Allergy Day

What Is Allergy Day?

Every February 20th is "Allergy Day" in Japan. On February 20, 1966, Japanese immunologists Dr. Kimishige Ishizaka and Dr. Teruko Ishizaka — a husband-and-wife research team — announced their discovery of Immunoglobulin E (IgE), the antibody responsible for triggering allergic reactions. Their groundbreaking finding transformed the scientific understanding of allergy and paved the way for modern allergy treatments. In recognition of this milestone, the Japan Allergy Foundation established Allergy Day in 1995.

The Discovery That Changed Allergy Science

Before the Ishizakas' discovery, the mechanism behind allergic reactions was poorly understood. Scientists knew that allergens triggered symptoms, but the molecular "messenger" linking exposure to reaction was unknown. By isolating IgE — a previously unidentified class of antibody — the Ishizakas provided a unified explanation for conditions ranging from hay fever and asthma to food allergies and anaphylaxis. Their work earned them the Lasker Award in 1974, often considered a precursor to the Nobel Prize.

Allergies in Japan Today

Japan has one of the world's highest rates of allergic disease. Cedar pollen (スギ花粉, sugi kafun) season, which peaks in February through April, affects an estimated 40% of the Japanese population with hay fever symptoms. Food allergies — particularly to eggs, milk, wheat, shrimp, and peanuts — affect millions of children and adults. Allergy Day serves as a reminder to increase public awareness, support ongoing research, and improve access to diagnosis and treatment.

Living with Allergies

For the millions of people in Japan affected by allergic conditions, daily life requires careful management — from reading food labels meticulously to carrying epinephrine auto-injectors, monitoring pollen counts, and adapting homes and workplaces to minimize allergen exposure. Medical advances since the Ishizakas' discovery — including immunotherapy, biologics targeting IgE, and precision allergy testing — have significantly improved quality of life for allergy sufferers.

Fun Facts About Allergies

• Sugi pollen season: Japan plants vast cedar forests after WWII for timber, but as demand for domestic timber fell, the trees matured and began releasing enormous amounts of pollen — turning a forestry decision into a public health challenge.
• IgE-targeted therapy: Omalizumab, a monoclonal antibody that blocks IgE, is now used to treat severe asthma and chronic hives — a direct descendant of the Ishizakas' research.
• Ishizaka's legacy: Kimishige Ishizaka was awarded the Order of Culture (文化勲章) by the Japanese government in 1990 for his contributions to science.

Understanding the Body That Protects — and Overreacts

February 20th is an opportunity to learn more about the immune system and the complex ways it interacts with the world around us. The Ishizakas' discovery reminds us that fundamental science — curiosity-driven research into the body's own mechanisms — has the power to relieve suffering for millions.