Digital health · Patient communities
Crohnology
A patient-run symptom and treatment tracking network for Crohn's disease and ulcerative colitis, built by a patient who wanted research to start with the people living the condition. It grew to tens of thousands of members on almost no money, fed a peer reviewed research network, and then went quiet. The site has not loaded since 2021.
A diagnosis at twelve, a network by twenty eight
Sean Ahrens was diagnosed with Crohn's disease at age 12. Managing a flare meant calling his doctor and waiting a month for an appointment, then facing an inconclusive array of possible prescriptions. When he moved to the San Francisco Bay Area for college, he met, for the first time, a lot of other people who had Crohn's or colitis too, and the insights from years of their own treatment experiments struck him as something the rest of medicine was not capturing.
In 2011 he quit his job and began programming from home. The result was Crohnology.com, a site where patients logged symptoms and what they were trying, whether a drug, a diet, meditation, acupuncture or, in one documented case, a deliberate parasite infection, and saw what was working for people like them.
The gap it was aimed at
Crohn's disease and ulcerative colitis together make up inflammatory bowel disease, which Ahrens has said affects about one in 150 people, roughly 3 million in the United States. The causes are not fully understood and there is no cure. Traditional clinical trials are small and expensive; Ahrens wanted to put a tracking tool in every patient's pocket and let day to day data become the research.
"As a patient, it's extremely important to me to get the right information to treat my condition that's unbiased by economics," he told MIT Technology Review in 2013. "Unfortunately that's not the world we live in."
Two cofounders and an accelerator run
Ahrens built the first version alone, then brought in Will Cole, a college friend, as cofounder. Crohnology entered Rock Health's San Francisco cohort in 2011 and presented at Rock Health's 2012 Health Innovation Summit, then went through Y Combinator's Summer 2012 batch. Sarah Branon, another college friend and a web developer, later joined full time, and the team worked from the Mission district in San Francisco.
Growth was organic, spreading almost entirely through an in-app invite feature that let patients bring in friends with the same condition. By September 2013, Crohnology counted 4,210 patients in 66 countries. Ahrens later put the lifetime total at roughly 30,000 patients worldwide, all without a dollar spent on marketing.
Research, a magazine cover story, and money trouble
The platform became a source for actual research. Sean Ahrens is a coauthor, credited under the affiliation "Crohnology, San Francisco, CA," on a 2016 paper in the Journal of the American Medical Informatics Association describing the Crohn's and Colitis Foundation of America's PCORnet Patient Powered Research Network, built with the University of North Carolina at Chapel Hill. That same year, the American Journal of Gastroenterology published Ahrens's own first person account, under the same Crohnology affiliation, of treating his Crohn's with self-administered pig whipworm eggs; the journal ran it with a note calling the topic controversial and stressing that a single patient report should not change practice. In 2014, at the Health 2.0 conference, a Genentech product development leader described consulting Crohnology, alongside sites like PatientsLikeMe and MediGuard, to redesign a competitive inflammatory bowel disease clinical trial after patient surveys found that fear of embarrassment was keeping people from signing up.
None of that solved the money problem. "The challenge was that we were so underfunded," Ahrens said in a 2022 podcast interview. He put the early numbers at about $150,000 going into Y Combinator, then roughly another $200,000 after launch. Pitching venture investors on a business model built around selling patient data to pharmaceutical companies conflicted with the altruistic case he had made to the patients contributing that data. "I couldn't raise the funding and feel true to what I actually wanted to do," he said. "So I laid down the computer."
What happened to the site
PitchBook, a commercial data provider, lists Crohnology's status as "Out of Business" dated October 14, 2015. But the Internet Archive shows crohnology.com still returning normal pages years after that, with the last working snapshot dated September 17, 2021. A Reddit user asked what had happened to the site as early as October 2020. Archive.org's records then show server errors from late 2021, a redirect through 2022 and 2023, a not found page in 2024, and a server error again as of this report. Ahrens moved on to product roles at other health technology companies, including DrChrono, and by 2021 was living remotely from Puerto Rico.
What is proven, and what is still claimed
| Evidence | What the record shows | Source type |
|---|---|---|
| UNC and CCFA research tie | Ahrens is a named coauthor, affiliated with Crohnology, on a 2016 JAMIA paper describing the CCFA Partners Patient Powered Research Network built with UNC Chapel Hill. | Public record |
| Peer reviewed founder paper | American Journal of Gastroenterology published Ahrens's first person case report on self-treating Crohn's with pig whipworm eggs, credited to his Crohnology affiliation, in 2016, with a note calling it controversial and stressing a single patient report cannot change practice. | Public record |
| Genentech tie | A Genentech product development leader told the 2014 Health 2.0 conference that Crohnology and MediGuard patient surveys shaped an inflammatory bowel disease clinical trial's design, reported by MobiHealthNews. | Independent |
| Qu Biologics tie | Described in the company's own profile as a research collaborator. No independent report, paper or announcement describing that collaboration was found. | Not found |
| Patient count | 4,210 patients in 66 countries by September 2013, per independent reporting. Ahrens later recalled roughly 30,000 over the platform's life; the company's own profile cites over 27,000. | Independent, varies by year |
| Funding on record versus founder account | PitchBook records $20,000 tracked. Ahrens has said about $150,000 came in around Y Combinator and roughly $200,000 more after launch, near $350,000 total. | Differs from PitchBook |
| Shutdown date | PitchBook marks Crohnology "Out of Business" on October 14, 2015. Internet Archive snapshots show the site still working as late as September 2021, with errors and redirects only appearing after that. | Differs from PitchBook |
| SEC Form D | No Form D was found in SEC EDGAR under Healthy Labs or Crohnology. Small, early friends and family or accelerator rounds are not always filed under Regulation D. | Not found |
| FDA, clinical trial registry, NIH award to the company | None found. Crohnology was a consumer tracking and community platform, not a regulated device, drug or trial sponsor. | Not applicable |
Read plainly: Crohnology's research role is documented in peer reviewed literature, and an independent account puts its data in front of at least one major pharmaceutical company. What is not documented anywhere public is a funded, sustainable business.
What to watch
- Whether Crohnology's patient data or community was preserved or transferred anywhere; no announcement of an acquisition, shutdown notice or data transfer plan was found.
- Whether the CCFA Partners Patient Powered Research Network, later known as IBD Partners, which Ahrens also helped build, continued the research mission after Crohnology went offline.
- Whether Qu Biologics or Genentech ever published results from work that involved Crohnology's patient data.
In their words
“Unfortunately that’s not the world we live in.”
Sean Ahrens, founder, MIT Technology Review, 2013 · Independent
“Patients sharing data about how they feel, the type of treatments they’re using, and how well they’re working is a new behavior.”
Malay Gandhi, chief strategy officer, Rock Health, MIT Technology Review, 2013 · Independent
“I always thought that beer was bad for me, but the survey results gave me a lot of confidence that this was causing a problem.”
Ken Spriggs, Crohnology patient, MIT Technology Review, 2013 · Independent
“When it comes to designing a clinical trial, how do you actually put the patient first?”
Joling Mew, product development leader, Genentech, Health 2.0 conference, reported by MobiHealthNews, 2014 · Independent
“I’m a little bit sad about Crohnology because I built a thing that from a product standpoint, and just judging from the reactions and growth of the network, was a really well designed product that scratched an itch that was completely unaddressed by other products.”
Sean Ahrens, founder, On the Health Record podcast, 2022 · Interview
“The challenge was that we were so underfunded.”
Sean Ahrens, founder, On the Health Record podcast, 2022 · Interview
“Over the course of its existence, it grew to 30,000 patients with Crohn’s and colitis throughout the world, and that was all organic. We didn’t spend a dollar on marketing.”
Sean Ahrens, founder, On the Health Record podcast, 2022 · Interview
“We envision a world in which every patient can instantly tap into the knowledge and experiences of every other, so that every patient can learn how well treatments have worked for others.”
Crohnology about page, archived 2021 · Company-stated
Related companies
Sources
- Public recordHarnessing person-generated health data to accelerate patient-centered outcomes research: the Crohn's and Colitis Foundation of America PCORnet Patient Powered Research Network (CCFA Partners)
- Public recordOpening (and Swallowing) A Can of Worms to Treat My Crohn's Disease
- IndependentPatients Take Control of Their Health Care Online
- IndependentHealthcare social network connects Crohn's disease patients
- IndependentHow Genentech taps into online patient communities to improve clinical trials
- InterviewOn the Health Record: Conversation with Sean Ahrens
- IndependentCrohnology company profile
- IndependentCrohnology (YC S12) lets patients are collaborating for better health
- IndependentCrohnology company page
- IndependentCrohnology (by Healthy Labs) YC company profile
- IndependentSean Ahrens biography
- IndependentWhat Happened to Crohnology.com?
- Public recordcrohnology.com Wayback Machine capture history
- CompanyCrohnology (by Healthy Labs) company profile
- CompanyAbout Crohnology
Profile researched and written by Healthcare Discovery. Last updated September 29, 2026.
