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Severe Hypertension or Hypertensive Crisis

What Is The Definition Of Severe Hypertension Also Known As Hypertensive Crisis?

Having blood pressure readings categorised in the range of ‘severe hypertension’ or ‘hypertensive crisis’ can pose a serious health risk. Medical confirmation and attention should be sought at the earliest opportunity for anyone with readings at these levels. For blood pressure readings to be defined as severe hypertension you would generally need to be recording systolic readings greater than 180mmHg and/or diastolic readings greater than 110mmHg. Whereas on the American College of Cardiology & American Heart Association (ACC-AHA) hypertension scale, the threshold to be categorised as having hypertensive crisis would need readings exceeding 180mmHg systolic and/or 120mmHg diastolic.

Systolic refers to the higher pressure created when the heart contracts on a beat and forces blood out to the body, while diastolic refers to the lower pressure when the heart is dilated and relaxed between beats. mmHg are the units of measurement which refer to millimetres of mercury, you can read more about why blood pressure is measured in these units here.

The sequence of escalating blood pressure categorisations above the normal or normotension range is shown below:

  1. ‘Elevated’ or ‘Elevated Normal’
  2. ‘Prehypertension’ (no longer used in the United States ACC/AHA scale since 2017)
  3. ‘Hypertension Stage 1’
  4. ‘Hypertension Stage 2’
  5. Severe Hypertension’ or ‘Hypertensive Crisis
  6. ‘Hypertensive Emergency’

Severe hypertension and hypertensive crisis levels are higher than hypertension stage 2 but below, although intertwined with, hypertensive emergency. The meaning of hypertensive emergency refers to the situation where organ and tissue damage is occurring due to extremely high blood pressure. It requires immediate hospitalisation as it leads to a failure of normal physiological functioning of the body with a high chance of irreversible damage and death.

What are the Symptoms of Severe Hypertension / Hypertensive Crisis?

High blood pressure may still not present symptoms even at these extreme levels, although is is more likely than in lower ranges. With blood pressure up at these levels, blood vessels can become inflamed damaging them, fluid or blood may be forced out from them causing inefficiency in the ability of the heart to successfully pump blood, and therefore oxygen around the body.

Some symptoms which may be experienced include:

  • Severe anxiety
  • Being short of breath
  • Having seizures
  • A feeling of Nausea
  • Severe headaches
  • Becoming unresponsive
  • Fluid collecting on the lungs (pulmonary oedema) or a fluid build-up in tissues
  • Dizziness
  • Chest pains

Organ damage may or may not occur with blood pressure up at these levels and intravenous or oral medications are usually required potentially combined with hospitalisation.

What Are Some Of The Causes Of Hypertensive Emergency?

Some potential causes that can drive blood pressure up quickly to these levels that pose a risk to damaged organs and tissues include:

  • Heart Attack
  • Ruptured aorta artery (aneurysm)
  • Heart failure
  • Pregnancy eclampsia (convulsions)
  • Stroke
  • Kidney failure
  • Interactions of combined medications that are incompatible
  • Not taking prescribed blood pressure medication


If your blood pressure readings are coming in around these very high levels, you should seek confirmation of an accurate reading from a medical professional right away. Blood pressures around these levels tend not to be effectively treated with lifestyle changes compared lesser hypertensive ranges. There is an urgency to reduce the pressure as quickly as possible and so oral or intravenous medication is the most likely path of treatment, potentially combined with a period of hospitalisation if there is evidence of organ damage occurring.