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There's no special purple mold to fear, but any mold growing indoors needs a moisture fix

Purple Mold: What Purple Spots Usually Mean and What To Do

Purple mold isn't a recognized type, and black mold isn't purple. What purple or dark stains may be, why color doesn't show risk, and what to do next.

7 min read

"Purple mold" isn't a recognized type of mold. We found no government, university, or medical source that treats it as a category. Molds come in many colors, and a few can look purple. The USDA Forest Products Laboratory notes that mold spores are usually black, green, or brown but can also be gray, purple, or red. Some purple-looking stains aren't mold at all, such as iron stains on wood. The earlier version of this article described Stachybotrys, the so-called black mold, as a purple mold. The CDC describes it as greenish-black. Either way, color doesn't tell you how dangerous a mold is. The CDC says all molds should be treated the same with respect to potential health risks and removal: fix the moisture and remove the growth.

What Purple Discoloration Might Be

Mold. In its guide to mold and mildew on wood, the USDA Forest Products Laboratory says mold often appears as black, green, or brown fuzzy or powdery patches, "though spores can also be gray, purple, or red in color." Some common molds vary widely in color. The University of Adelaide's mycology reference says *Fusarium* colonies range from whitish to yellow, pink, red, or purple. Quebec's public health institute, INSPQ, notes that finding *Fusarium* in a home is a sign of humidity.

Stain fungi on wood. The Forest Products Laboratory's *Wood Handbook* says sap and blue stains on wood usually range from bluish to black, gray, or brown, "although various shades of yellow, orange, purple, and red are sometimes encountered." It adds that mold and stain fungi affect the strength of wood only slightly.

Iron stain on wood. Not every dark stain is biological. The Forest Products Laboratory describes iron stain as "an unsightly blue–black or gray discoloration" caused by iron reacting with natural compounds in wood. Oak, redwood, cypress, and cedar are especially prone, and it often appears near metal fasteners or after rain or dew. The same guide offers a simple check: oxalic acid removes iron stain, and if bleach removes the discoloration instead, it was probably mildew.

Chemical stains. The Wood Handbook also notes that some non-microbial stains in wood resemble stains caused by fungi.

Gray mold on fruit. On grapes and berries, the common gray mold Botrytis produces fuzzy, gray-brown spores, according to UC IPM, and infected berries may turn brown or reddish. On dark fruit, it can look purplish.

Is Purple Mold Dangerous?

A purple color doesn't make mold more or less dangerous. NIOSH says the color of mold "does not necessarily indicate that it is more or less dangerous." It also notes that certain molds can produce toxins, but "the molds themselves are not toxic or poisonous."

What's established is that indoor mold can affect some people. The CDC says mold may cause a stuffy nose, sore throat, coughing or wheezing, burning eyes, or skin rash. People with asthma or mold allergies may have severe reactions, and people with weakened immune systems or chronic lung disease may get lung infections from mold.

The earlier version of this article said mycotoxins from purple molds cause headaches, memory loss, and neurological damage. That isn't supported:

  • The CDC says no test exists that proves a link between Stachybotrys chartarum and particular health symptoms.
  • The Institute of Medicine's review, summarized in the Surgeon General's 2009 call to action, found the evidence insufficient to determine whether mold or damp indoor environments are linked to neuropsychiatric symptoms.

For a fuller look at the evidence, see what kind of mold is dangerous in a house.

Do You Need To Test Purple Mold?

Usually not. The earlier version of this article suggested test kits and lab analysis to identify the exact type of mold. Health agencies say that isn't necessary:

  • The CDC does not recommend mold testing and says you don't need to know the type of mold, because any mold present needs to be removed.
  • The EPA says that when mold is visible, sampling is unnecessary in most cases, and that no standards have been set for airborne mold.
  • The Minnesota Department of Health says knowing the specific types of mold doesn't change what should be done to clean it up or fix the moisture problem.

An inspection can still help find hidden moisture or judge the extent of damage. See who to call for a mold inspection.

What To Do About Purple Spots on Walls, Wood, or Fabric

1. Rule out a stain. If the spots are on exterior wood near nails or metal, iron stain is possible. If the discoloration is fuzzy, powdery, spreading, or comes with a musty smell or moisture, treat it as mold.

2. Find and fix the moisture. The EPA says that if you clean up mold but don't fix the water problem, the mold will most likely come back. Look for leaks, condensation, poor ventilation, and damp storage areas.

3. Size it up. The EPA says most people can handle a moldy area smaller than about 10 square feet themselves.

4. Protect yourself. The CDC recommends at least an N95 respirator, gloves, and goggles, and fresh air when using cleaning products. People with asthma, allergies, lung disease, or weakened immune systems shouldn't do the cleanup.

5. Clean or remove.

  • Hard surfaces: scrub with detergent and water and dry completely. If you use bleach, the CDC says use no more than 1 cup in 1 gallon of water, and never mix it with ammonia or any other cleanser.
  • Wood: the Wood Handbook says surface mold on softwoods often can be brushed or surfaced off. The Forest Products Laboratory adds that mold causes no structural damage to wood by itself, but persistent leaks can encourage decay fungi that do.
  • Porous materials: the EPA says ceiling tiles, carpet, and similar materials may have to be thrown away if they become moldy.
  • Fabrics, leather, and books: see mold vs. mildew for extension-service cleaning methods by material.

6. Don't paint over it. The EPA says paint applied over moldy surfaces is likely to peel.

Call a professional for areas larger than about 10 square feet, mold inside walls or HVAC systems, contamination from sewage or floodwater, or growth that keeps returning.

Keep Mold From Coming Back

  • Keep indoor humidity below 60 percent, ideally between 30 and 50 percent, as the EPA recommends. See what humidity level helps prevent mold.
  • Dry wet materials within 24 to 48 hours after a leak or spill.
  • Run exhaust fans in bathrooms and kitchens.
  • Fix leaks and condensation promptly.
  • Store fabrics, papers, and leather in dry, ventilated spaces.

Frequently Asked Questions

Is purple mold the same as black mold?

No. "Black mold" usually refers to Stachybotrys chartarum, which the CDC describes as greenish-black. The EPA notes that "black mold" isn't a species or specific kind of mold. Neither color tells you how dangerous a mold is.

Can mold really be purple?

Occasionally. The Forest Products Laboratory says mold spores can be purple, and some molds such as Fusarium can form purple colonies. It's much more common for mold to be black, green, brown, or white.

What are purple or blue-black stains on my wooden deck?

On oak, cedar, redwood, or cypress, especially near nails or other metal, it may be iron stain rather than mold. The Forest Products Laboratory says oxalic acid removes iron stain, while bleach removes mildew.

Should I throw out fruit with purple or gray mold?

Yes for soft fruit such as grapes and berries. A USDA fact sheet, *Molds on Food*, advises discarding moldy soft fruits and vegetables because mold can spread below the surface.

What if I find purple mold at work or school?

Report it in writing to a supervisor, building manager, or school administrator, and see a doctor if you have symptoms. Our guide to mold in the workplace covers next steps and your options.

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