Can Mold in Your Home Make You Sick? Facts About Mold Exposure
Jun, 26 2025
It starts with a smell—a bit earthy, sort of musty, unmistakable if you've ever visited an old basement. Before you spot it, you breathe it in: mold. It’s easy to brush off as a harmless part of nature, something that just happens in damp places. But here’s the kicker: some kinds of mold, when they move indoors, can actually make people sick. From sniffles and itchy eyes to far more serious health issues, the reality is, mold lurking in your building isn’t just gross—it might be quietly messing with your health.
What Is Mold and Why Does It Thrive Indoors?
Mold is just a type of fungus—a cluster of tiny organisms that break down dead stuff. Out in the wild, that’s helpful. Indoors, though, they’re a real pain if they find a comfy spot. Mold loves moisture more than kids love lollies. It grows where things are damp, poorly ventilated, or never quite dry. Old houses in Wellington, for instance, know all about it. It’s not just “gross gunk on the wall.” Mold sends out little invisible spores that float through the air. If you’ve got mold in one room, those spores might travel stubbornly around your whole flat, hitching a ride on air currents, pets, or even your coat. The World Health Organization rattled off a stat that about 10–50% of all buildings worldwide get some kind of dampness problem serious enough for mold to set up shop. Not just old villas, either. Even swanky new builds can get mold if there’s a water leak or if a bathroom doesn’t vent properly.
You might see the obvious signs—blackish splotches on the ceiling, weird fuzzy patches near the windows, even green specks in the wardrobe. The thing is, the really harmful molds might not be visible. They can hide behind walls, above ceilings, and under carpets. Stachybotrys (nickname: black mold) is a notorious type, but mold comes in loads of varieties—some not even colored black. They all reproduce by tossing spores into the air, which is how they get into your lungs, eyes, and even onto your dinner plate if you’re unlucky.
What does mold need to thrive inside? Three things: moisture (from leaks, high humidity, or condensation), organic material (wood, cardboard, wallpaper, dust), and time. Leave a leak unchecked for as little as two days, and mold can start to colonize. It’s not about being dirty—sometimes you just didn’t notice a little drip under the sink. In Wellington, the mix of rainy winters and older, less-insulated houses is just perfect for mold. That old “it’s just a bit of mold, mate, nothing to worry about” attitude can land you with surprising problems if you ignore it too long.
How Does Mold Make You Sick?
The biggest question people have is, does mold exposure actually make you sick? Science says yes, and it’s not just a horror movie scenario. Mold causes health issues mostly in three ways.
First, there’s the allergic reaction. Even if you’re not the allergic type, mold spores can still annoy your airways, giving you classic hay fever kinds of symptoms—sneezing, runny nose, watery eyes, coughing. Some folks get worse chest tightness or wheezing, especially if they’ve got asthma or sensitive lungs. Kids are at a higher risk—stats from the Centers for Disease Control and Prevention note that children living in moldy environments have higher rates of asthma, and hospital visits for breathing problems are higher in damp houses.
Then there’s the irritant effect. Mold doesn’t just sit quietly—when it grows, it produces compounds called microbial volatile organic compounds (MVOCs) that can irritate your eyes, nose, and throat just by being in the air. These aren’t just harmless scents either; some can cause headaches and brain fog. Ever walked into a stuffy room and suddenly felt dizzy or icky, only to notice a black patch above the door? That’s no coincidence.
Some molds make toxins called mycotoxins. These are more rare in buildings but not unheard of. Breathing in a high dose over a long time can seriously mess with your immune system, cause rashes, and even start neurological issues. Black mold (Stachybotrys chartarum) is infamous for this, but not every black-looking mold is the toxic culprit. It’s tricky, since you usually can’t tell by sight alone what type you’ve got.
Most healthy adults get mild symptoms or even none, but people with asthma, allergies, compromised immune systems, babies, elderly folks, and those recovering from surgeries or illnesses are especially vulnerable. Fatigue, headaches, unexplained lingering coughs, sinus trouble that never clears—if you feel better outside but worse at home or work, mold could be behind it.
| Symptom | How often it appears (mold sickness) |
|---|---|
| Sneezing | Very common |
| Coughing / throat irritation | Very common |
| Runny or blocked nose | Common |
| Watery eyes | Common |
| Headaches & fatigue | Moderately common |
| Wheezing or trouble breathing | Common in asthma or allergy sufferers |
| Unexplained rashes | Uncommon, but possible |
| Brain fog, memory issues | Rare, seen with longer-term toxicity |
The tricky thing is how non-specific these symptoms are. Mold sickness feels like bad hay fever, a cold that never goes away, or just that “blah” feeling that improves when you leave the building. Sometimes, even pets get affected—wheezing cats and snuffly dogs are not as rare as you’d think in damp homes. If two or three people sharing a space are all feeling off but can’t pinpoint why, asking, “Could it be mold?” isn’t just hypochondria; it’s smart detective work.
Identifying Mold Problems in Your Space
Spotting mold isn’t always a matter of looking for dark stains on the bathroom ceiling. Sometimes, the only hint is that musty smell—the one that feels a bit like wet soil or dirty socks. That smell comes from the chemical compounds mold releases as it grows, and it’s often the first clue something’s up behind the scenes.
If you can see mold, start checking nearby areas for hidden patches. Mold tends to thrive out of sight—in wall cavities, under carpets, behind the fridge, or in cramped cupboards. Water stains, bubbling paint, or blistering plaster are signs of leaks and a warning flag for potential mold. Renters often miss these because landlords paint over moldy patches without fixing the root cause, which just delays the problem. If you rent, it’s your right to ask for proper repairs, not just a quick touch-up paint job.
Beyond visible spots, watch for condensation, especially on windows in winter. Persistent condensation signals high humidity—perfect conditions for mold. Kitchens, bathrooms, laundry rooms, and basements are danger zones, with steamy air and often poor airflow. If you ever pull a piece of furniture away from a wall and spot fuzzy green, grey, or black growth, don’t dismiss it as “just dust.”
There are home mold test kits sold online, but be careful—they don’t always give reliable info. Sometimes, it’s easier and more trustworthy to call in a professional, especially if you see a lot of mold or have persistent health issues. Professionals can sample air and surfaces and figure out the exact type and amount of mold, which is helpful if you’re battling a mystery cause of your symptoms. But whether or not you spot visible growth, that musty smell alone is reason enough to act.
Protecting Yourself and Preventing Mold Sickness
Now for the most practical bit—how do you stop mold from taking hold in the first place? It comes down to controlling moisture and boosting air flow. Fix leaks right away, even the little drips under sinks or windows. The biggest mistake is waiting for a “proper time” to call someone when in reality, every extra day gives mold a chance to multiply. Use extractor fans when you’re cooking or showering, and make sure the vent leads outdoors, not back into your roof space. In places like Wellington, where rainy seasons and chilly weather team up, running a dehumidifier can be a game changer.
Don’t push furniture flat up against cold, external walls—it traps moisture and creates a hidden breeding ground. Leave a finger’s width of space for airflow. Wipe condensation off your windows before it drips onto sills and carpets. If humidity is an ongoing battle, look into investing in reusable moisture absorbers or small silica gel packs for wardrobes and cupboards.
Keep surfaces and rooms as dry as possible. Don’t ignore weird water spots or a mushy smell—these are promises of future headaches if you leave them alone. If you find a patch of mold smaller than a pizza, you can usually clean it yourself. Wear gloves, a mask, and use a mix of soap and water, or a store-bought mold spray. Never dry brush or vacuum moldy areas, since that just blasts spores everywhere. For bigger problems or if the mold keeps coming back, it’s smart to get professionals involved. They’ll deal with removal and look for the root moisture cause.
- Keep all rooms well-ventilated, especially after baths or cooking
- Fix leaky roofs, gutters, plumbing ASAP
- Use dehumidifiers or moisture absorbers in damp-prone rooms
- Keep an eye on hidden nooks—under carpets, behind furniture
- Don’t ignore musty smells—they’re almost always worth checking out
Bottom line: You really can get sick from mold in a building, whether that building is your home, school, or office. It slips in silently but can leave you tired, sniffly, or even truly unwell. Don’t wait for green fuzz to cover every wall or for your cold to outlast the winter. If you spot, smell, or even suspect mold, act fast—your lungs, your brain, and everyone sharing your space will thank you. And if your landlord says you’re overreacting? Show them the evidence. Mold isn’t just ugly, it’s a genuine health risk worth sorting out—before you need more than a box of tissues to cope.