A tree pollen allergy is a sign that your immune system is prone to make mistakes. When you were first exposed to the pollen of trees, your body thought it was being invaded by something dangerous and therefore flagged tree pollen as a harmful substance. Ever since then, your body has been on the lookout for tree pollen. When you breathe in the small particles that trees release in order to fertilize each other, your immune system sends out an antibody called immunoglobulin E to neutralize the allergen. As it delivers the allergens to your mast cells for destruction, chemicals are released. One of these chemicals is histamine, and it's responsible for most of the tree pollen allergy symptoms you experience.

Typically, trees begin pollinating in the early spring. You'll normally feel allergic symptoms as soon as you breathe in the pollen or it lands on your nasal membranes. Such symptoms include a runny nose or congestion; watery or itchy eyes; sneezing; coughing; itchy nose, throat or roof of mouth; sinus pressure; and occasionally even a decreased sense of taste or smell. For some people, tree pollen allergies cross react with the proteins in certain foods. Oral allergy syndrome, or pollen-allergy syndrome as it's sometimes called, happens when your body confuses certain fresh fruits, vegetables or nuts with the pollen of the trees you're allergic to. When that happens, you'll experience a tingling, itching or swelling around your mouth as you eat those foods.

Tree pollen allergy symptoms can normally be treated with over-the-counter or prescription medications. Antihistamines relieve many symptoms by blocking the histamine your body releases in the allergy battle. Decongestants clear up your nasal passages, as do nasal cortisone sprays. The sprays also work to reduce swelling in your nose.