A runny nose in Japan can have many causes, and the treatment approach differs significantly depending on which one is at play. Is it Japan's legendary cedar pollen season? A common cold picked up on the Shinkansen? Dry heated air in your hotel room? Or sinusitis that needs prescription medication? This guide walks you through the differences and your options.
Cedar Pollen Season: Japan's Most Famous Allergen
Sugi-kafunshō (スギ花粉症, cedar pollinosis) is one of Japan's most widespread health conditions, affecting an estimated 40% of the population. The pollen season runs from late January through April, with peak levels typically in February and March in central Japan.
Even tourists who have never experienced hay fever before can develop reactions upon first heavy exposure to Japanese cedar pollen. Symptoms include:
- Watery, runny nose (水っぽい鼻水)
- Frequent sneezing
- Itchy, watery eyes
- Nasal congestion
- Mild fatigue
The Japanese Meteorological Agency publishes daily pollen forecasts (花粉情報), and many weather apps include pollen count data. On high-pollen days, counts can reach into the thousands of particles per square centimeter.
Common Causes of Runny Nose in Japan
Viral rhinitis (common cold) — the most common cause year-round. Typically accompanied by sore throat, mild fever, and cough. Nasal discharge often changes from clear to yellow-green as the infection progresses.
Allergic rhinitis — from cedar or cypress pollen (spring), house dust mites (year-round), mold, or pet dander.
Sinusitis — inflammation of the sinus cavities, which can follow a cold. Symptoms include facial pain/pressure, yellow or green discharge, post-nasal drip, and reduced sense of smell. May require antibiotics if bacterial.
Vasomotor rhinitis — non-allergic nasal congestion triggered by temperature changes (particularly common when moving between cold outdoor air and heated interiors in Japan's winter).
Dry air — Japan's winter heating dries out nasal passages, causing irritation and excessive mucus production.