Tiny Health grew from baby gut tests to clinicians and adults, raising a $33M Series B

an Austin startup selling at-home gut microbiome tests directly and through clinicians and health companies

Tiny Health bet people will pay out of pocket for at-home gut microbiome tests, and clinicians will use them if the company supplies the tests and training.

$50,000 of the founder's own money for an initial study, a $4.5M seed in 2021 and an $8.5M Series A in late 2023

Sew Hoy, whose earlier coupon startup Reclip.It was sold to Walmart Labs in 2013, incorporated Tiny Health a week after her son was born in 2020. Before raising a seed round she put $50,000 into an initial study and spent about a year collecting stool samples and building the platform. The company spent two years developing before launching the baby test in 2022.

Customers swab a stool sample and get a report on detected microbes with suggested next steps. Tiny Health uses shotgun metagenomic sequencing and sells a Tiny Plus subscription. It also offered pregnancy, vaginal microbiome and adult tests and says adults are now its larger segment. Customers took results to doctors, some asked for help interpreting them, and the company now serves 6,000+ practitioners, with a B2B arm called Powered by Tiny whose partners include Superpower, Fullscript and Mayo Clinic's executive health programs.

On 29 September 2026 Crunchbase News reported a $33M Series B led by B Capital, bringing total funding to $46M. Sew Hoy says revenue has more than doubled each year and Powered by Tiny grew fourfold last year; the company has about 40 employees and plans to hire 30 more. Insurance does not cover the tests, which Sew Hoy calls wellness rather than diagnostic.

Parents of children with conditions like eczema wanted more information, while clinicians had few practical tools for microbiome research.

Customers took direct-to-consumer reports to their doctors, which led clinicians to ask for help interpreting them.

The company argues shotgun metagenomic sequencing gives a broader view than tests for a limited set of microbes.

Long-term it wants to use its data to spot health risks before a condition develops.

A narrow entry product can reveal a bigger segment: here adults and clinicians outgrew the infant test. The tests cannot show what caused symptoms and are not covered by insurance.

As of 29 September 2026 Tiny Health had $46M raised, about 40 employees, 6,000+ practitioners and nearly 200,000 samples, and planned to expand with clinicians and fund research.