BackMold Illness in Houston, TX: What You Need to Know
Hurricane Harvey dropped up to 52 inches of rain over five days. Of the 204,000 homes affected, 75% were uninsured. No insurance meant no professional remediation. Just a quick dry-out, a fresh coat of paint, and a house back on the market.
That was nine years ago. Most of those homes are still occupied. And almost none were re-verified with a HERTSMI-2 (Health Effects Roster of Type-Specific Formers of Mycotoxins and Inflammagens, 2nd version) dust test, one of the most objective tools for evaluating whether an environment is safe for mold-susceptible people. The city moved on. The mold didn't.
"I struggled for years with chronic symptoms that other doctors wanted to give me band-aid solutions for, but with MoldCo, I actually got to the root cause." — MoldCo patient, via Trustpilot
If you've been in a Houston home dealing with fatigue, brain fog, or chronic sinus issues that won't resolve, your environment deserves a closer look. The MoldCo Home Test ($199) ships a HERTSMI-2 kit to your door with accredited lab analysis and expert interpretation. The Starter Panel ($56) checks three biomarkers tied to mold illness at any of Houston's 18 LabCorp locations. Learn more about mold exposure symptoms.
The two failures that made Houston ground zero
The first failure was environmental. Hurricane Harvey's flooding hit an estimated 135,000 single-family homes. According to the EPA's Mold Cleanup guidance, mold begins growing on surfaces within 24 to 48 hours of water intrusion. The window for effective drying is hours, not days. Under pressure and tight timelines, thousands of homes were dried out and declared fine without species-level testing.
The second failure is medical. Very few practitioners in Texas are trained in the Shoemaker Protocol for mold-related illness, and for a metro of Houston's size, demand far exceeds supply. Your regular doctor doesn't run the biomarkers that reveal mold toxicity (MSH, TGF-beta1, MMP-9). Standard blood work comes back "normal" while the markers that actually matter go untested.
This is the pattern that keeps patients stuck. A gastroenterologist runs an endoscopy and finds nothing. A pulmonologist checks lung function and it's fine. An allergist tests for IgE mold allergy and it's negative. Each specialist looks through a single-organ lens and misses the multi-system picture of mold illness.
If you're not sure whether mold allergy or mold illness better describes your situation, that distinction matters. Learn more about mold toxicity treatment and the Shoemaker Protocol.
Not sure if your symptoms line up? Take the free signs quiz.
"Exposed to high levels of toxic mold for months in a rental home. Brain fog, fatigue, sick more often, working memory clobbered. Treatment with MoldCo has been a huge blessing, finally recovering." — MoldCo patient, via X
A city that never dries out
Houston averages 75% relative humidity year-round, nearly double the CDC's recommended indoor threshold of 30-50%. According to NOAA's Gulf Coast climatological records, relative humidity in the Houston metro area exceeds mold-growth thresholds on roughly 80% of days annually. Houston doesn't get a true off season for mold.
The numbers tell the story: 75% average humidity (the CDC recommends 30-50% indoors), 51.84 inches of annual rainfall, and a high-risk season stretching from June through October. Houston's humid subtropical climate (Cfa classification) means mold-favorable conditions persist most of the year.
After Harvey, invasive mold infections across four Houston hospitals rose approximately 47%, with a 17.5% increase in mold-positive cultures. Researchers documented that post-Harvey patients faced heightened mold exposure through floodwater contact and disturbed spores during cleanup, particularly affecting immunocompromised residents. As CBS News reported, mold is causing a hidden health crisis nationally as extreme weather events increase. Houston sits at the center of that pattern.
For about 24% of the population, a genetic variant (HLA-DR) makes it harder for the body to clear biotoxins on its own. If you carry that gene and live in a city with 75% humidity, your environment is working against you. The result is often a pattern of inflammatory symptoms (fatigue, cognitive effects, immune dysregulation) that don't resolve with standard treatment and may warrant further investigation.
We spend approximately 90% of our time indoors, where indoor air quality can be 2-5x worse than outdoor air. In Houston, that number isn't abstract. It's the air in your home right now.
Where the risk concentrates
Not every part of Houston carries the same risk. Six neighborhoods have distinct mold vulnerability profiles worth knowing.
Meyerland. Flooded four times since 2015: Memorial Day 2015, Tax Day 2016, Harvey 2017, and again in 2019. Each cycle damages homes that were just rebuilt, creating layers of water intrusion that standard remediation may not address.
Greenspoint. A renter-heavy area with older housing stock. Texas doesn't require landlords to disclose past mold in rental properties, though landlords must fix conditions that materially affect tenant health or safety.
Kingwood. This San Jacinto River community experienced a 500-year flood event during Harvey. Post-flood remediation happened quickly, but homes that dried out without a follow-up HERTSMI-2 test may still harbor water-damage mold species behind walls.
Clear Lake / NASA area. Low along Galveston Bay, persistent humidity and periodic coastal flooding. Even well-maintained homes develop hidden mold in HVAC systems running year-round.
Houston Heights / Woodland Heights. Historic pier-and-beam foundations trap moisture in crawl spaces. Aging plumbing creates ongoing small-leak risks. Unlike slab-on-grade homes, pier-and-beam construction has an entire layer beneath where mold can grow unseen.
Katy / Barker Cypress. During Harvey, the Army Corps released water from the Addicks and Barker reservoirs into neighborhoods previously considered safe from flooding. Many of those homes were remediated under pressure and tight timelines.
When the risk peaks
Houston's mold risk isn't seasonal the way most cities think about it.
June through October is highest risk. Hurricane season brings heavy rainfall, peak humidity, and flooding. Water intrusion is most likely and remediation timelines are most compressed.
April through May and November stay elevated. Spring storms and late-season rain catch homeowners off guard. The transition between heating and cooling seasons creates condensation inside walls and ductwork.
December through February is lower, but not zero. Houston homes run HVAC year-round. Condensation is a common hidden moisture source even in cooler months.
Testing: get data before you guess
If you suspect mold, getting data is the first step out of ambiguity.
Why DIY kits fall short. Hardware store mold test kits detect spores everywhere (because mold spores are everywhere) but can't identify species, measure concentrations, or assess health risk. Their short recommended collection periods also frequently miss mold that longer professional sampling would catch.
HERTSMI-2 dust testing. This analyzes DNA from five water-damage-associated mold species. Scores below 11 indicate the environment is likely safe for people susceptible to mold illness. For a deeper look at what these scores mean, see our ERMI/HERTSMI-2 interpretation guide.
Your options in Houston. A professional mold inspection typically costs $300-$600. The MoldCo Home Test ($199) is a ship-to-home HERTSMI-2 kit with accredited lab analysis and expert interpretation included. For blood work, Houston has 18 LabCorp locations where you can complete a Starter Panel ($56) to check three key biomarkers (TGF-beta1, MMP-9, MSH) associated with mold-related illness. For comprehensive testing guidance, see our mold illness testing guide.
"I was amazed when I received my results because they came with a clear guide that explained what everything meant and what steps I needed to take next." — MoldCo patient, via Trustpilot
Ready to get data on your home? Order MoldCo Home Test - $199.
If you remediate, verify
For mold-susceptible people, dead mold is just as harmful as living mold. Mycotoxins persist whether the colony is alive or not. The IICRC S520 standard calls for physical removal of contaminated materials, not chemical kill methods. For the roughly 24% of people with genetic susceptibility, thorough particle removal is especially critical.
Post-remediation verification with HERTSMI-2 (target: below 11) is the most objective way to confirm the environment is likely safe for re-occupancy. Some patients also test subjectively by spending time in the remediated space to see if symptoms return. Wait approximately 4 weeks after remediation and thorough small-particle cleaning before re-testing. This matters especially for post-Harvey homes that may have been dried out but never properly re-verified.
In Texas, all persons performing mold assessments and remediation must be licensed by the Texas Department of Licensing and Regulation (TDLR). A MAC license requires 40 hours of approved training and a state examination. You can verify any contractor at the TDLR verification portal. Houston remediation typically costs $1,700-$7,500 depending on scope. For detailed standards, see our mold inspection and detection guide.
Why telehealth makes sense here
Houston's 671-square-mile sprawl and specialist shortage make telehealth not just convenient but practical. MoldCo is a clinician-led telehealth platform built for mold-related illness, guided by the Shoemaker Protocol. Founded with Dr. Ritchie Shoemaker and Dr. Scott McMahon, it's backed by 30+ years of mold illness research and outcomes data from over 30,000 patients.
For Houston residents, that means biomarker testing at any of 18 local LabCorp locations, telehealth consultations with trained practitioners, ship-to-home HERTSMI-2 kits, and prescriptions shipped to your door. Texas is a full-service state with both lab testing and telehealth care available.
Pricing. The Starter Panel is $56. An initial consultation is $129 with a 100% refund if it's not a fit. Ongoing membership is $79/month. Most patients pay $150-$300/month all-in. Treatment can begin while you're still in the exposure environment.
Check your eligibility. 18 LabCorp locations. $129 initial consultation with 100% refund if not a fit.
Order Starter Panel - $56. Available at any of Houston's 18 LabCorp locations.
Is MoldCo available in Houston?
Yes. Texas is a full-service state. Houston residents have access to all MoldCo lab panels ($56-$799) at 18 LabCorp locations, plus MoldCo Care telehealth ($129 initial, $79/month ongoing). Prescriptions and home test kits ship directly to your door. Check your eligibility.
How much does mold testing cost in Houston?
A professional in-home inspection typically runs $300-$600. MoldCo's ship-to-home HERTSMI-2 kit is $199 with accredited lab analysis and expert interpretation. The Starter Panel is $56 at any of Houston's 18 LabCorp locations.
What are the highest mold risk areas in Houston?
Six neighborhoods stand out: Meyerland (four flood cycles since 2015), Greenspoint (renter-heavy with older housing stock), Kingwood (Harvey 500-year flood), Clear Lake/NASA (bay-adjacent humidity), Houston Heights/Woodland Heights (pier-and-beam crawl spaces), and Katy/Barker Cypress (Addicks/Barker reservoir release during Harvey).
Does Texas require mold licensing?
Yes. Texas requires all persons performing mold assessments and remediation to be licensed through TDLR. You can verify any Houston contractor at the TDLR verification portal. Texas also has seller disclosure requirements under Texas Property Code Section 5.008, though landlord mold disclosure isn't explicitly required for rental properties.
How quickly does mold grow after Houston flooding?
In Houston's humidity, mold can begin growing within 24 to 48 hours after water intrusion. If water sat for more than 48 hours and the area wasn't dried below 60% humidity within that window, there's a reasonable chance mold has already started growing on the affected materials.
Any health-related claims made on this site have not been evaluated by the Food and Drug Administration (FDA). The information provided on this site is not intended as a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. MoldCo assumes no responsibility or liability for any errors or omissions in the content of the references, nor for any actions taken in reliance thereon.