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Allergies arise if the body's immune system overreacts to certain foreign substances (allergens) that are normally harmless in most people.

Common allergens include pollens, fungal spores, house-dust mites, and animal epithelial materials but can also include drugs, biologic products, and insect venoms.

How a person reacts to an allergen depends on how they come in contact with it. In many people, allergic reactions occur on the skin and in the airways and mucous membranes. Symptoms usually start quickly after contact with the allergen. In some cases, it takes a few hours or days for the reaction to happen. Symptoms can be mild or a real nuisance with a considerable effect on everyday life.

The following webpages have information on some of the most common seasonal and non-seasonal allergens:

They also provide preventive strategies to help you avoid exposure to these substances.

Asthma is a chronic lung disease and one of the most common chronic health conditions in the U.S. Some allergens can increase the severity of asthma symptoms in people who are sensitive to them.

Information contained on these webpages is provided for educational and informational purposes only and should not be used to guide the diagnosis or treatment of any medical condition without the advice and supervision of a licensed, qualified health care provider.

What is NIEHS Doing?

NIEHS Research Efforts

Nuclear Magnetic Resonance Group - Geoffrey Mueller, Ph.D., leads this group and conducts research on the molecular determinants of allergic disease.

The science emerging from Mueller’s laboratory has the potential to help millions of people. Read about how his work may reshape the future of allergy treatments in the NIH Record.

For information on other related research performed at NIEHS, visit the Division of Intramural Research Immunity, Inflammation, and Disease Laboratory, which focuses on understanding how the human body protects itself against environmental exposures such as allergens.

Cross-Divisional Inflammation Faculty - Inflammation, an immune system response to internal or external factors such as allergens, can be helpful or damaging. This faculty works to inform NIEHS and the field about the current state of the science on inflammation, identify knowledge gaps, address key unresolved research questions, and other efforts.

Further Reading

Stories from the Environmental Factor (NIEHS Newsletter)

Additional Resources

  • Healthy Buildings, Healthy People, Healthy Planet (January 2022) - Joseph G. Allen, D.Sc., an associate professor at the Harvard T.H. Chan School of Public Health, discusses his research on indoor air quality and health. He also offers strategies people can use to promote healthy buildings.
  • Allergy Seasons Are Worsening and Climate Change Is Playing a Significant Role (2021) - Research news release from the Columbia University Mailman School of Public Health.
  • American Lung Association - The American Lung Association is the leading organization working to save lives by improving lung health and preventing lung disease.
  • Environmental Wellness Toolkit - What surrounds you each day in your home, work, or neighborhood and the resources available to you can affect your health. You can’t always choose what’s in the environments you live, work, or play in. But taking small steps to make your environments safer and limiting your exposure to potentially harmful substances can help keep you healthier.
  • Food Allergy - National Institute of Allergy and Infectious Diseases (NIAID) is the lead institute at the National Institutes of Health conducting research on food allergy, a condition that affects approximately 5% of children and 4% of adults in the United States. Read on to learn more about food allergy and the steps NIAID is taking to address this growing problem.
  • National Library of Medicine MedlinePlus: Allergy - A compilation of links to various resources that help with allergy treatment, diagnosis, and prevention.
  • Talking to Your Doctor - Resources from NIH - You can play an active role in your health care by talking to your doctor. Clear and honest communication between you and your physician can help you both make smart choices about your health.

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