than psyllium. Overall, though, the evidence suggests they are roughly comparable, and expert reviewers say it has not been shown that one is clearly better. Kiwifruit and psyllium caused less bloating than prunes in pooled data.

Is prune juice as good as whole prunes?

Prune juice has been studied less. One trial found it softened stools but did not increase how often people went. Whole prunes also keep their fibre. If you choose juice, keep portions modest and drink it with a meal to protect your teeth.

References

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