A blood pressure of 120/90 mmHg is an abnormal blood pressure and by the definition of hypertension should be critical hypertension.
The definition of hypertension is that a diagnosis of hypertensive disease is made when correct blood pressure measurements are taken and three or more blood pressure measurements on a non-same day reveal a systolic blood pressure of ≥140 mmHg, and/or a diastolic blood pressure of ≥90 mmHg. Therefore, one measurement alone is not sufficient to diagnose hypertension.
However, if it is a correct blood pressure measurement and is at 120/90 mmHg on multiple occasions, the diastolic blood pressure has met the diagnostic criteria for critical hypertension, and therefore the diagnosis of hypertension is made. This hypertension is predominantly characterized by increased diastolic blood pressure, and it is important to help find possible factors, to help find possible interventions in lifestyle, to make life adjustments, and to observe for a period of time.
If there is no significant change after a long period of improvement, it is recommended to seek medical attention and appropriate intervention under the supervision of a doctor to bring down the diastolic blood pressure.