Penicillium
Blue-Green Mold

What Does Penicillium Look Like?

Penicillium colonies typically appear blue-green, gray-green, or turquoise with a velvety or powdery texture. Some species have a white fringe at the edges. Under a microscope, Penicillium has a distinctive brush-like structure (penicillus) with chains of round conidia at the tips. It often grows on food items, wallpaper, carpet, and water-damaged insulation.

Where Does Penicillium Grow?

Penicillium is found nearly everywhere: soil, decaying plant material, food products, and indoor environments. Indoors it commonly grows on water-damaged walls, wallpaper, carpet padding, insulation, and refrigerator door seals. In South Florida homes it is frequently found in HVAC components and under sinks following plumbing leaks.

Health Risks of Penicillium Exposure

Penicillium exposure can trigger allergic reactions including sneezing, nasal congestion, watery eyes, and skin rashes. In people with asthma, elevated Penicillium levels can worsen symptoms. Some Penicillium species produce ochratoxin A, a mycotoxin with potential kidney and immune system effects. Penicillium and Aspergillus are often reported together in lab results and are sometimes listed as Penicillium/Aspergillus (Pen/Asp) because their spores are morphologically similar.

How to Prevent Penicillium in Your Home

Reduce indoor humidity with dehumidifiers. Fix plumbing leaks immediately. Inspect and replace water-damaged carpet, drywall, and insulation. Clean refrigerator seals and drip pans regularly. Have HVAC systems serviced and filters changed on schedule.

Frequently Asked Questions