Nasal allergy symptoms include sneezing, runny or stuffy nose, itching and dark circles under the eyes.

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Do your symptoms get worse in the early spring or late summer or fall? Do you feel like you have frequent colds that just won't go away?

Your "cold" may not be a cold at all. It may be nasal allergies, also called hay fever, chronic nasal allergy, or allergic rhinitis. These are allergies that affect your nose, eyes, ears and throat.

If you have nasal allergies you're more sensitive than others to certain substances. These substances are usually considered harmless, such as pollen or mold. They cause an exaggerated reaction in your nose, eyes, and sinuses, triggering symptoms such as stuffiness, itching, runny nose, and watery eyes.

The substance that causes the immune system to overreact is called an allergen. It takes more than just one exposure to an allergen to trigger nasal allergies. People with nasal allergies become sensitized, or allergic, to a substance only after repeated exposure. This can take weeks, months, or even years. Once you're sensitized, though, allergy symptoms develop every time you're exposed to that allergen. That's because your body mistakes a harmless substance for a harmful invader and wages battle against it.

If you have nasal allergies, you're sensitive to allergens that are specific to you. So what bothers you and causes your stuffy or runny nose, itchy eyes, and other symptoms may not bother someone else, even someone with nasal allergies. For instance, you may be sensitive to tree pollen. Someone else with nasal allergies may be sensitive to pet dander or dust mites.

See the next page to learn more about the different types of nasal allergies.