A Phase 1/2 interventional study of Artemisia Annua Leaf and placebo in Small Intestinal Bacterial Overgrowth Syndrome (SIBO), sponsored by National University of Natural Medicine. Recruiting at 1 site in United States. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2025-06-04.
Sponsored by National University of Natural Medicine · Phase 1/2, Interventional, and Other
Small intestinal bacterial overgrowth (SIBO) can cause symptoms like bloating, stomach pain, and changes in bowel movements, significantly affecting quality of life. Many people with irritable bowel syndrome (IBS) also have SIBO, and there is growing recognition of how important it is to address this condition. Artemisia annua has shown potential in managing SIBO based on early reports and studies suggesting it can fight bacteria like *E. coli* and *Klebsiella*, which are linked to a type of SIBO that produces hydrogen gas.
This study aims to test if Artemisia annua is safe and well-tolerated for adults with hydrogen-type SIBO. Over five weeks, participants will take either 5 grams of dried Artemisia annua leaves or a placebo. Researchers will monitor safety through blood tests, vital signs, and adverse events, and they will assess symptom changes using questionnaires and breath tests.
The trial will include up to 32 participants from the Portland, Oregon area. Participants will be randomly assigned to treatment groups, and neither they, the researchers, nor the test administrators will know who is receiving the herb or the placebo. Results will be analyzed using standard statistical methods.
This study addresses the lack of research on herbal treatments for SIBO. If successful, the findings could lead to larger studies and help expand treatment options for people with SIBO.
Background: Small intestinal bacterial overgrowth (SIBO) often leads to bloating, abdominal pain, and stool change, and has significant impacts on quality of life. There is a high prevalence of SIBO among irritable bowel syndrome patients in particular and a growing awareness in the medical community of the impact of this condition. Anecdotal reports indicate that Artemisia annua, traditionally used against malaria, has shown promise in individuals with SIBO and previous studies suggest it has antimicrobials effects against E. coli and Kelbsiella, the bacteria associated with the hydrogen subtype of SIBO. This protocol describes the design of a phase II triple blind placebo controlled trial aiming to evaluate the safety and tolerability of 5g a day of dried leaf Artemisia annua in treating adults with hydrogen subtype SIBO over a 5 week period. Secondary objectives include the impact on symptom severity and exploratory outcomes include hydrogen and methane gas response.
Methods: A triple-blind, placebo-controlled, parallel-arm trial will enroll up to 32 participants from the Portland Oregon metropolitan area. Participants will undergo two lactulose breath tests, biweekly blood tests, and regular symptom assessments. Randomization will be computer-generated, stratified by symptom severity, with adherence closely monitored. Outcomes will measure changes in laboratory toxicology indicators, vital statistics, adverse events, and symptom severity. Data will be analyzed using appropriate statistical tests with a significance level set at p\<.05.
Discussion: This is a protocol for a phase II trial of Artemisia annua in individuals with hydrogen subtype SIBO. This study helps address the dearth of formal studies of herbal treatments for SIBO and the results could provide a basis for larger trials and contribute to broader treatment strategies for this condition.
11 studies on the registry are indexed under Blind Loop Syndrome; 4 are open to participants now.
This study's planned enrollment of 32 is below the median of 48 across 10 interventional studies indexed under Blind Loop Syndrome.
Browse Blind Loop Syndrome studies →National University of Natural Medicine is the lead sponsor of 39 studies on the registry; 8 are open to participants now.
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Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
CYP3A is a group of enzymes, mainly CYP3A4, in the liver and gut that break down many medicines. Some medicines, supplements and foods (grapefruit, St John’s wort) slow them down or speed them up, which changes how much of a study drug stays in the body.
Studies list them so they can be avoided or switched; bring a list of everything you take, including supplements.
GFR (glomerular filtration rate) is how much blood the kidneys filter each minute. It is usually estimated from a blood test — eGFR, by formulas such as CKD-EPI or MDRD — and some studies ask for it to be measured directly instead. Usually given in mL/min/1.73 m².
Check the method, the units and the minimum the study states. A value of 90 or above is in the normal-or-high range, but kidney damage can show in other tests too.
Two enzymes measured in a routine blood test of the liver. Higher levels can mean the liver is under strain or damaged. SGPT and SGOT are older names for ALT and AST.
Criteria usually give a limit as a multiple of the upper limit of normal (ULN), often higher when cancer has spread to the liver.
A yellow substance made when red blood cells are broken down, which the liver clears. A high level can mean a problem with the liver or the bile ducts.
Criteria often allow more for people with Gilbert’s syndrome, a harmless inherited condition that raises bilirubin.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Childbearing potential
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraception
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
CYP3A (CYP3A4) inhibitors and inducers
CYP3A is a group of enzymes, mainly CYP3A4, in the liver and gut that break down many medicines. Some medicines, supplements and foods (grapefruit, St John’s wort) slow them down or speed them up, which changes how much of a study drug stays in the body.
Studies list them so they can be avoided or switched; bring a list of everything you take, including supplements.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
GFR and eGFR (kidney filtering)
GFR (glomerular filtration rate) is how much blood the kidneys filter each minute. It is usually estimated from a blood test — eGFR, by formulas such as CKD-EPI or MDRD — and some studies ask for it to be measured directly instead. Usually given in mL/min/1.73 m².
Check the method, the units and the minimum the study states. A value of 90 or above is in the normal-or-high range, but kidney damage can show in other tests too.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ALT and AST (liver enzymes)
Two enzymes measured in a routine blood test of the liver. Higher levels can mean the liver is under strain or damaged. SGPT and SGOT are older names for ALT and AST.
Criteria usually give a limit as a multiple of the upper limit of normal (ULN), often higher when cancer has spread to the liver.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Bilirubin
A yellow substance made when red blood cells are broken down, which the liver clears. A high level can mean a problem with the liver or the bile ducts.
Criteria often allow more for people with Gilbert’s syndrome, a harmless inherited condition that raises bilirubin.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Dietary Supplement: Artemisia Annua Leaf
We have chosen dried-leaf alfalfa of equal weight and dosing to the interventional product (5 grams, 15 caps, 5/am, 5/noon, 5/pm for the 4 weeks of the intervention period plus an additional 1 week dose escalation period to match the dosing of the Artemisia product). We have chosen this as a comparator in consultation with SIBO and herbal medicine content experts as alfalfa matches the texture and color of Artemisia annua and, in the doses used, will provide no meaningful amounts of FODMAPs or antimicrobial phytochemicals. The alfalfa will be sourced from Bulk Apotherapy, LCC, and encapsulated at the same facility as the Artemisia capsules. Containers of placebo capsules will be kept in a secured cabinet before being administered, under climate-controlled conditions, and checked weekly to ensure consistent ambient temperature.
Other: placebo
The intervention is Artecinua™ which is an organic Artemisia annua dried leaf powder in a vegan / kosher/ halal capsule. Artemisia annua L is classified as a 'generally regarded as safe' (GRAS) herb. Participants will be instructed to wean up to a full 5g dose by the following schedule. 1. gram (3 caps) 1st day, 2. grams (6 caps) 3/am, 3/pm, for the 3rd day, 3. grams (9 caps) 3/am 3/noon 3/pm for the 5th day, 4. grams (12 caps) 4/am, 4/noon, 4/pm for the 7th day, 5. grams (15 caps) 5/am, 5/noon, 5/pm for rest of intervention period (4 weeks) Containers of ArtecinuaTM will be kept in a secured cabinet before being administered, under climate-controlled conditions, and checked weekly to ensure consistent ambient temperature. The justification of the 5g a day dosing is based on empiric experience and is in line with recommended dosages by the pharmacopeia of the People's Republic of China and has been previously used in clinical trials
We have chosen dried-leaf alfalfa of equal weight and dosing to the interventional product (5 grams, 15 caps, 5/am, 5/noon, 5/pm for the 4 weeks of the intervention period plus an additional 1 week dose escalation period to match the dosing of the Artemisia product). We have chosen this as a comparator in consultation with SIBO and herbal medicine content experts as alfalfa matches the texture and color of Artemisia annua and, in the doses used, will provide no meaningful amounts of FODMAPs or antimicrobial phytochemicals. The alfalfa will be sourced from Bulk Apotherapy, LCC, and encapsulated at the same facility as the Artemisia capsules. Containers of placebo capsules will be kept in a secured cabinet before being administered, under climate-controlled conditions, and checked weekly to ensure consistent ambient temperature.
Complete blood count
RBC, WBC, platelets
Time frame: 5 weeks
Comprehensive metabolic profile
eGFR, electrolytes, BUN:Cr, AST, ALT, GGT, alkaline phosphatase, bilirubin
Time frame: 5 weeks
Vital sign measurement (heart rate)
bpm
Time frame: 5 weeks
Vital sign measurement (blood pressure)
mmHg
Time frame: 5 weeks
Vital sign measurement (temperature)
degrees F
Time frame: 5 weeks
Vital sign measurement (weight)
kg
Time frame: 5 weeks
Vital sign measurement (height)
meters
Time frame: 5 weeks
Vital sign measurement (body mass index)
weight (kg) / \[height (m)\]²
Time frame: 5 weeks
Adverse event monitoring
Adverse events
Time frame: 5 weeks
Quality of life
IBS-QoL
Time frame: 5 weeks
Symptom severity
GI symptom severity (IBS-SSS)
Time frame: 5 weeks
Adequate relief
IBS-AR
Time frame: 5 weeks
H2 gas response
H2 gas lactulose breath test. Day 0 to 35 difference measured by Δ baseline to 90 min in each test.
Time frame: 5 weeks
CH4 gas response
CH4 gas lactulose breath test. Day 0 to 35 difference measured by peak CH4 in each test.
Time frame: 5 weeks
Gas resolution
H2/CH4 lactulose breath test. Count of those with \<20 ppm rise from baseline to 90 min H2 and \<10 ppm absolute on CH4 by trial closeout.
Time frame: 5 weeks
Plan to share: No
No publications or documents are linked to this record.
Started Jan 2025 (actual). Primary completion is estimated for Jan 2026, 12 months after the start.
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