Key results
We identified multiple herbal medicines that were effective in improving symptoms and well-being in people with functional dyspepsia. Also, they may not be associated with important unwanted events compared to sham treatment. However, we found little evidence on the comparative effectiveness of herbal medicines and other treatments.
The effect of herbal medicines may need to be compared to common medical treatments for functional dyspepsia to assess their relative effectiveness. More high-quality trials are needed for functional dyspepsia, especially with people with common gastrointestinal comorbidities.
Background
What is functional dyspepsia?
Functional dyspepsia is a frequent problem among adults. It is characterized by pain and discomfort in the stomach. However, unlike organic dyspepsia, these symptoms can not be blamed on ulcers or other lesions in the stomach or intestines.
How is functional dyspepsia treated?
The treatments for this include drug and non-drug approaches, but it is not known how well they work. A variety of herbal products have been tested, to an extent, as possible treatments for this condition.
What did we want to find out?
In this review, we looked at all available studies on this subject to find out if any of these herbs can improve symptoms and well-being, and if they are safe.
Study characteristics
What did we do?
We searched for studies investigating non-Chinese herbal medicines compared with usual treatment or other treatments in people with functional dyspepsia. We compared and summarized their results about symptoms, well-being, and unwanted effects, and rated our confidence in the evidence according to study methods and the numbers of people in the studies.
Summary of results
What did we find?
We found 41 studies of 4477 people with functional dyspepsia that assessed 27 herbal products. Most of them compared herbal products against placebo (dummy tablets), although some studies compared them against drugs like omeprazole, H pylori treatment, or other treatments. The duration of the studies varied from 15 days to 12 weeks. The studies were conducted in many countries around the world; 12 of them took place in Iran. The pharmaceutical industry provided funds for 14 studies, government institutions funded eight, a medical association funded one study and the rest did not state how they were funded.
Main results
STW5 (known commercially as Iberogast because one of the herbs it contains is Iberis amara L.) may reduce global symptoms of dyspepsia compared with placebo in one or two months. SWT5 may not be more effective than placebo in improving the well-being, but only one small study measured this. In terms of safety, unwanted effects may be similar when compared to placebo.
Peppermint and caraway oil probably result in a moderate to a large reduction in global symptoms of dyspepsia and improved well-being compared to a simulated treatment at one month. However, there may be little to no difference in the rate of unwanted effects between this intervention and the placebo.
Curcuma longa probably reduces global symptoms of dyspepsia and improves well-being compared to placebo at four weeks. There is probably little to no difference in the rate of unwanted effects between this intervention and placebo.
We found evidence that the following herbal medicines may improve symptoms of dyspepsia compared to placebo: Lafonesia pacari, Nigella sativa, artichoke, Boensenbergia rotunda, Pistacia lenticus, Enteroplant, Ferula asafoetida, ginger and artichoke, Glycyrrhiza glabra, OLNP- 06, red pepper, Cuadrania tricuspidata, jollab, and Pimpinella anisum. Mentha pulegium and cinnamon oil may provide little to no difference compared to placebo; moreover, Mentha longifolia may increase dyspeptic symptoms. Almost all the studies reported little to no difference in the rate of unwanted effects compared to placebo, except for red pepper, which may result in a higher risk of unwanted effects compared to placebo. Most studies did not report on participants' well-being.
When compared to other drugs, we only found that a combination of essential oils seems to provide superior relief of symptoms compared to omeprazole.
Certainty of the evidence
What are the limitations of the evidence?
We have little confidence in the evidence, as we found few trials for each herbal medicine, few participants for each comparison, and few head-to-head comparisons. In addition, most studies had limitations in their design. Besides, many studies did not clearly state how they diagnosed functional dyspepsia.
How up to date is this evidence?
The evidence is current to 22 December 2022.
Based on moderate to very low-certainty evidence, we identified some herbal medicines that may be effective in improving symptoms of dyspepsia. Moreover, these interventions may not be associated with important adverse events. More high-quality trials are needed on herbal medicines, especially including participants with common gastrointestinal comorbidities.
One-third of people with gastrointestinal disorders, including functional dyspepsia, use some form of complementary and alternative medicine, including herbal medicines.
The primary objective is to assess the effects of non-Chinese herbal medicines for the treatment of people with functional dyspepsia.
We searched the following electronic databases on 22 December 2022: Cochrane Central Register of Controlled Trials, MEDLINE, Embase, Allied and Complementary Medicine Database, Latin American and Caribbean Health Sciences Literature, among other sources, without placing language restrictions.
We included RCTs comparing non-Chinese herbal medicines versus placebo or other treatments in people with functional dyspepsia.
Two review authors independently screened references, extracted data and assessed the risk of bias from trial reports. We used a random-effects model to calculate risk ratios (RRs) and mean differences (MDs). We created effect direction plots when meta-analysis was not possible, following the reporting guideline for Synthesis without Meta-analysis (SWiM). We used GRADE to assess the certainty of the evidence (CoE) for all outcomes.
We included 41 trials with 4477 participants that assessed 27 herbal medicines. This review evaluated global symptoms of functional dyspepsia, adverse events and quality of life; however, some studies did not report these outcomes.
STW5 (Iberogast) may moderately improve global symptoms of dyspepsia compared with placebo at 28 to 56 days; however, the evidence is very uncertain (MD -2.64, 95% CI -4.39 to -0.90; I2 = 87%; 5 studies, 814 participants; very low CoE). STW5 may also increase the improvement rate compared to placebo at four to eight weeks' follow-up (RR 1.55, 95% CI 0.98 to 2.47; 2 studies, 324 participants; low CoE). There was little to no difference in adverse events for STW5 compared to placebo (RR 0.92, 95% CI 0.52 to 1.64; I2 = 0%; 4 studies, 786 participants; low CoE). STW5 may cause little to no difference in quality of life compared to placebo (no numerical data available, low CoE).
Peppermint and caraway oil probably result in a large improvement in global symptoms of dyspepsia compared to placebo at four weeks (SMD -0.87, 95% CI -1.15 to -0.58; I2 = 0%; 2 studies, 210 participants; moderate CoE) and increase the improvement rate of global symptoms of dyspepsia (RR 1.53, 95% CI 1.30 to 1.81; I2 = 0%; 3 studies, 305 participants; moderate CoE). There may be little to no difference in the rate of adverse events between this intervention and placebo (RR 1.56, 95% CI 0.69 to 3.53; I2 = 47%; 3 studies, 305 participants; low CoE). The intervention probably improves the quality of life (measured on the Nepean Dyspepsia Index) (MD -131.40, 95% CI -193.76 to -69.04; 1 study, 99 participants; moderate CoE).
Curcuma longa probably results in a moderate improvement global symptoms of dyspepsia compared to placebo at four weeks (MD -3.33, 95% CI -5.84 to -0.81; I2 = 50%; 2 studies, 110 participants; moderate CoE) and may increase the improvement rate (RR 1.50, 95% CI 1.06 to 2.11; 1 study, 76 participants; low CoE). There is probably little to no difference in the rate of adverse events between this intervention and placebo (RR 1.26, 95% CI 0.51 to 3.08; 1 study, 89 participants; moderate CoE). The intervention probably improves the quality of life, measured on the EQ-5D (MD 0.05, 95% CI 0.01 to 0.09; 1 study, 89 participants; moderate CoE).
We found evidence that the following herbal medicines may improve symptoms of dyspepsia compared to placebo: Lafonesia pacari (RR 1.52, 95% CI 1.08 to 2.14; 1 study, 97 participants; moderate CoE), Nigella sativa (SMD -1.59, 95% CI -2.13 to -1.05; 1 study, 70 participants; high CoE), artichoke (SMD -0.34, 95% CI -0.59 to -0.09; 1 study, 244 participants; low CoE), Boensenbergia rotunda (SMD -2.22, 95% CI -2.62 to -1.83; 1 study, 160 participants; low CoE), Pistacia lenticus (SMD -0.33, 95% CI -0.66 to -0.01; 1 study, 148 participants; low CoE), Enteroplant (SMD -1.09, 95% CI -1.40 to -0.77; 1 study, 198 participants; low CoE), Ferula asafoetida (SMD -1.51, 95% CI -2.20 to -0.83; 1 study, 43 participants; low CoE), ginger and artichoke (RR 1.64, 95% CI 1.27 to 2.13; 1 study, 126 participants; low CoE), Glycyrrhiza glaba (SMD -1.86, 95% CI -2.54 to -1.19; 1 study, 50 participants; moderate CoE), OLNP-06 (RR 3.80, 95% CI 1.70 to 8.51; 1 study, 48 participants; low CoE), red pepper (SMD -1.07, 95% CI -1.89 to -0.26; 1 study, 27 participants; low CoE), Cuadrania tricuspidata (SMD -1.19, 95% CI -1.66 to -0.72; 1 study, 83 participants; low CoE), jollab (SMD -1.22, 95% CI -1.59 to -0.85; 1 study, 133 participants; low CoE), Pimpinella anisum (SMD -2.30, 95% CI -2.79 to -1.80; 1 study, 107 participants; low CoE). The following may provide little to no difference compared to placebo: Mentha pulegium (SMD -0.38, 95% CI -0.78 to 0.02; 1 study, 100 participants; moderate CoE) and cinnamon oil (SMD 0.38, 95% CI -0.17 to 0.94; 1 study, 51 participants; low CoE); moreover, Mentha longifolia may increase dyspeptic symptoms (SMD 0.46, 95% CI 0.04 to 0.88; 1 study, 88 participants; low CoE).
Almost all the studies reported little to no difference in the rate of adverse events compared to placebo except for red pepper, which may result in a higher risk of adverse events compared to placebo (RR 4.31, 95% CI 1.56 to 11.89; 1 study, 27 participants; low CoE). With respect to the quality of life, most studies did not report this outcome.
When compared to other interventions, essential oils may improve global symptoms of dyspepsia compared to omeprazole. Peppermint oil/caraway oil, STW5, Nigella sativa and Curcuma longa may provide little to no benefit compared to other treatments.