Human Microbes
FDA issued a warning letter to Human Microbes (Riverside, CA, United States) on Feb 9, 2024, citing 21 CFR 1271.3. Subject: CGMP, Deviations, Biologics License Application (BLA).
From the letter: “Your products are not the subject of an approved BLA or an approved application under 21 U.S.C. § 355.”
At a glance
What a reviewer notes before reading: findings, citations, the response deadline and what the letter warns of.
- Violations
- 4 findings · 3 issue types
- Cited
- 21 CFR 1271.3
- Response due
- 15 working days after receipt of this letter
- FDA asks for
- 4 actions
- Named as possible actions
- Seizure, injunction
- Issued by
- Center for Biologics Evaluation and Research
- Published status
- No close-out recorded
AI assisted findings
Model-assisted reading of each issue. Open one to see the FDA text it comes from, and check it against the full letter.
01Registration, listing & premarketProducts are marketed as drugs and biological products without approved applications or INDs.
Your products are not the subject of an approved BLA or an approved application under 21 U.S.C. § 355. In addition, there is no IND in effect for their use. Therefore, your products are both unapproved new drugs and unlicensed biological products.
02Labeling, claims & marketingProducts are offered for treatment of conditions beyond C. difficile, outside the enforcement discretion policy.
Based on a review of your website, you offer FMT for treatment of diseases and conditions other than C. difficile infection. As noted in FDA’s November 2022 guidance, data related to the use and study of FMT to treat diseases or conditions other than C. difficile infection not responding to standard therapies are more limited, and study of FMT for other uses is not included in the aforementioned enforcement policy.
03Labeling, claims & marketingProducts are offered directly to patients for self-administration without licensed health care provider oversight.
Although your website recommends that patients “discuss their plans with their doctor,” it offers your products directly to patients, including for self-administration. For example, your website indicates that donors can ship your products directly to patients and provides instructions on methods of self-administration. Therefore, there is no assurance that a licensed health care provider treating each of these patients is directing the screening and testing of the stool donor and stool for the patient, as described in the November 2022 guidance.
04Components & suppliersProducts raise potential significant safety concerns due to inadequate donor screening.
Your products also raise potential significant safety concerns due to inadequate donor screening. We also note the reported safety concerns described in the “donor results spreadsheet” on your website (e.g., “increased intestinal pain, nausea, sweating, and loss of appetite among other things”).
What FDA requested
- Notify FDA in writing of specific steps taken to correct violations
- Explain each step to prevent recurrence and provide related documentation
- If unable to complete corrections in 15 days, state reason and completion date
- Comprehensively review website and other labeling and marketing materials
FDA Warning Letter
23 paragraphs · 2 sectionsText as published on FDA.gov, retrieved Sep 8, 2026. Layout added for reading; the wording is FDA’s. View on FDA.gov (opens in a new tab)
1WARNING LETTER
0 paragraphs
2Warning Letter #CBER-24-672740
17 paragraphs
Date: February 09, 202 Dear Mr. Harrop:
This is to advise you that the United States Food and Drug Administration (FDA) has reviewed your website at www.humanmicrobes.org in February 2024, which contains instructions on how to buy fecal microbiota for transplantation (FMT) (hereinafter, “your products”). Your website indicates that you are offering for sale (in the United States, Canada, and other parts of the world) FMT in various forms (e.g., capsules, enemas, and infusions) for the treatment or prevention of various diseases or conditions. For example, your website states the following:
“FMT is a lifesaving treatment for the deadly gut infection Clostridium Difficile (C. Diff) and has shown promising results in clinical trials for many other conditions [1], such as IBS (irritable bowel syndrome), IBD (inflammatory bowel disease), Parkinson’s disease, fibromyalgia, chronic fatigue syndrome (CFS), multiple sclerosis, autism, diabetes, and mental health disorders like depression, anxiety, and bipolar.”
“FMT may also have potential applications in the treatment of obesity, autoimmunity, cardiovascular disease, cancer, and more.”
“FMT is also a treatment option to attenuate adverse effects associated with antibiotic use.”
Additionally, your YouTube channel (https://www.youtube.com/watch?v=jPRg-_voHXQ) has a video titled, “We want your poop” that contains the following statements:
“FMTs offer a potential new treatment option for a long list of conditions…including irritable bowel syndrome, obesity and even mental disorders.”
Refers to a patient “cured her bipolar disorder after receiving an FMT”
Because these statements indicate that your products are intended for use in the mitigation, treatment, or prevention of disease, they are drugs under section 201(g)(1)(B) of the Federal Food, Drug, and Cosmetic Act (FD&C Act) [21 U.S.C. § 321(g)(1)(B)]. Your products are also “new drugs” under section 201(p) of the FD&C Act [21 U.S.C. § 321(p)] because they are not generally recognized as safe and effective (GRASE) for their labeled uses. Additionally, your products are biological products as defined in section 351(i) of the Public Health Service Act (PHS Act) [42 U.S.C. § 262(i)] because they are applicable to the prevention, treatment, or cure of a disease or condition of human beings.1
Please be advised that to lawfully market a drug that is also a biological product, a valid biologics license application (BLA) must be in effect [42 U.S.C. § 262(a)]. Such licenses are issued only after a demonstration that the product is safe, pure, and potent. A biological product for which a BLA has been approved under 42 U.S.C. § 262(a) is not required to have an approved application under section 505 of the FD&C Act [21 U.S.C. § 355; 42 U.S.C. § 262(j)]. Otherwise, with certain exceptions not applicable here, a new drug may not be introduced or delivered for introduction into interstate commerce without an approved application from FDA in effect, as described in 21 U.S.C. § 355(a). While in the development stage, such products may be distributed for clinical use in humans only if the sponsor has an investigational new drug application (IND) in effect as specified by FDA regulations [21 U.S.C. § 355(i); 42 U.S.C. § 262(a)(3); 21 CFR Part 312]. Your products are not the subject of an approved BLA or an approved application under 21 U.S.C. § 355. In addition, there is no IND in effect for their use. Therefore, your products are both unapproved new drugs and unlicensed biological products. Furthermore, based on the statements on your website, you cause the introduction or delivery for introduction into interstate commerce of your products in violation of the FD&C Act [21 U.S.C. § 331(d)].
We note that your website references an “FDA enforcement discretion policy” regarding FMT. In November 2022, FDA issued a revised guidance titled, “Enforcement Policy Regarding Investigational New Drugs Requirements for Use of Fecal Microbiota for Transplantation to Treat Clostridioides difficile Infection Not Responsive to Standard Therapies”. This guidance document indicates that FDA intends to exercise enforcement discretion regarding the IND requirements for the use of FMT in treating Clostridioides difficile (C. difficile) infection not responding to standard therapies, where, among other things, the stool donor and stool are qualified by screening and testing performed under the direction of the licensed health care provider for the purpose of providing the FMT product to treat his or her patient and use of the FMT product does not raise reported safety concerns or potential significant safety concerns.
Based on a review of your website, you offer FMT for treatment of diseases and conditions other than C. difficile infection. As noted in FDA’s November 2022 guidance, data related to the use and study of FMT to treat diseases or conditions other than C. difficile infection not responding to standard therapies are more limited, and study of FMT for other uses is not included in the aforementioned enforcement policy. In addition, although your website recommends that patients “discuss their plans with their doctor,” it offers your products directly to patients, including for self-administration. For example, your website indicates that donors can ship your products directly to patients and provides instructions on methods of self-administration. Therefore, there is no assurance that a licensed health care provider treating each of these patients is directing the screening and testing of the stool donor and stool for the patient, as described in the November 2022 guidance. Your products also raise potential significant safety concerns due to inadequate donor screening. We also note the reported safety concerns described in the “donor results spreadsheet” on your website (e.g., “increased intestinal pain, nausea, sweating, and loss of appetite among other things”). For these reasons, your products would not fall within the enforcement discretion policy referenced above.
The violations cited in this letter are not meant to be an all-inclusive list of violations that may exist in connection with your products. You are responsible for promptly investigating and determining the causes of any violations, correcting them, and preventing their recurrence, and ensuring full compliance with the law.
We advise you to comprehensively review your website and other labeling and marketing materials to ensure that you are lawfully marketing your products in full compliance with the FD&C Act, the PHS Act, and their implementing regulations. Failure to adequately address this matter may result in enforcement action without further notice, including, without limitation, seizure and/or injunction.
This letter notifies you of our findings and provides you an opportunity to address the above deficiencies. If you believe that your products are not in violation of the FD&C Act and the PHS Act, include your reasoning and any supporting information for our consideration in your response to this letter.
Within fifteen working days of receipt of this letter, please notify FDA in writing of the specific steps that you have taken to correct any violations. Your response should include an explanation of each step being taken to prevent the recurrence of violations as well as related documentation. If you cannot complete all corrective actions within fifteen working days, state the reason for the delay and the date by which you will complete the correction.
Your written response should be sent to the following address: U.S. Food and Drug Administration, Center for Biologics Evaluation and Research, Document Control Center, 10903 New Hampshire Avenue, WO71-G112, Silver Spring, MD 20993-0002. Please also email your response to CBERDCMRecommendations@fda.hhs.gov.
Citations and trends
Each 21 CFR section, ISO 13485 clause and issue type in this letter, how often it appears across all letters, and its trend by the year FDA issued the letters. 2026 runs to Nov 3, 2026, compared with the same dates last year. Select a row or a bar to see those letters in Letters. As cited in this historical letter, not a statement of current requirements.
Regulations
Also cited: 21 CFR 312
Issue types
Record details
- Issuing center
- Center for Biologics Evaluation and Research
- Issuing office
- Center for Biologics Evaluation and Research
- Location
- Riverside, CA, United States
- Letter posted date
- Mar 12, 2024
- Letter issue date
- Feb 9, 2024
- Addressed to
- Founder
- Inspection dates
- Not recorded
- Response window
- 15 working days after receipt of this letter
Read the source clause
Within fifteen working days of receipt of this letter, please notify FDA in writing of the specific steps that you have taken to correct any violations.
- Record length
- 1,250 words · 0 recorded redactions
- Published status
- No published close-out
- FDA reference
- CBER-24-672740
- Original letter
- View on FDA.gov (opens in a new tab)
- Dataset last checked
- Nov 11, 2026 · How this is built
A response window is not a calculated due date. Source excerpts are selected passages. Finding interpretations and categories are model-assisted. Verify the original letter before relying on a finding.