At the clinic you can get a prescription for doxycycline. The charge is not covered by Japanese Health Insurance, but its cost is reasonable. If you stay two weeks in the country, you will have to start the drug two days before your departure, and then you can stop anytime after you come back home if you feel you are fine (four weeks is the longest limit, if you are a very careful person). The charge is about 3,000 JYN for the prescription of doxycycline for 6 weeks.
🙂🙂Notes about taking doxycyline:🙂🙂
#1. Doxycycline is not a perfect protection against malaria.
#2. Doxycycline can hide the symptoms of other infections you may have (e.g. appendicitis, cholera, etc.), which could lead to a delay in the diagnosis of the disease.
#3. There are three phases of possible side-effects.
#4. There is no definite period that you should take the drug. (You have to decide when to stop by yourself. Four weeks after your return from the malaria-affected area is the longest time you should take the medicine.)
Still...
avoiding mosquitoes is the best precaution
against malaria!