About the Black Mold Exposure Test (IgG)

Purpose of the test

This test checks whether your immune system has responded to black mold exposure. It doesn’t diagnose an allergy or detect mold in your environment. It measures your body’s IgG antibody response.

The mold species most commonly called “black mold” is Stachybotrys chartarum. It tends to grow on water-damaged drywall, cellulose-rich building materials, and surfaces with chronic moisture. A separate species, Aspergillus niger, is sometimes called black mold too. The specific panel ordered tells you which species is targeted.

Consider testing when unexplained chronic symptoms such as respiratory problems, fatigue, or neurological issues seem tied to a specific building. Construction workers, HVAC technicians, remediation workers, and real estate inspectors face higher exposure risk.

“Black mold poisoning” isn’t a formal medical diagnosis. According to the CDC’s facts on Stachybotrys chartarum, no test currently exists that proves an association between S. chartarum and particular health symptoms, and S. chartarum and other molds may cause health symptoms that are nonspecific. This test measures immune response to exposure. The CDC does not recommend blood or antibody testing to diagnose mold-related illness; finding and removing the moisture and mold source is the recommended response. This test can show whether your immune system has encountered the mold, but it cannot prove mold caused any symptoms. It doesn’t measure mycotoxin levels, diagnose mold allergy (IgE-mediated), identify mold species in your environment, or confirm active illness. For broader fungal tests, a different approach is used.

What does the Black Mold Exposure Test measure?

This test covers one marker from a single blood sample at a CLIA-certified lab, using an IgG immunoassay method.

Aspergillus niger IgG Antibody: Detects IgG antibodies your blood produces in response to Aspergillus niger (black mold) exposure.

Here’s how IgG differs from IgE. IgG antibodies are your immune system’s longer-term memory response. They can stay high for months to years after the exposure source is removed. A positive IgG result doesn’t mean you’re currently being exposed. It means your immune system responded at some point.

IgE antibodies are different. They represent an immediate allergic reaction and are measured by a separate test. As the MedlinePlus allergy blood test overview explains, IgE-based panels target immediate hypersensitivity responses and may not include every mold species. Most standard mold allergy panels may not include Stachybotrys chartarum, making the IgG exposure test the right tool when black mold exposure is the concern. Confirm panel contents with the ordering lab.

When should I get a Black Mold Exposure Test?

Consider testing if any of these apply:

Chronic cough, wheezing, or shortness of breath tied to a specific building
Persistent fatigue, headaches, or neurological symptoms at home or work
Sinus issues or skin irritation that improve when you leave a specific location
Visible mold growth or a history of water damage in your home or workplace
A professional environmental assessment showing Stachybotrys chartarum presence
Occupational exposure risk (construction, remediation, HVAC, real estate inspection)
A provider’s recommendation after unexplained illness

The “symptoms improve when you leave the building” pattern is worth raising with your provider, though it is not proof of illness. The NIH National Institute of Environmental Health Sciences notes that mold exposure can cause a range of respiratory and other symptoms, and that reducing exposure is the key step in managing health effects. If your respiratory or fatigue symptoms consistently ease when you’re away from a building, that is a useful clue. Keep in mind this test measures immune response, not whether mold is causing your symptoms, so it is one input your provider weighs alongside your history and a building assessment.

How It Works

How to get tested

Lab tests for mold exposure are ordered through a healthcare provider, clinic, or hospital lab. Testing.com connects users with CLIA-certified laboratory partners including LabCorp and Quest Diagnostics, where most U.S. tests of this type are processed.

Your provider orders the test, you visit a nearby patient service center or lab for a blood draw, and results come back through your provider’s patient portal or office. No at-home option is available for this test.

Before the test

No fasting is required. You don’t need to avoid food or drink beforehand.

No antihistamine hold is needed either. Unlike IgE allergy tests, IgG antibody levels aren’t influenced by antihistamines. Don’t stop taking any medicines unless your provider tells you to.

One exception: medications that suppress the immune system, such as corticosteroids or chemotherapy agents, can reduce IgG antibody production. If you take immunosuppressants, tell your provider before testing so results can be read in the right context.

Stay hydrated and wear a short-sleeved shirt or loose sleeves for easy vein access. That’s all the prep you need.

During the test

Bring a photo ID and any paperwork from your provider. Check in at the patient service center.
A phlebotomist draws blood from a vein in your arm. You’ll feel a brief pinch or pressure.
A small bandage covers the site afterward. Keep it on for at least 15 minutes.

The draw takes a few minutes. Most visits run about 15 to 30 minutes total.

You may notice light bruising or mild soreness over the next day or two. That’s normal. Call your provider if you notice lasting pain, significant swelling, or signs of infection at the site.

After the test

Results are typically ready within one to three business days after the lab receives your sample, though timing can vary by lab. You’ll get results through your ordering provider’s patient portal or office, not directly from the lab.

Don’t try to interpret results on your own. Talk with your provider first.

What Do My Results Mean?

If your results are negative

No IgG antibodies to black mold were detected above the lab’s threshold. That’s reassuring, but it doesn’t tell the whole story.

IgG antibodies take time to develop. If you tested shortly after a brief or recent event, your immune system may not have produced detectable levels yet. Retesting after a few weeks is reasonable if symptoms persist or you know an exposure occurred.

A negative blood test doesn’t confirm your home or workplace is mold-free. You’d need a separate environmental assessment for that.

If your results are positive

IgG antibodies to black mold were detected. Your immune system may have responded to Aspergillus niger (or Stachybotrys chartarum, depending on the panel). This may reflect past or ongoing exposure.

Here’s the key nuance: IgG antibodies can stay high for months to years after the exposure source is removed. A positive result doesn’t mean you’re currently being exposed. If you’ve already remediated the mold source, your result may reflect past exposure.

A positive result doesn’t confirm illness, toxicity, or “mold poisoning.” It shows your immune system responded. Your provider reviews results alongside your symptoms and health history to figure out what comes next.

Two follow-up steps are worth considering. First, talk with your provider about what the result means given your exposure timeline. Second, arrange a professional environmental assessment of your home or workplace. The blood test confirms your body was exposed. It doesn’t locate the mold source. Finding and removing the source is the key step in reducing ongoing risk. The EPA’s brief guide to mold and moisture is a useful starting point for understanding remediation options.

FAQs

Is this the same as a home mold test kit?

No. Home mold test kits (air samples, surface swabs, petri dish kits) test your environment for mold. This blood test checks whether your immune system has responded to black mold exposure. One tells you if mold is in your home; the other tells you if your body’s been exposed.

What's the difference between the IgG black mold test and the IgE black mold allergy test?

The IgG test detects a longer-term immune response to exposure. The IgE test detects an immediate allergic reaction. Most standard mold allergy panels may not include Stachybotrys chartarum, making the IgG test the right choice when black mold exposure is the concern.

Can this test diagnose black mold poisoning?

No. “Black mold poisoning” isn’t a formal medical diagnosis. This test measures whether your immune system produced IgG antibodies in response to black mold. It doesn’t measure mycotoxin levels, confirm active illness, or prove mold caused your symptoms.

How long do IgG antibodies stay elevated after black mold exposure ends?

They can stay high for months to years after the exposure source is removed. A positive result doesn’t necessarily mean you’re currently being exposed. If you’ve already remediated the mold source, a positive result may reflect past exposure. Talk with your provider about reading results in context.

If my blood test is positive, do I still need an environmental mold inspection?

Yes. A positive blood test confirms your immune system responded, but it doesn’t locate the mold source. A separate professional environmental assessment is needed to find and remediate the mold. Removing the source is the key step in reducing ongoing risk.

Can immunosuppressant medications affect my results?

Yes. Medications that suppress the immune system, such as corticosteroids or chemotherapy agents, can reduce IgG antibody production. You could get a lower-than-expected result even if exposure occurred. Tell your provider about all current medications before testing.