Tachycardia from Minoxidil?

What is the likelihood minoxidil caused an episode of tachychardia where patient is a healthy 48 year old female with no cardiac history or risk factors who used it on her scalp for a week prior and whose symptoms did not recur upon cessation of use?

There may be a direct association between tachycardia (fast heart rate) and minoxidil (which is a hypotensive agent that drops blood pressure). Many people complain of dizziness with this drug and what they are probably experiencing is a small drop in their blood pressure. When blood pressure drops, the first thing the body does to compensate for it is to increase the heart rate, so your symptoms fit nicely into the physiology of the cardiovascular system.