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.