Allergic reactions to eucalyptus pollen occur rarely in the United States, due to its lower airborne prevalence and a relatively small tree population. Native to Australia, eucalyptus, or gum, trees were introduced to the Western Coastal U.S. and are cultivated sparsely in other areas. Hay fever sufferers in California, Oregon and Washington, however, may become sensitized to eucalyptus pollen. Allergy symptoms arise during the spring reproductive season, but the Pollen Library notes that odor responses to eucalyptus leaves and essential oils can occur any time.
Inhaling eucalyptus pollen allergens makes some human immune systems release chemicals that trigger hay fever symptoms. Touching the trees' oily leaves or sap-laden bark may also cause allergy symptoms that often begin with itching. According to the University of Maryland (UM) Medical Center, inflammation of the mucous membranes creates sensations of itchiness. Patients may experience itchy mouth, throat and nose soon after allergy exposure.
As the mucous membranes of the eyes become affected by pollen, conjunctivitis allergy symptoms develop. Patients' eyes may grow red and overflow with tears. Itching often spreads to the eyes and may intensify if patients rub more allergens into them. The UM Medical Center relates that inflammation brought on by hay fever can also cause the eyelids to swell or dark circles to form beneath the eyes.
The inflammation and excess mucus production and drainage that accompany hay fever wreak havoc on the respiratory system. Allergy patients who inhale eucalyptus pollen may experience swelling in the throat and nasal passages as the body attempts to shut out the source of allergens. As the Cleveland Clinic relates, sneezing begins as a means of clearing out the irritants in the nasal membranes and throat. People suffering from a contact or odor response to the intense eucalyptus fragrance may share these effects. These respiratory allergy symptoms make breathing difficult. The accumulation of mucus in the nasal and sinus passages marks a complete respiratory reaction to the pollen allergens. A runny nose may alternate with stuffiness and congestion until the allergen exposure ends.
Pain and Fatigue
Prolonged allergic reactions that last through a pollination cycle take a toll on patients' overall health. Swelling of the airways and irritation from mucus drainage can cause a sore throat and a dry cough, notes the UM Medical Center. The pressure from sinus congestion and inflammation can create facial pain, tenderness and headaches. A lengthy or particularly severe allergy attack may cause patients to feel fatigue even after other symptoms have passed.