Allergies can result in a number of symptoms, whose severity can vary from person to person. One symptom of an allergy is nasal congestion, which is the inflammation of the nasal passages. This inflammation results in watery nasal discharge and itching of the nose and eyes. Allergic rhinitis is one of the most common illnesses in the U.S. and affects about 20 percent of the population. People with this condition develop rhinitis symptoms following their exposure to allergens such as dust, dander, certain seasonal pollens, mold and animals.

Some symptoms of rhinitis include repetitive sneezing, rhinorrhea (runny nose), post-nasal drip, nasal congestion and itchy eyes, ears, nose and throat. Other symptoms may include general fatigue, wheezing, teary eyes, sore throat, a loss of taste or smell and difficulty concentrating. Rhinitis can also lead to a chronic cough, mainly caused by post-nasal drip.

Exposure to an allergen triggers the body to produce inflammation-causing histamine in excessive amounts. The histamine causes the blood cells in the nasal region to dilate, resulting in the production of mucous, which in turn leads to other allergic rhinitis symptoms.

Medications are available to treat nasal congestion. Low-dose steroid nasal sprays and nose drops are common and effective, but they require continuous use for long-term efficacy. Decongestant tablets and sprays may provide relief from blocked noses but can only be used temporarily. Antihistamine, which blocks the body's production of histamine, may also be effective, particularly for nasal congestion caused by hay fever.

Like any allergy symptoms, the best way to control rhinitis and nasal congestion caused by allergies is by eliminating exposure to the guilty allergens. To do this, you will first need to identify what exactly is causing the allergy and then remove it from your immediate environment.