Seasonal Conditions


Hay Fever

Itchy eyes and runny nose may be signs of hay fever. In Japan, many people suffer from allergies to specific pollen types, with Japanese cedar and cypress among the most common. Allergy medicines can be purchased at drugstores, but it is a good idea to visit a clinic (otolaryngology or an allergy specialist) to receive treatment or undergo an allergy test. Face masks and protective glasses can help prevent symptoms.



Japan’s summer is hot and very humid, making heatstroke a real concern, particularly for young children and the elderly. Symptoms include headache, nausea and dizziness, and in extreme cases, loss of consciousness. Heatstroke and heat fatigue can be caused by physical activity under the sun, spending prolonged periods outside, and by sudden temperature changes when moving between air conditioned spaces and outdoors. It is important to stay hydrated throughout the day, and sports drinks are especially useful to replace electrolytes lost through sweating.

Dengue fever

Dengue was relatively rare in Japan until a number of cases were confirmed in parts of the country in 2014. Transmitted through mosquito bites, its symptoms include a high fever and severe joint pain. As there is no vaccine for dengue, the best course of action is to avoid infection in the first place. Mosquito repelling sprays can be bought at drugstores and are very effective.



Colds and flu are prevalent in winter, and spread easily in crowded cities. Medicines to treat symptoms can be bought at convenience stores and drugstores but are likely to be weaker than North American and European counterparts. If your symptoms are severe, it is best to see a doctor, as prescription medications will be stronger. Many businesses and schools will advise people with the flu to stay at home to prevent transmission of the disease. If you must leave the house, wear a medical face mask to protect others from infection. Influenza vaccines are available each year beginning in autumn.


Norovirus is a virus that is particularly common in winter, and causes vomiting, diarrhea and fever. Symptoms tend to last around a week. To prevent dehydration while infected it is important to drink plenty of fluids. To help prevent infection, wash your hands with soap and warm water and make sure all food is heated through before eating, particularly shellfish. Kitchen implements should be washed well in hot water.