Colon irritable

Peppermint

Mentha x piperita

A 2019 meta-analysis of 12 randomised trials (835 patients) found enteric-coated peppermint oil better than placebo for global IBS symptoms (number needed to treat about 3) and abdominal pain (about 4). A 2021 American College of Gastroenterology guideline recommends it; EMA grants well-established use.

Psyllium (Blond plantain)

Plantago ovata

A 2014 meta-analysis of 14 trials (906 patients) found soluble fibre helped IBS (about 1 in 7 treated benefited) while bran did not. EMA lists it as an adjuvant in constipation-predominant IBS.

Artichoke

Cynara cardunculus

Evidence comes from post-marketing surveillance: in a subgroup of 279 people with irritable bowel symptoms taking the extract for 6 weeks, symptoms fell significantly. There was no placebo comparison.

Asafoetida

Ferula assa-foetida

A 2020 meta-analysis of double-blind trials of Western herbal medicines found asafoetida reduced global IBS symptoms and was one of the few herbs with a replicated positive result. A 2019 Cochrane review counted two IBS-with-constipation trials of homeopathic asafoetida and rated that evidence very low certainty.

Bael

Aegle marmelos

In a 1989 Indian double-blind trial in 169 people with irritable bowel syndrome, an Ayurvedic preparation of bael plus Bacopa monnieri helped 64.9% over 6 weeks against 32.7% on placebo (standard drugs 78.3%); it worked best in diarrhoea-predominant IBS but did not prevent relapse over 6 months. Bael alone was not tested.

Caraway

Carum carvi

The same 2023 review describes favourable but less rigorous results for the peppermint–caraway oil combination in irritable bowel syndrome, and an uncontrolled 2026 single-arm study in 126 patients with abdominal pain or bloating reported symptom improvement over 8 weeks.

Cumin

Cuminum cyminum

An uncontrolled Iranian case series (about 57 patients, 50 analysed) found less pain, bloating and urgency with 20 drops a day of a 2% cumin-oil drop for 4 weeks; without a placebo group the effect cannot be separated from natural improvement. Five patients stopped because of severe nausea, pain or no benefit.

Kiwifruit

Actinidia chinensis var. deliciosa

In the same RCT, people with constipation-predominant irritable bowel syndrome gained about 1.7 complete bowel movements per week and reported better abdominal comfort.

Patchouli

Pogostemon cablin

In a 14-hospital double-blind RCT (212 adults with diarrhoea-predominant IBS), 20 ml Huoxiang Zhengqi oral liquid twice daily for 4 weeks raised the adequate-relief rate by 29 percentage points over placebo, with a small reduction in symptom severity; no serious adverse events.

Sangre de grado

Croton lechleri

In a 12-week trial in 240 women with diarrhoea-predominant IBS, crofelemer did not beat placebo on the primary pain endpoint; only a post-hoc analysis favoured it.

Wild thyme

Thymus serpyllum

In a randomised trial in 40 overweight adults with functional gut disorders, 600 mg of an aqueous extract before breakfast for eight weeks improved gastrointestinal symptoms and stool frequency; anti-inflammatory and pain-relieving effects were also seen in a rat model of IBS. A single small trial.

Wu yao

Lindera aggregata

A water extract (5.4 g/kg) reduced diarrhoea and visceral sensitivity in a rat model of diarrhoea-predominant IBS.

Deadly nightshade

Atropa bella-donna

Commission E approved standardised belladonna leaf preparations for spasms and colicky pain of the gut and bile ducts; in Germany these are prescription-only and the leaf may not be sold as a traditional herbal product.

Bread wheat

Triticum aestivum

In a BMJ meta-analysis, five trials of bran (221 patients) showed no benefit for irritable bowel syndrome (54% had persistent symptoms with bran and with control); the fibre benefit was confined to ispaghula (psyllium).

Fumitory

Fumaria officinalis

In a randomised, double-blind, placebo-controlled trial in 106 people with irritable bowel syndrome (Brinkhaus 2005), 1500 mg powdered fumitory daily for 18 weeks did no better than placebo for pain or bloating.