High blood pressure is called the silent killer because you usually don't have symptoms, even as your pressure is quietly causing damage to your body. Unbeknownst to you, high blood pressure may be gradually harming the ability of your heart, blood vessels, kidneys or other organs to function as they should. But sometimes, high blood pressure spikes so high that the threat is immediate, severe and potentially life-threatening. Here is what you need to know if you experience what doctors call a hypertensive crisis—when your blood pressure is high enough to be considered an emergency. What is a hypertensive crisis? A hypertensive crisis occurs when your blood pressure is so high that it can inflame your blood vessels and impair the ability of your cardiovascular system to work as it should, putting you at risk for stroke, heart attack, or other severe illness. Hypertensive crises are divided into two categories: urgent and emergency. In an urgent crisis, your blood pressure is over 180 systolic (the top number) or 110 diastolic (the lower number). However, you usually aren’t experiencing any symptoms to indicate organ damage. In an emergency crisis, your pressure is over 180 (top) or 120 (bottom) and you also have symptoms that indicate your organs are becoming damaged. Or, your blood pressure may be lower than 180/120, but it’s higher than it’s ever been and you are feeling symptoms possibly related to organ damage. These serious symptoms can include: Severe chest pain Severe headache plus confusion and/or blurred vision Back pain Nausea and vomiting Severe anxiety Shortness of breath Vision problems Nosebleeds Seizures Difficulty speaking Numbness or weakness Unresponsiveness What are the complications from a hypertensive crisis? If elevated blood pressure remains untreated, you face the risk of a variety of potentially severe consequences. Extremely high blood pressure can cause a stroke or heart attack, damage to your eyes, damage to your kidneys (including kidney failure), cognitive problems like memory loss or loss of consciousness, an aortic dissection (a tear in the main artery branching off your heart), or fluid in your lungs. Because the threat to your health is so severe, seek medical attention if your blood pressure is extremely high and you are experiencing any of the symptoms listed above. What causes extremely high blood pressure? There are a variety of reasons for blood pressure to shoot up. Forgetting to take your medicine can lead to your pressure getting out of control. You may have an interaction between medications you are taking. If you're pregnant, you may be experiencing a condition called preeclampsia. Or the blood pressure spike could be caused by another medical condition. No matter the cause, it’s important to get help as soon as possible. Seek medical attention if your blood pressure gets above 180 (top) or 110 (bottom). It's critical for doctors to evaluate potential organ damage and reverse the process before it's too late.