Many people breathe a sigh of relief when spring shyly offers its first green buds and promises new life after a frigid white winter. Others reach for their inhalers, nasal sprays, and antihistamines, braced for their breathing to get hijacked by allergic sniffles and wheezes. Allergy and asthma symptoms plague roughly one out of five Americans, and they continue to be on the rise.

There are many theories about why the number of allergy sufferers has skyrocketed, and many of them point to environmental changes. For example, the “hygiene hypothesis” blames today’s sterile, industrialized lifestyle for reducing people’s exposure to a well-rounded assortment of germs that are actually needed to induce the normal development of immune cells.

Another theory suggests that global warming has lengthened allergy seasons. Ragweed season alone has grown by four weeks in the past decade, which means an additional month of itchy throats and eyes. Others point to the types of trees and plants that adorn American streets and backyards. Most are male plants, preferred because they lack unkempt pods and fruits. The problem is that they pump more pollen into the air.

Pollen is made up of small particles that are spread easily by the wind. In the spring they originate from trees and in early summer they come from grasses. Weeds are the source of pollen in late summer and early fall.

The first time that these tiny grains drift into a susceptible person’s nose and contact their mucous membranes, a cascade of immune signals leads to the formation of IgE antibodies. These antibodies act like airport customs officials, scanning for intruders. When pollen is detected, a red alert is signaled and backup is called forth in the form of a surge of histamine and other inflammatory mediators. Next comes the dilation of blood vessels, mucous secretion and nerve stimulation, resulting in sneezing, itching, congestion, a runny nose, and watery eyes.

Whether a person becomes sensitized to these allergens depends on their genetics and environmental factors. Other common types of allergens include dust, mold, animals, and foods. While some people have unmistakable allergy symptoms, others may have subtle chronic symptoms like persistent congestion or post-nasal drip that they shrug off as “normal” without realizing the actual impact. Still others may have less apparent symptoms such as digestive upset, wheezing or shortness of breath, or even fatigue or anxiety.

Of the numerous approaches to allergy treatment, the first step is avoidance. Spring pollen sufferers should stay indoors and use air conditioning in lieu of open windows. Those sensitive to dust should wash all bedding weekly in hot water and encase mattresses, pillows, and box springs in impermeable covers. People allergic to mold should avoid damp basements and raked leaves, and combat mold growth at home.

Other tips include keeping rugs and pets out of bedrooms, and using a HEPA filter. Medications commonly used in the treatment of allergies include antihistamines, inhaled corticosteroids or bronchodilators and decongestants. More natural options include: quercitin, which decreases histamine; bromelain and stinging nettles, which calm the inflammation cascade; and n-acetyl cysteine (NAC), which dissolves mucous.

Some people find that dietary changes, such as eliminating foods containing gluten and dairy, help to lessen allergy symptoms as well. Other options include acupuncture, homeopathy, and immunotherapy, which involves regular injections of allergens.

Health care providers can offer relief to those already affected by pollen, even by simply bringing awareness to symptoms that can then be treated, rather than tolerated.

Sarah J. Byrne, M.D., is a Functional Medicine physician at Visions HealthCare, 910 Washington St., in Dedham. Allergy services are also available at Visions HealthCare in Wellesley at 170 Worcester St. For more information about allergy testing and treatment options, visit VisionsHealthCare.com or call 781-431-1333.