Is the black mould in my bathroom making us sick?

If you've noticed black mould creeping along the shower grout and you're worried about your family breathing it in, that worry is reasonable — you're not overreacting. Health authorities including the World Health Organization link damp and indoor mould to respiratory symptoms, especially in babies, older people, and anyone with asthma. The sensible response isn't panic; it's removing the mould and stopping it coming back.

Can bathroom mould actually affect our health?

Yes — indoor damp and mould are associated with respiratory problems, and the bathroom is the highest-risk room because it's warm, wet, and often poorly ventilated. The World Health Organization's guidelines on indoor air quality (Dampness and Mould, 2009) conclude that occupants of damp or mouldy buildings are at increased risk of respiratory symptoms, wheeze, and worsening asthma. Black mould in shower grout and silicone releases spores every time you disturb it — a hot shower, a running fan, a wiped-down wall. For a healthy adult that's usually a minor irritant. For a baby, an elderly parent, or an asthmatic, repeated exposure in an enclosed, steamy room is worth taking seriously. This isn't medical advice, and if anyone in your home has ongoing coughing, congestion, or breathing trouble, see a GP — but reducing the mould at the source is squarely within your control.

Why is the bathroom the worst room for this?

Mould needs moisture, warmth, and a surface to grip — a bathroom gives it all three, several times a day. Every shower loads the air with steam that condenses on grout lines, silicone seals, and the cold corner where the wall meets the ceiling. Grout and silicone are exactly the porous, textured surfaces spores love to settle into, and unlike a painted wall, they hold water long after the mirror clears. If your extraction fan is weak or the window stays shut, that moisture sits for hours. That's why the same black line comes back in the same seam no matter how often you wipe it. The room isn't dirty — it's damp, and damp is what mould eats.

Does bleaching it actually make it safe?

Not really — bleach removes the colour, not the colony. Chlorine bleach (sodium hypochlorite) lightens the black stain so the seam looks clean, but the mould's root structure often survives in the porous grout beneath, and the spores are still there. Two weeks later the black is back in the same spot, because it never truly left. On top of that, you've filled a small enclosed room with chlorine fumes — the exact opposite of what you want when you're worried about what your family is breathing. Clove oil works differently: its active compound, eugenol, is a documented natural antifungal that disrupts fungal cell membranes (Pinto et al., 2009, Journal of Medical Microbiology). It kills the mould at the root rather than just hiding its colour, so you break the cycle instead of repeating it — without the fumes.

What's the safest way to clean it with kids in the house?

Use a bleach-free spray you don't have to evacuate the room to apply, and ventilate while it works. The Clove & Eucalyptus Mould Spray is made from just five ingredients — water, castile soap, methylated spirits to dry the surface, 100% pure eucalyptus oil and 100% pure clove oil — with no chlorine and no caustic soda. You mist it lightly onto the grout and silicone, leave it for about 20 minutes to let the clove oil do its work, then rinse or wipe. No holding your breath, no sending the kids outside. One honest note: on old silicone the black staining can penetrate the material itself, so the mould can be dead and the seam may still look grey — the win here is that it stops coming back, not that badly stained silicone is restored to white.

We've been distilling eucalyptus oil in Australia since 1895 — five generations of the same family. When you've put your own name on a bottle for 130 years, you don't sell people industrial bleach and call it natural. A verified reviewer in Melbourne put it simply: "I have tried a lot of mould products in my life, but this has been one of the best. Very effective, easy to use. Follow the directions and to date the mould has not resurfaced."

Frequently asked questions

Is black bathroom mould dangerous to breathe?

Health authorities including the WHO link indoor damp and mould to respiratory symptoms, with higher risk for babies, older people and asthmatics. It's worth removing at the source. This isn't medical advice — if anyone has ongoing breathing symptoms, see a GP.

Will cleaning the mould fix our symptoms?

Removing the mould and the damp that feeds it reduces exposure, which is the part you can control. Any persistent health symptoms should be assessed by a doctor.

Is the Clove & Eucalyptus Mould Spray safe to use around children?

It's bleach-free with five disclosed ingredients and no chlorine fumes. Follow the label directions, and keep it out of reach of children like any cleaning product.

Does it get rid of the black stain completely?

It kills the mould at the root. On old silicone that's been stained through, the seam may still look grey even once the mould is dead — the real benefit is that it stops returning.

You know what to do now: clear the mould at its source, keep the room ventilated, and give it a light weekly spray so it doesn't creep back. For the full method, read how to get rid of black mould in shower grout and silicone for good, whether bleach is safe in a small enclosed bathroom, and why mould keeps coming back in shower silicone. Or go straight to the Clove & Eucalyptus Mould Spray.

References: World Health Organization, WHO Guidelines for Indoor Air Quality: Dampness and Mould (2009). Pinto, E. et al. (2009), Journal of Medical Microbiology, 58, 1454–1462.