Inside the Black Market Where People Make Thousands of Dollars Selling Their Poop

In late 2023, Alexandra, a 66-year-old retired woman in D.C., was defrosting a piece of human feces that she purchased over the internet. Her goal was to reduce the stool into a sloshy, biologically rich mixture, which could then be easily transferred past her rectum and into her colon. HumanMicrobes, the mysterious and legally questionable website that Alexandra purchased the poop from, recommended a turkey baster for the job. Alexandra opted for an enema bottle. “I gave myself a plain water enema first,” she told me. “Just to clear everything out.”

Then she tried it with the poop. For a while, she laid there allowing her homebrew liquid-fecal elixir to seep into her innards, where she hoped it would bloom new life into her troubled guts.

Alexandra suffers from cystitis, candidiasis, and irritable bowel syndrome. She gets frequent urinary tract infections and has terrible acid reflux, and her palms occasionally become swollen. She cannot eat sugar without exacerbating these symptoms, and she struggles with carbs, too. Her conventional doctors never zeroed in on a cause. “They can write me off very easily as just being stressed and overreacting to everything,” she said. “It’s a description of a highly anxious old woman.”

After exhausting all of her options in the traditional American medical apparatus, Alexandra decided to take matters into her own hands. She abandoned her conventional doctors and looked for answers elsewhere. She started seeing two experts in functional medicine, a form of holistic, alternative, and occasionally less scientific treatment. When she described her symptoms to them, they gave their blessing to seek out a “fecal microbiota transplant,” or FMT. In other words, they wanted her to implant someone else’s poop in the hope that it would quell whatever was ravaging her body.

FMTs have been around for a while. The first recorded instance of a fecal-based remedy occurred in ancient China, and today, they’re one method used to treat Clostridioides difficile (C. diff), a bacterial infection that causes fever, nausea, and diarrhea, which can occur after antibiotics have inadvertently scoured a patient’s bowels of healthy microbes. Sahil Khanna, a gastroenterologist at the Mayo Clinic, uses a gardening metaphor to describe the process.

“If you want to kill dandelions growing in your backyard with a weedicide, the roots are going to remain behind, and you’re going to kill a lot of grass as well. You’ll wake up a week later and see double the dandelions,” Khanna told me. The dandelions, in his analogy, are the C. diff bacteria, while the weedicide is an antibiotic. “To fix the problem, you need to kill the dandelions, and then steal good grass from your neighbor’s backyard and plant it there.” The good grass from your neighbor—that’s the poop. This approach, fighting C. diff with healthy stool, is currently the only governmentally certified use of FMT. Last year, the Food and Drug Administration approved Vowst, the first orally administered FMT treatment for C. diff. It contains live bacteria manufactured from, you guessed it, human feces. (Naturally, patients are instructed to take a laxative before downing their doses.)

Scientists think that transplanted poop might be useful for patients suffering from other chronic gut illnesses, too. Some early research suggests FMT could be a treatment for Crohn’s. Or, perhaps, irritable bowel syndrome: A review of trials totaling just under 500 patients found that it seemed to relieve some symptoms of irritable bowel syndrome, though the results were not statistically significant, and the authors concluded that other interventions were instead worth further research.

“We are still looking at things at a very high level,” said Majdi Osman, chief medical officer of OpenBiome, a nonprofit research firm that studies and distributes stool for investigational FMTs. He is a believer in the therapeutic potential of superior bacteria, but maintains that scientists are “quite a ways away” from saying FMT is effective for ailments other than C. diff. “We just don’t have the data yet,” he said.

This presented a problem for Alexandra. She didn’t have C. diff—it had been ruled out early in her diagnostic journey. She also didn’t have time to wait for more data—she was sick, and she wanted to get better. Maybe, just maybe, all of her gastrointestinal anguish could be solved with a stool transfer.

Without a diagnosis of C. diff, there was no way for Alexandra to access FMT through aboveboard channels. Her doctors informed her that the treatment couldn’t be prescribed off-label, either. Her only remaining option was to go underground. That’s when she found HumanMicrobes, the black market for poop.

Michael Harrop, the sole owner and operator of HumanMicrobes, likes to describe his practice as something akin to the Dallas Buyers Club of human waste. Harrop does not have a background in medicine, nor did he offer me a detailed personal biography when I reached him over the phone. (When asked for his age, Harrop said, “I try not to keep track of it. I’m in my late 30s.”) But he did tell me that he, like Alexandra, became interested in FMT after enduring an onslaught of poor health.

Harrop said he developed a variety of debilitating chronic illnesses in childhood—chronic fatigue, troubled breathing, IBS, “low brain function”—that greatly curdled his quality of life, and that those conditions worsened after taking an antibiotic, which he believes disrupted the ecosystem in his gut. Harrop said that these frailties eventually forced him to drop out of high school, and before his foray into FMT brokerage, he spent most of his adult life as a “disabled guy” playing video games—Counter-Strike and StarCraft II, specifically. It was during those sedentary days that he discovered the majesty of the gut biome, through the scattered selection of forums that made up the nascent online FMT community. After reading everything he could about the treatment, Harrop believed he finally had the chance to get his health in order.

“It’s the only near-complete treatment that restores the microbiome,” he told me. “It’s the endgame.”

Harrop started HumanMicrobes in 2020 in order to match fecal “super-donors” with buyers willing to spend a premium price to ingest it. Harrop refers to the website as a business and his primary commercial enterprise. The poop he sells costs around $1,000 per “dose,” and is distributed in either capsule form (for the “upper route”) or split into pieces packed in dry ice (for the “lower route”). The resulting revenue is split evenly between Harrop and whoever the stool previously belonged to. Unlike the FMT treatments you might receive at the Mayo Clinic, there is not a specialist prepping the poop for you. Harrop never handles the feces directly. This is an ad hoc, online-only operation, delivered peer-to-peer, with Harrop functioning as something like an international middleman for poop. (Yes, they ship worldwide.)

The HumanMicrobes website, which is studded with stock images of white-coated doctors peering into microscopes, claims that fewer than 0.1 percent of the human population possesses the “healthy, unperturbed, disease-resistant microbiomes” necessary to produce quality, medicinal stool. (This is a standard echoed by some of the more aboveboard FMT distributors—Osman joked that qualifying for OpenBiome’s stool donorship program is more difficult than getting into Harvard.) Harrop ascertains these qualities by issuing a lengthy, self-made questionnaire to the prospective donors who apply on the website—auditing, among other things, their body fat percentage, their food cravings, “risky sexual behavior,” and whether they were birthed via cesarean section or vaginally. Furthermore, if a donor scores high enough on Harrop’s private scoring system, he and the HumanMicrobes community will divide the cost for them to receive a fecal test from a doctor to screen for “a handful of known pathogens.” (Future testing, says Harrop, is “up to the recipients.”) Afterward, the donor will be added to HumanMicrobes’ in-house database, so people like Alexandra can inspect their wares.

“The ultimate stool donor is probably something like a 2–18 year old Michael Jordan,” reads Humanmicrobiome.info, another website owned by Harrop, which broadcasts a working theory that children tend to produce superior FMT material due to the fact that they’re “less likely to have taken antibiotics.”

Humanmicrobiome.info also provides a verbose set of instructions of how donors can safely “harvest” and store their poop in a basic residential freezer. Some of its procedures bring to mind The Anarchist Cookbook. For instance, in order to efficiently seal stool into over-the-counter gelatin capsules, the site recommends first creating a fecal slurry, and inserting it into a plastic bag with one corner snipped off. Then, the donor is to “squeeze” the foul batter into the unsealed pills, “similar to how you apply frosting.”

Once a donor has fully assembled their inventory of preserved stool, and is ready for it to be shipped on demand, they’ll be added to HumanMicrobes’ Google spreadsheet, which essentially operates like a Yelp for the bootleg FMT community. All of Harrop’s fecal dealers are listed, alongside a brief description of their biological metrics, personal hobbies, and—of course—the structural consistencies of their poop, before it was smooshed into a capsule. (“Female. Born 1998. Tennessee. Crossfit. Nursing student. Brown, floating, variable in size.”) Previous buyers leave comments elaborating on their experience with the reaping of the vendor’s bowels—both positive and negative—so their peers may make informed choices about the poop they wish to ingest. (“Bad gas. Probably from undigested protein in the donor’s stool,” reads one. “Lowered libido,” reads a second. “An increase in sociability and motivation,” offers a third.) Some donors are more popular than others. One, a Floridian born in 1997 with a background in track and field, has racked up 72 reviews—and if Harrop’s math is to be trusted, somewhere around $36,000 dollars for her troubles.

That figure pales in comparison to the owner’s. Adding up all the receipts listed on Harrop’s spreadsheet, he seems to have raked in about $80,000 since at least 2021 (though it’s unlikely the spreadsheet provides a full accounting of Harrop’s finances). This can make the price onerous on buyers. Alexandra herself spent $1,407 at HumanMicrobes, according to documents reviewed by Slate.

Naturally, doctors firmly reject Harrop’s operation. “Not a good idea. Terrible, terrible idea,” said Khanna. “We don’t understand if it’ll work, or if there will be adverse effects. And it’s against FDA regulations.” Osman, meanwhile, compares the pitfalls of a poorly screened, improperly stored FMT to something akin to a faulty blood transfusion. A DIY stool transfer increases your risk of infection and disease, he said. But, just as importantly, experts simply don’t know the long-term ramifications or side effects of the treatment. “It’s very important that patients are counseled on both the known risks and the unknown risks,” explained Osman. In research settings, “there are efforts underway to follow patients for 10 years.”

Osman has reason to issue that warning—FMT can be risky, even when it’s aboveboard. In 2019, two people died and six more became ill after receiving stool supplied by OpenBiome during clinical FMT trials. (The FDA said in 2020 it was “not known” if the infection contributed to those deaths, and an OpenBiome spokesperson said in an email to Slate that they were “deemed related to the patients other underlying medical conditions.”) In a different case, FMT supplied by a hospital-based stool bank was related to the death of an immunocompromised 73-year-old man, and according to a report published by the New England Journal of Medicine, the stool used in the trial was improperly screened for E. coli.* A week after the patient ingested a round of FMT capsules, he developed an infection resulting in “fever, chills, and altered mental status.” He was admitted to the ICU, where he succumbed to sepsis two days later.

“The development of defined, cultured, therapeutic microbial mixtures is an obvious and important future goal,” concluded the NEJM report. “Ongoing assessment of the risks and benefits of FMT research is needed, as are continuing efforts to improve donor screening to limit transmission of microorganisms that could lead to adverse infectious events.”

Harrop, for his part, concedes that he’s in uncharted territory. “It’s all very experimental still,” Harrop says. “I try to stress that.” On HumanMicrobes’ FAQ page, a passage reads, “It’s generally not possible to predict which stool donor will be best for any person or condition. Even people with similar conditions often get varying results from the same stool donor.”

In fact, Harrop still hasn’t gotten the results he’s looking for, and he still suffers from the ailments he described. “I haven’t been able to find a donor that has been really helpful for me,” he said. “Every donor is super unique. Their effects can change.”

At first, Alexandra didn’t get results. The FMT treatment she purchased from HumanMicrobes—the stool sample she was defrosting into a soup—failed to solve her gastrointestinal issues. Sure, she noticed “less flatulence,” but that was about it. Alexandra was disappointed but undeterred, so she returned to the site and purchased a set of capsules, theorizing that perhaps her body would respond better to the oral path than the rectal one. She decided to take one pill, five days in a row, and the results were even worse. “There was a lot of churning in my stomach. I felt like I was coming down with the flu,” she said.

But then, something miraculous happened. Alexandra reduced her dose to one capsule a week, and she got better. Her cystitis improved, allowing her to expand her diet for the first time in years. She started eating starchy foods—the same banquet that previously sidelined her—with no issues. The waves of stomach-gnawing nausea that plagued her in the beginning of the experiment subsided until they practically disappeared. “My reading on this was that my body was distressed about taking all these new microbes, but it got to the point where the microbes were established,” said Alexandra. “But it’s a black box.”

Alexandra said the money she spent at HumanMicrobes was worth every penny. She’s not alone. Shane Creamer, a 55-year-old IT director in Phoenix, is even more effusive about his endorsement of off-the-books FMT. Creamer purchased a black-market fecal transfer for his son who has autism from a clinic in Mexico, and claims that the treatment reversed many of his symptoms. “He became more verbal. He probably gained like 20 to 30 IQ points. His allergens went way down. Everything you can imagine got better for him,” said Creamer. “I looked around and found HumanMicrobes, I became a patient, and I’ve made huge progress in some of my personal areas as well.”

It is, admittedly, hard to take either Creamer or Alexandra at their word. In experiments involving one person, it’s just difficult to know what actually caused a change, and why. But both of them are convinced that their FMTs greatly improved their quality of life, and they would recommend the treatment to others if they could.

It seems unlikely that either of them are going to be able to purchase poop from HumanMicrobes for much longer, though. Shortly after I first emailed Harrop for this story, he informed me that he recently received a threatening letter from the FDA. The bureau was investigating his website’s noncompliance with a piece of administrative red tape called the “Biologics License Application,” which is necessary for any business marketing a “drug that is also a biologic product.” (The full complaint can be read on the FDA’s website.)

The government raised a number of concerns to Harrop, including the fact that he’s selling an FMT service that intends to address ailments other than C. diff, and most pertinently, that 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.” Harrop told me that he’s scheduled to meet with the bureau in a few months. After that, he’s not sure what will happen. (When reached for comment, the FDA told me that they don’t comment on “possible or ongoing investigations.”)

“From what I understand, I have to change the whole website to say we’re not selling stool with the purpose of FMT. That would be pretty drastic. We’d have to remove all mentions of it,” said Harrop. “I think it’ll be really complicated and expensive to get the license. It’s not something I can do on my own. I don’t even know if the way we were operating would qualify.”

In terms of selling poop online in 2024, Harrop probably doesn’t have much of a leg to stand on. But it does make you wonder if, say, 50 years from now when more research has been done, ardent FMT proselytizers like Harrop will be somewhat vindicated. Creamer’s claim that the treatment helped his son’s autism might sound like quackery, but it turns out there have been some early studies tying the improvement of autism symptoms to a fecal transfer; same with the mitigation of anxiety and depression. What if there is a miracle drug waiting for us in the right toilet?

“We have to tread carefully, with humility, when we try to understand and manipulate the microbiome to attempt to cure these intractable diseases. But I would say that we have a wide-open field, at the moment, for us to collectively understand new ways of treatment,” said Osman. “The microbiome might play a role in those conditions. It’s important for us to take a step back and do the science, repeating it and validating it, to make sure we aren’t giving false hope to patients who are often really desperate.”

Osman is touching on one of the fundamental paradoxes of FMT. Even the brightest experts in the field possess little clarity about what is truly happening in our abdomens. It’s a question that belies even the most fundamental ambiguities about the treatment. When I asked Dina Kao, one of the co-authors of the American Gastroenterological Association’s guidelines on FMT, how, stated plainly and simply, a fecal transfusion roots out a C. diff infestation, she responded, “We don’t really know for sure.” Kao has her hypotheses and prevailing hunches, but asserts nothing concrete. C. diff, as you recall, is the one condition a patient can get a legal FMT treatment to address outside of research settings. We know it’s effective, and that’s about it. That mysteriousness can help drive desperate patients to a currently unproven treatment for their unexplained symptoms. But it also means it’s a thrilling medical frontier.

Osman, for his part, hopes to see a world where the FMT standards are universally regulated, allowing for the treatment to become much more decentralized—akin to the way you and I might take advantage of a blood bank. “This reminds me that we are living through such an amazing time for the microbiome field, where things are moving so quickly,” he continued. He hopes that in the future we will have more “targeted, personalized ways to manipulate the gut microbiome.”

For now, all we can say for sure is that Alexandra is feeling better. Chalk it up to a placebo, a fluke, a scientific breakthrough, or an act of God, but she believes her FMT worked. Maybe, for now, that’s the best we can hope for.