Feeling constantly tired, struggling with brain fog or dealing with unexplained headaches can be frustrating. When symptoms persist despite normal medical test results, many people start looking for answers elsewhere.

Online sources often suggest that mold, environmental chemicals and other hidden exposures may be behind a wide range of unexplained symptoms. Some direct-to-consumer tests claim they can identify these exposures and explain how they may be affecting your health.

So what does the science say, and when is environmental toxin testing actually helpful?

“People often ask about these tests when they’re dealing with persistent symptoms that haven’t been explained by standard medical testing,” says Anna B. Shannahan, MD, a family medicine and integrative medicine physician at Northwestern Medicine. “Many of these tests are sold directly to consumers online without much medical guidance. The results can sometimes lead to expensive or unnecessary treatments.”

Could Hidden Environmental Factors Affect Health?

In some situations, environmental exposures can affect health.

Examples include:

• Air pollution
• Mold and indoor dampness
• Cleaning products
• Makeup and personal care products
• Volatile organic compounds (VOCs) released from paints, furniture and building materials
• Certain heavy metals, such as lead
• Endocrine-disrupting chemicals, such as phthalates and bisphenol A (BPA), which may be found in certain plastics and consumer products
• Per- and polyfluoroalkyl substances (PFAS), sometimes called “forever chemicals,” which may be found in drinking water and food packaging

Scientists continue to study the long-term health effects of environmental exposures like PFAS, including how they affect the immune system and nervous system. Research suggests some may be associated with an increased risk of certain cancers.

Many environmental exposures have known health effects, especially at high levels or after years of exposure. Some are associated with:

• Respiratory disease
• Irritation
• Allergies
• Increased risk of other chronic diseases

What Symptoms Raise Concerns About Environmental Exposures?

Symptoms that commonly prompt questions about environmental exposures include:

• Fatigue
• Brain fog
• Difficulty concentrating
• Headaches
• Joint pain
• Muscle aches
• Bloating or gas
• Mood changes
• Respiratory symptoms

“These symptoms should be thoroughly evaluated by a doctor,” says Dr. Shannahan.

While these symptoms can raise concerns about environmental exposures, they are common and can have many causes, including:

• Sleep disorders
• Anxiety
• Depression
• Autoimmune conditions
• Thyroid disorders
• Medication side effects
• Nutritional deficiencies

What Does the Science Say About Mold?

Mold can cause health problems, especially for people with allergies, asthma or a weakened immune system.

Health effects may include:

• Allergies
• Asthma flare-ups
• Allergic rhinitis, also called hay fever
• Respiratory irritation

“It’s important to distinguish between the known health effects of mold and what is often referred to online as ‘toxic mold syndrome,’” says Dr. Shannahan. “‘Toxic mold syndrome’ or ‘mycotoxin illness’ from being indoors is not supported by evidence.”

Mold shouldn’t be ignored, especially if you have allergies or asthma. Damp or moldy areas in your home can worsen air quality and trigger respiratory symptoms, especially if you have allergies or asthma.

Scientists continue to study whether mold plays a role in symptoms, such as fatigue and chronic inflammation, but the evidence has not established a clear link.

“The mold misconception is the leap from real allergies and irritants to systemic toxicity,” says Dr. Shannahan.

When To See a Doctor

Talk with your doctor if symptoms:

• Persist for weeks or months
• Interfere with daily activities
• Are associated with a known exposure
• Occur in a damp or visibly moldy environment
• Have not been explained by previous medical testing

A thorough medical evaluation should usually come before specialized environmental testing.

“If you’re considering environmental testing, work with a board-certified integrative medicine physician or another qualified physician who can review your symptoms, exposure history and test results, and determine whether additional evaluation or treatment is needed,” says Dr. Shannahan.

When Is Testing Helpful?

Testing can be helpful when there is a specific reason to suspect an environmental exposure. Examples of validated testing include:

• Blood lead testing to evaluate possible lead exposure
• Occupational exposure monitoring in certain workplace settings
• Allergy testing for mold-related allergies

“Broad screening of otherwise healthy people is usually not recommended because many commercially marketed tests have limited clinical value,” says Dr. Shannahan. “Many of these tests come with interpretations that can lead to unnecessary or even harmful treatments.”

What Can Mold Tests Tell You?

You may have heard about:

• Mold allergy testing
• Mold antibody testing
• Urine mycotoxin testing

Some of these tests can be useful but many don’t tell you the full picture. For example, mold allergy testing can help evaluate conditions, such as asthma or allergic rhinitis. But many urine mycotoxin tests marketed directly to consumers have significant limitations.

“These tests can’t determine whether the exposure came from your environment or your diet. Trace amounts of mycotoxins naturally occur in some foods and can produce positive results in healthy people,” says Dr. Shannahan. “If you’ve been having vague symptoms, it’s understandable to look for answers. But symptoms deserve a thorough evaluation, not unvalidated testing panels.”

What To Do if You’re Concerned About Mold or Environmental Exposures

If you’re concerned about mold or environmental exposures, you can take several steps before pursuing specialized testing:

• Address environmental concerns.
• Repair leaks and address visible mold.
• Reduce dampness and condensation.
• Improve ventilation.
• Evaluate indoor air quality.
• Treat diagnosed medical conditions. Follow treatment recommendations for conditions like asthma and hypothyroidism since some can cause symptoms similar to environmental exposures.
• Get a thorough medical evaluation. Many symptoms attributed to environmental exposures can have other causes. Work with a physician who will listen to your concerns and recommend appropriate testing.
• Consider the mind-body connection. Psychological stress can contribute to physical symptoms and make existing symptoms worse. Strategies, such as deep breathing, exercise and stress management, may help.

“If your symptoms improve when you leave the environment, that information can be helpful,” says Dr. Shannahan. “If your home has dampness or visible mold, addressing those issues is important whether you get tested or not.”

How To Reduce Exposure and Support Overall Health

You can't avoid every environmental exposure. But your body already has systems built to process and remove waste, including the liver, kidneys, lungs and digestive system. Healthy habits help those systems do their job, and they can limit unnecessary exposure in the first place.

• Get enough sleep: Sleep helps with many important functions throughout the body.
• Exercise regularly: Exercise supports physical and mental well-being.
• Stay hydrated: Drinking enough fluids supports normal kidney function.
• Eat a balanced diet: Fruits, vegetables, whole grains and lean proteins contribute to long-term health.
• Avoid tobacco products: Tobacco smoke contains harmful chemicals and pollutants.
• Improve indoor air quality: Use ventilation when cooking and consider air filtration.
• Choose cleaning products carefully: Follow label instructions and avoid unnecessary chemical exposures.
• Monitor the air quality index (AQI) in your area: This can be especially important if you have asthma or other respiratory conditions.

What Should You Do Next?

If persistent symptoms are affecting your quality of life, don’t ignore them.

“Validating symptoms and pursuing real causes are not mutually exclusive,” says Dr. Shannahan. “A careful review of your symptoms, health history and environment is often more helpful than expensive tests that may not provide clear answers.”