Penicillium Mold (Penicillium)

Types of Mold › Penicillium

Penicillium is a familiar blue-green mold — the same genus behind penicillin, but indoors it's an unwanted colonizer known for spreading quickly. It's a frequent find after water damage and in chronically damp spaces.

Where it grows

It thrives on water-damaged materials, wallpaper, carpet, fabrics, and insulation, and can take hold fast once something stays wet. Homes that have had a leak or flooding often develop Penicillium within days.

Is it dangerous?

It commonly triggers allergic responses — sneezing, congestion, and respiratory irritation — particularly in sensitive individuals. Because it spreads rapidly, prompt removal limits how far it travels.

How it's removed

Because it moves quickly, fast containment matters. Pros isolate the area, remove affected porous materials, treat surfaces, and dry out and repair the moisture source. Speed is the theme — see what to do after water damage.

Think you've found Penicillium in your home? A free assessment confirms what it is and whether it needs professional removal. See also our cost guide and signs of mold.