My father has high blood pressure. The higher pressure could go all the way up to 180. But with the help of pressure lowering medicine, it is usually maitained in normal range.
But for sevral years,for no obvious reason, he suddenly had high very high fever (40 oC) and at the same time his body was shaking uncontrollably. But after medication to lower the fever, his blood pressure went to normal right away.

My question is: What is the cause? High blood pressure leading to fever or fever leading to high blood pressure? Thanks