They can include severe headaches, vision problems, chest pain, nosebleeds, blood in the urine, and nausea and vomiting.
Malignant hypertension can be prevented, however, by checking blood pressure and keeping it under control if it is high.
According to the NHS, normal blood pressure is considered to be between 90/60mmHg and 120/80mmHg.
High blood pressure is considered to be 140/90mmHg or higher.
Malignant hypertension is considered to be 180/120mmHg or higher.