Yes the use of rosemary oil can cause high blood pressure.
For those people suffering from high blood pressure already they should be cautious when using or taking rosemary oil because the rosemary oil can cause an increase in your blood pressure.
if you have low blood pressure then the use of rosemary oil can help increase your blood pressure which can be a good thing when you do suffer from low blood pressure.
Rosemary oil can also interfere with blood thinners and diabetes medication so if you have diabetes then you should avoid the use of Rosemary oil especially if you take blood thinner medications.
Rosemary oil is pretty safe when taken by those without diabetes or other health issues such as high blood pressure.
But Rosemary oil does sometimes cause a spike in blood pressure.