Blood pressure 120/40 can often indicates failure tonometer (a device for measuring blood pressure).
If BP 120/40, you should measure blood pressure on the opposite hand, then repeat the measurement after 10-15 minutes. In addition, if possible, you need to check the results of blood pressure measurement using another tonometer – it’s not necessary to use medicines to change blood pressure.
If you got the results of blood pressure 120 over 40, but you feel good – no need to take any action to stabilize the blood pressure. If you feel fatigue, weakness, drowsiness, headache – you need to consult a doctor for diagnosing the health.