Index of Herbs

Concern guide

Herbs for Constipation

Fiber and herbal laxatives for constipation, from psyllium and senna to flaxseed, with what the research shows and when to get help.

5 herbs reviewed

Updated October 9, 2026

Constipation means having fewer than three bowel movements a week, or stools that are hard, dry, lumpy, or difficult or painful to pass, sometimes with a feeling that not everything has come out. It is common at every age, and more so in pregnancy and in older adults, and changes in routine, travel, too little fiber or fluid, and many medicines can bring it on, opioid painkillers above all. Most bouts are short-lived and respond to simple changes, but constipation that keeps coming back, or a change in bowel habit that lasts, deserves a closer look.

Fiber, fluids, and regular meals and activity come first, and the 2023 guideline from the American Gastroenterological Association and the American College of Gastroenterology (AGA–ACG) suggests fiber supplements as a first step for chronic constipation. Herbs sit on both sides of the laxative shelf. Psyllium and flaxseed are bulk-forming: their soluble fiber soaks up water to soften and bulk up stool, usually within a day or so, and suits regular use. Senna and aloe latex are stimulant laxatives that push the bowel into action overnight; the guideline suggests senna as an inexpensive, widely available option, but both are meant for short courses, and EMA limits self-treatment to one week. When these are not enough, the guideline strongly recommends medicines such as polyethylene glycol, so a doctor or pharmacist is the next step rather than a stronger herb.

The herbs below are ordered by strength of evidence for constipation, then by how commonly they are used. Ratings run from good clinical evidence to long traditional use, and constipation is one of the few concerns where herbs have mainstream backing: psyllium and senna both feature in the gastroenterology guideline. Flaxseed has small but encouraging trials, aloe latex is accepted in the EU on the strength of pharmacology and long use rather than trials but has been dropped by US regulators, and slippery elm rests on tradition. The safety section covers the warning signs that need a doctor and why stimulant laxatives are not daily supplements.

02 The shortlist

The herbs, from best studied to time-honored

How to read the ratings

  • Good clinical evidence
  • Promising clinical evidence
  • Early or mixed evidence
  • Long traditional use

Ratings show how much research backs each herb for this particular concern. Every herb links to its full monograph, with preparations, safety notes, and sources.

  1. 01 Psyllium

    Good clinical evidence

    Plantago ovata

    Psyllium husk is a gel-forming soluble fiber, and the AGA–ACG guideline suggests fiber as a first step for chronic constipation, noting that among fibers psyllium appears to be the one that works. In a 2022 meta-analysis of 16 trials in 1,251 adults, 66% responded to fiber supplements versus 41% on control, with psyllium working best above 10 g a day for at least four weeks. EMA accepts the husk as a well-established medicine for habitual constipation. Wind and bloating are common at first; take each gram with at least 30 ml of liquid, apart from medicines.

    Read the psyllium monograph →

  2. 02 Senna

    Good clinical evidence

    Senna alexandrina

    Senna leaf and pod contain sennosides, which gut bacteria activate in the colon to speed transit and draw water into the stool, usually bringing a bowel movement overnight. The 2023 AGA–ACG guideline suggests senna for chronic constipation and calls it an attractive first-line option, given its low cost and availability, after a 90-person trial in which senna and magnesium oxide each beat placebo over four weeks. EMA accepts it for short-term occasional constipation. Cramping is common, and most trial participants lowered their dose. Without medical advice, use it for no more than one week.

    Read the senna monograph →

  3. 03 Flaxseed

    Promising clinical evidence

    Linum usitatissimum

    Flaxseed, or linseed, is a gentle bulk-forming laxative: its mucilage swells with water to soften and bulk up stool, and EMA accepts it as a well-established medicine for habitual constipation. In a four-week trial of 90 adults, flaxseed flour raised weekly bowel movements from two to seven, slightly more than lactulose, and in 77 people with type 2 diabetes it did at least as well as psyllium, though trials so far are small and not fully blinded. It usually works within 12 to 24 hours. Take each dose with at least 150 ml of liquid, apart from medicines, and avoid it with swallowing problems or a narrowed gut.

    Read the flaxseed monograph →

  4. 04 Aloe Vera

    Early or mixed evidence

    Aloe vera

    Aloe latex, the bitter yellow sap under the leaf skin, is a stimulant laxative that works much like senna, and EMA accepts a standardized dried leaf-juice extract for short-term occasional constipation from age 12, for no more than a week and only after diet changes or fiber have failed. The FDA took aloe out of US over-the-counter laxatives in 2002 because the safety data it asked for were never submitted, and whole-leaf extract, which caused intestinal tumors in rats when not decolorized, is classed by IARC as possibly carcinogenic to humans. Clear aloe gel drinks are a different product. Avoid aloe latex in pregnancy and breastfeeding.

    Read the aloe vera monograph →

  5. 05 Slippery Elm

    Long traditional use

    Ulmus rubra

    Slippery elm inner bark forms a soft gel in water, and several Native American nations, including the Dakota and Omaha-Ponca, drank it as a laxative. Memorial Sloan Kettering notes that its fiber is thought to act as a bulk-forming laxative, but this has not been measured in controlled trials; the only clinical data come from a small uncontrolled pilot in which a blend of slippery elm, lactulose, oat bran, and licorice increased bowel movements in 10 people with constipation-predominant IBS. Take it apart from medicines, and choose cultivated bark.

    Read the slippery elm monograph →

03 Caution

Using these herbs safely

Constipation is usually harmless, but some signs need a doctor rather than a laxative. See a doctor right away if constipation comes with bleeding from the rectum or blood in the stool, constant belly pain, being unable to pass gas, vomiting, fever, lower back pain, or weight loss without trying. Book an appointment if constipation is not improving with treatment or keeps coming back, if you are regularly bloated or tired all the time, if a medicine such as an opioid painkiller seems to be the cause, or if your bowel habits have changed suddenly; a family history of bowel cancer is another reason to ask. Black or dark red stools or bloody diarrhea need urgent advice. In older people and people with dementia, constipation can be missed and may show up as new confusion. Stop any laxative and ask a doctor if there is rectal bleeding or no bowel movement after using it.

Stimulant laxatives such as senna and aloe latex are not first-line: NIDDK advises them only when constipation is severe or other treatments have not worked, and people who have relied on them long term should ask a doctor how to stop gradually. Long-term or heavy use can lower potassium, which strengthens the effect of digoxin and is risky with some heart-rhythm medicines, and diuretics, corticosteroids, and licorice root add to the loss. Psyllium and flaxseed can slow the absorption of medicines taken at the same time, so take them half an hour to an hour apart; EMA lists minerals, vitamin B12, digoxin, warfarin, carbamazepine, and lithium for psyllium, and advises medical supervision when bulk-forming fiber is combined with opioids or loperamide, which raise the risk of blockage. Stacking aloe, senna, and magnesium products multiplies cramping and electrolyte stress, so use one laxative at a time.

Some situations rule these herbs out. EMA contraindicates senna and aloe laxatives with bowel obstruction or narrowing, inflammatory bowel disease such as Crohn’s disease or ulcerative colitis, appendicitis, belly pain of unknown cause, and severe dehydration. Psyllium and flaxseed swell as they absorb water, so they must always be taken with plenty of liquid, at least 30 ml per gram of psyllium and 150 ml with each dose of linseed; dry fiber can block the throat, esophagus, or bowel, so these are not suitable for people with swallowing problems or a narrowed gut, and chest pain, vomiting, or trouble swallowing or breathing after a dose needs urgent help. Psyllium can also cause allergy, including asthma and, rarely, anaphylaxis, especially in people who handle the powder often. For laxative use EMA describes whole or broken linseed, and Germany’s Federal Institute for Risk Assessment advises adults to keep raw ground linseed to about 15 to 20 g a day because it releases small amounts of cyanide.

Pregnancy and breastfeeding: EMA contraindicates senna and aloe laxatives and does not recommend medicinal linseed, while it says psyllium husk may be considered if a change of diet has not worked; the NHS is more permissive about senna, saying it can usually be taken after speaking to a pharmacist or doctor, and slippery elm has no safety data. Children: EMA contraindicates senna and aloe laxatives under 12, and in the UK senna is prescription-only at that age; medicinal linseed is not recommended under 12 and psyllium under 6. Young children who swallowed senna laxatives by accident have developed severe diaper rash and blistering, so keep them out of reach, and constipation in a child deserves a doctor’s advice. Older adults should not usually take senna long term. Finally, laxatives do not cause meaningful calorie loss, and using senna “detox” or slimming teas for weight control is dangerous.

04 Questions

Frequently Asked Questions

For most people, start with fiber. Psyllium husk is the best-supported herbal fiber: the AGA–ACG guideline suggests fiber first for chronic constipation, and among fibers psyllium appears to be the one that works. If fiber and fluids are not enough, senna is a stimulant laxative the same guideline suggests as an inexpensive option, though EMA limits self-treatment to a week. Flaxseed is a gentler bulk-forming alternative with small, encouraging trials. Constipation that keeps coming back is worth discussing with a doctor.

Not without medical advice. EMA and US labels limit self-treatment with senna to one week, and the NHS says to see a doctor if constipation has not improved after three days. Long-term use can cause low potassium and dependence on laxatives, and the AGA–ACG guideline notes there are no long-term safety studies of senna in humans. Fiber such as psyllium, taken with plenty of fluid, is the usual first step, and a doctor can supervise longer-term treatment if it is needed.

There is not enough evidence to pick a winner. Both are bulk-forming fibers that EMA accepts as well-established medicines for habitual constipation. In the only head-to-head trial, 77 people with type 2 diabetes ate 10 g of flaxseed or psyllium in cookies twice a day for 12 weeks; both beat placebo and flaxseed appeared to do better, but the study was small and single-blind. Psyllium has far more trials behind it overall. Whichever you choose, take it with plenty of liquid and apart from medicines.

It depends which part of the plant is in the bottle. Clear inner-leaf aloe vera gel is mainly a skin product, while the yellow latex under the leaf skin contains aloin, a stimulant laxative that can cause cramps, diarrhea, and potassium loss. EMA accepts a standardized latex extract for up to a week of occasional constipation, but the FDA removed aloe from US over-the-counter laxatives in 2002, and whole-leaf juices do not always say whether they have been decolorized to remove the latex. Fiber or senna are better-studied choices.

Not for weight loss. Many “detox,” “cleanse,” and slimming teas contain senna, a stimulant laxative, so they mostly cause loose stools and cramps. Laxatives do not cause meaningful calorie loss, and misusing them for weight control is dangerous, because it can drain potassium and lead to reliance on laxatives. If you want a gentle daily aid for regularity, a fiber such as psyllium taken with plenty of water is a far safer choice.

See a doctor right away if constipation comes with blood in your stool or from the rectum, constant belly pain, being unable to pass gas, vomiting, fever, lower back pain, or unexplained weight loss. Make an appointment if it is not improving with treatment, keeps coming back, follows a new medicine, or marks a sudden change in your bowel habits, or if bowel cancer runs in your family. Fiber such as psyllium is a sensible first step meanwhile, and laxatives such as senna should not be needed for more than a few days at a time without advice.

05 References

Sources

These references support the claims in this guide. Each herb’s monograph carries its own full source list.

  1. American Gastroenterological Association-American College of Gastroenterology Clinical Practice Guideline: Pharmacological Management of Chronic Idiopathic Constipation

    Gastroenterology (PubMed 37211380), 2023

    Supports the good ratings for psyllium and senna: fiber as first-line therapy, with psyllium the fiber that appears effective; a conditional recommendation for senna as an attractive first-line option; and strong recommendations for polyethylene glycol and other medicines.

  2. The effect of fiber supplementation on chronic constipation in adults: an updated systematic review and meta-analysis of randomized controlled trials

    American Journal of Clinical Nutrition (PubMed 35816465), 2022

    Supports the good rating for psyllium: 16 trials with 1,251 adults, 66% responding to fiber versus 41% to control, with psyllium most effective above 10 g a day for at least four weeks, and more flatulence with fiber.

  3. Senna Versus Magnesium Oxide for the Treatment of Chronic Constipation: A Randomized, Placebo-Controlled Trial

    American Journal of Gastroenterology (PubMed 32969946), 2021

    Supports the good rating for senna: in 90 adults with chronic idiopathic constipation, overall improvement after 28 days was 69.2% on senna, 68.3% on magnesium oxide, and 11.7% on placebo.

  4. European Union herbal monograph on Senna alexandrina Mill. (Cassia senna L.; Cassia angustifolia Vahl), folium (Revision 1)

    European Medicines Agency (EMA/HMPC/625849/2015), 2020

    Well-established use of senna leaf for short-term occasional constipation, the one-week limit, potassium interactions, and contraindications including bowel obstruction, inflammatory bowel disease, pregnancy, breastfeeding, and children under 12.

  5. European Union herbal monograph on Linum usitatissimum L., semen

    European Medicines Agency (EMA/HMPC/377675/2014), 2015

    Supports the some rating for flaxseed: well-established use for habitual constipation with 150 ml of liquid per dose, onset in 12 to 24 hours, choking and obstruction warnings, spacing from medicines, and no use under 12 or in pregnancy.

  6. Effect of flaxseed or psyllium vs. placebo on management of constipation, weight, glycemia, and lipids: A randomized trial in constipated patients with type 2 diabetes

    Clinical Nutrition ESPEN (PubMed 30661699), 2019

    The 77-patient, single-blind trial in which 10 g of flaxseed or psyllium twice daily for 12 weeks both improved constipation more than placebo, with flaxseed appearing superior.

  7. European Union herbal monograph on Aloe barbadensis Mill. and on Aloe (various species, mainly Aloe ferox Mill. and its hybrids), folii succus siccatus

    European Medicines Agency, 2016

    Supports the mixed rating for aloe: well-established use of a standardized dried leaf juice for short-term occasional constipation from age 12, for up to one week, with contraindications in pregnancy, breastfeeding, and bowel disease.

  8. Status of Certain Additional Over-the-Counter Drug Category II and III Active Ingredients (final rule)

    US Food and Drug Administration, Federal Register, 2002

    The rule that found aloe and cascara sagrada not generally recognized as safe and effective as over-the-counter stimulant laxatives because requested safety data were never submitted.

  9. Symptoms & Causes of Constipation

    National Institute of Diabetes and Digestive and Kidney Diseases (NIH), 2018

    Source for the symptoms of constipation, medicines as a cause, and the signs that need a doctor right away, including rectal bleeding, constant pain, inability to pass gas, vomiting, fever, lower back pain, and unexplained weight loss.

  10. Treatment for Constipation

    National Institute of Diabetes and Digestive and Kidney Diseases (NIH), 2018

    Supports reserving stimulant laxatives for severe constipation or when other treatments have failed, and asking a doctor how to stop slowly after long-term use.

  11. Constipation

    NHS, 2023

    Source for when to see a GP, including constipation that is not improving, regular bloating, tiredness, medicine-induced constipation, and a sudden change in bowel habits, and for constipation being missed in older people and people with dementia.

  12. Bowel cancer symptoms

    NHS, 2024

    Supports the advice to get urgent help for black or dark red stools or bloody diarrhea, and to see a GP about changes in bowel habit, blood in stools, or unexplained weight loss.

  13. Senna

    MedlinePlus Drug Information, National Library of Medicine (NIH), 2024

    Supports the one-week limit, dependence with continued use, spacing from other medicines, and the caution that older adults should not usually take senna long term.

  14. Skin breakdown and blisters from senna-containing laxatives in young children

    Annals of Pharmacotherapy (PubMed 12708936), 2003

    Source for severe diaper rash and blistering after accidental ingestion of senna laxatives by children under 5.

  15. Laxative abuse: epidemiology, diagnosis and management

    Drugs (PubMed 20687617), 2010

    Supports the statement that laxatives do not cause meaningful calorie loss and that misusing them for weight control is dangerous.

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