Moves a living microbial community from a screened donor into the gut. Evidence is strong only for a bowel infection that keeps returning after antibiotics. Two uses rest on small trials: inflamed bowel, repeat liver-related confusion. Blood-sugar gains fade within months. Rejuvenation findings are animal-only. Harms include bowel upset, bowel-disease flare-ups, rare deadly infection transmission. (Full Review)

Protocol

Standard protocol for recurrent infection

Single dose of screened donor material

Colonoscopy, enema or oral capsules, 24–48 hours off vancomycin

Single versus repeated dosing

One dose for recurrent infection

Inflammatory and metabolic indications used repeated dosing in every trial showing benefit

Best time of day

Morning delivery

Near-universal convention; no trial has compared timing directly

Time to effect

Recurrent infection

Days

Symptoms resolve in days; cure assessed at 8 weeks

Colitis remission

8 weeks

Assessed at the end of an eight-week course; rarely durable beyond a year without repeat dosing

Insulin sensitivity

6 weeks

Peaked at 6 weeks, faded by 18

Benefits

High: Resolution of recurrent Clostridioides difficile infection; induction of remission in active ulcerative colitis; reduced recurrence of hepatic encephalopathy in cirrhosis

Medium: Short-term improvement in insulin sensitivity; reduced body fat and systemic inflammation after a single course

Low: Restored response to immune checkpoint therapy in advanced melanoma; improvement in motor symptoms of Parkinson disease; symptom relief in irritable bowel syndrome; reduced carriage of multidrug-resistant bacteria

Speculative: Reversal of age-associated changes in the gut, brain and eye; extension of healthspan and lifespan

Contraindications

Severe neutropenia (neutrophil count below 500 cells/µL)

Active graft-versus-host disease

Within 90 days of allogeneic stem-cell transplantation

High-dose induction chemotherapy

Advanced untreated HIV (CD4 below 200 cells/µL)

Toxic megacolon, fulminant colitis, suspected perforation

Pregnancy and breastfeeding

Uncontrolled swallowing disorder, high aspiration risk (capsule, nasoenteric)

Key Interactions

Systemic antibiotics: Absolute timing conflict

Immunosuppressants and biologics (prednisone, infliximab, tacrolimus): Caution to contraindication by degree of suppression

Proton pump inhibitors and H2 blockers (omeprazole): Caution

Antimicrobial supplements (berberine, oregano oil, garlic): Caution

Antimotility and adsorbent over-the-counter agents (loperamide, bismuth, charcoal): Caution

Probiotics and Saccharomyces boulardii: Additive but potentially competitive

Fermentable fiber and prebiotic supplements (inulin, guar gum, psyllium): Additive rather than adverse

Anti-PD-1 checkpoint inhibitors (pembrolizumab, nivolumab): Deliberate combination

Bowel preparation and procedural sedation: Caution

Risk & Side Effects

High: Transient gastrointestinal symptoms

Medium: Transmission of pathogenic or drug-resistant organisms; serious adverse events related to delivery; disease flare in inflammatory bowel disease

Low: Transfer of donor metabolic phenotype; harm from the antibiotic pre-treatment used in many protocols

Speculative: Long-term transfer of unrecognized disease risk

Monitoring

Marker	Target	Why
Clostridioides difficile toxin / PCR stool test	Negative	Confirms cure or relapse
Fecal calprotectin	Below 50 µg/g	Detects mucosal inflammation and flare
High-sensitivity C-reactive protein	Below 0.5 mg/L	Tracks systemic low-grade inflammation
Fasting insulin	2–5 µIU/mL	Earliest metabolic signal, peaking near 6 weeks
HbA1c	4.8–5.3%	Whether insulin changes become lasting blood-sugar change
Albumin	4.2–5.0 g/dL	Nutritional and hepatic reserve; procedure tolerance
Absolute neutrophil count	2,000–5,000 cells/µL	Screens for neutropenia that makes transplant unsafe
ALT	Below 20 U/L men, 17 U/L women	Detects liver stress from antibiotic pre-treatment
Stool microbial diversity (Shannon index)	No target; change from own baseline	Confirms donor engraftment, not health per se

Cadence: Baseline before the procedure; contact at 1 week; stool retest at 8 weeks; inflammatory and metabolic markers at 8 weeks, 6 months, then every 6–12 months for a chronic indication.

Qualitative Assessment

Stool frequency, form and urgency, tracked daily for the first fortnight
Bloating, cramping and flatulence, and whether they settle within 72 hours
Energy and daytime alertness
Cognitive clarity and word-finding, particularly where the indication involves the gut–brain axis
Sleep continuity, as a practical marker of gastrointestinal settling
Appetite and early satiety, relevant where the intent is metabolic

Fecal Transplant for Health & Longevity

Protocol

Benefits

Risk & Side Effects

Monitoring

Qualitative Assessment