Japan's weather, pollution levels, and allergen environment differ significantly from most tourists' home countries, making respiratory symptoms like cough surprisingly common. A post-nasal drip from Japan's cedar pollen season (February–April), the dry heated air of winter ryokans, or a cold picked up on a crowded Shinkansen — all are frequent triggers. This guide helps you figure out what is causing your cough and what to do about it.
Common Causes of Cough in Japan for Tourists
Common cold (風邪, kaze) is the leading cause, especially in winter. Japan's crowded public transport and indoor environments make transmission easy.
Cedar pollen allergy (スギ花粉症) runs from late January through April. It causes runny nose, itchy eyes, and persistent cough in susceptible individuals. Even people who have never had allergies before can react upon first significant exposure.
Dry air in winter-heated rooms, particularly in older hotels and ryokans, causes throat irritation and night-time cough.
COVID-19 and influenza remain active in Japan year-round, with peaks in winter. Both produce prominent cough.
Post-nasal drip from any nasal inflammation drips onto the throat, causing a persistent, often worse-at-night cough.
Gastroesophageal reflux disease (GERD) cough is triggered by spicy or rich Japanese food and often worsens after lying down.
Environmental irritants — cigarette smoke (Japan still permits indoor smoking in some venues), incense at temples, and industrial pollution in certain urban areas — can irritate airways.
Pertussis (whooping cough) and mycoplasma pneumonia are less common but cause prolonged, severe cough and require antibiotics.