Rifaximin for IBS without Constipation: TARGET 3
New England Journal of Medicine (2011)
Significantly improved IBS symptoms including bloating, abdominal pain, and stool consistency vs placebo over 2 weeks, with durable response.
How it works
Marek's Guided Optimization® Program combines advanced lab testing, a dedicated health coach and medical provider, and a personalized treatment plan, all built around your data.
Resources
The process
1
Start your assessment
Complete your 45-min intake assessment
2
Get your labs drawn
4,000 partnered lab locations nationwide
3
Review with your coach
Screen-by-screen lab review
4
Receive your protocol
Treatment delivered to your door
Why Marek
The only program pairing you with a dedicated health coach and medical provider, built on precision diagnostics, with no subscription required.
Resources
Meet our co-founder
Derek
Co-Founder · MPMD Podcast
"Over time, I found it incredibly difficult to get medical oversight for myself and my family that reflected the latest research, and that was preventative. That's why I started Marek Health."
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What we test
Every client's lab panel is hand-selected from 1,000+ available biomarkers, built around their specific goals.
Panel categories
Resources
Treatments
700+ medical provider-prescribed therapies built from your labs. Browse by category or explore the full formulary.
Rifaximin
Oral tablet (275mg)Not available in all statesMarketing purposes only. Actual medications, if prescribed, are dispensed by a licensed pharmacy.
gut
RifaximinRifaximin
Non-absorbable rifamycin antibiotic acting locally in the GI tract. FDA-approved for traveler's diarrhea, hepatic encephalopathy, and IBS-D. Key role in SIBO treatment protocols due to gut-limited activity with minimal systemic absorption.
Gut-limited action with minimal systemic absorption
Effective for SIBO eradication
Does not significantly disrupt colonic microbiome at standard doses
Low resistance development
No commitment · HSA/FSA eligibleNo commitment · HSA/FSA eligible
How it works
Mechanism of action
Inhibits bacterial RNA polymerase, with broad-spectrum activity against gram-positive and gram-negative aerobes and anaerobes. <0.4% systemic absorption ensures gut-localized action with minimal systemic side effects or resistance concerns.
The baseline panel.
Every Marek client receives this baseline panel before a provider review. Your provider may add additional biomarkers based on your health history, symptoms, and goals, pulling from 1,000+ available markers. See more biomarkers →
Hormone Profile
12 markers
Sex hormones
- Total TestosteroneLC/MS
- Free TestosteroneEquilibrium Dialysis
- Estradiol, Sensitive / UltrasensitiveLC/MS
- Sex Hormone Binding Globulin (SHBG)
- ProgesteroneLC/MSFemale panel
- Prolactin
- Luteinizing Hormone (LH)
- Follicle-Stimulating Hormone (FSH)
- hCG, Total, QuantitativeFemale panel, pre-menopause
Adrenals & neurosteroids
- Cortisol
- DHEA-S
Growth hormone / IGF-1
- Insulin-Like Growth Factor I (IGF-1)
Thyroid Status
3 markers
Thyroid hormones
- Thyroid Stimulating Hormone (TSH)
- Free T4
- Free T3
Heart Health
9 markers
Cardiovascular health
- Total Cholesterol
- HDL Cholesterol
- LDL Cholesterol
- LDL:HDL Ratio
- VLDL Cholesterol
- Triglycerides
- Apolipoprotein-B (ApoB)
- C-Reactive Protein, High Sensitivity (hsCRP)
- Lipoprotein(a) (Lp(a))
Metabolism
3 markers
Insulin sensitivity
- Blood Glucose
- Fasting Insulin
- HbA1c
Organ Function
26 markers
Liver & pancreas
- AST
- ALT
- Bilirubin, Total
- γ-Glutamyl Transferase (GGT)
Kidney function
- BUN
- Creatinine w/ eGFR
Comprehensive Metabolic Panel (CMP)
- Glucose
- Blood Urea Nitrogen (BUN)
- Creatinine
- eGFR
- BUN/Creatinine Ratio
- Sodium
- Potassium
- Chloride
- Carbon Dioxide, Total
- Calcium
- Protein, Total
- Albumin
- Globulin, Total
- Albumin/Globulin (A/G) Ratio
- Alkaline Phosphatase (ALP)
- AST
- ALT
Prostate health
- Prostate-Specific Antigen (PSA)Male panel
- Free PSAMale panel
- % Free PSAMale panel
Nutrient Status
31 markers
Vitamins & minerals
- Vitamin D, 25-OHD (25-Hydroxy)
- Magnesium, RBC
Iron status
- Iron
- Iron Saturation
- TIBC
- UIBC
- Ferritin
Complete Blood Count (CBC)
- White Blood Count (WBC)
- Red Blood Count (RBC)
- Hemoglobin (Hgb)
- Hematocrit (HCT)
- MCV
- MCH
- MCHC
- Red Cell Distribution Width (RDW)
- Platelets
- Neutrophils
- Neutrophils (Absolute)
- Lymphocytes
- Lymphocytes (Absolute)
- Neutrophil/Lymphocyte Ratio
- Monocytes
- Monocytes (Absolute)
- Eosinophils
- Eosinophils (Absolute)
- Basophils
- Basophils (Absolute)
- Immature Cells
- Immature Granulocytes
- Immature Granulocytes (Absolute)
- NRBC, w/ Reflex for Immature Cells
Clinical evidence
The research behind Rifaximin.
Safety profile
Monitoring & safety information.
Commonly reported side effects
- Nausea
- Flatulence
- Headache
- Abdominal pain
Less common but serious risks
- C. difficile infection (rare)
- Hypersensitivity reactions
Generally not appropriate for
- Hypersensitivity to rifaximin or rifamycin class
- Intestinal obstruction
Typical monitoring
- Symptom resolution
- SIBO breath test (post-treatment)
- Liver function (hepatic encephalopathy indication)
FAQ
Quick answers.
Non-absorbable rifamycin antibiotic acting locally in the GI tract. FDA-approved for traveler's diarrhea, hepatic encephalopathy, and IBS-D. Key role in SIBO treatment protocols due to gut-limited activity with minimal systemic absorption.
Gut-limited action with minimal systemic absorption. Effective for SIBO eradication. Does not significantly disrupt colonic microbiome at standard doses. Low resistance development.
Common side effects include: nausea, flatulence, headache, abdominal pain. Most side effects are dose-dependent and may resolve with continued use or dose adjustment.
Non-absorbable rifamycin antibiotic acting locally in the GI tract. FDA-approved for traveler's diarrhea, hepatic encephalopathy, and IBS-D. Key role in SIBO treatment protocols due to gut-limited activity with minimal systemic absorption.
Treatments are dependent on licensed clinical prescription. Client costs vary based on individual labs and panel in treatments and services.