High blood pressure, or hypertension, generally has either no outward symptoms; if they are there, they may be very vague and mild. In most of the cases, people are unaware of the disease until a doctor happens to check their blood pressure as a part of a routine check-up. In fact, hypertension is called a silent killer. The only way to know about the existence of hypertension is to get one's blood pressure checked. Therefore, many doctors advise that it is advisable to get one's blood pressure checked regularly.

However, there are certain mild or vague symptoms that may act as pointers. For example, a patient may have a constant discomfort, which is, not feeling comfortable with himself. He may not be able to identify what is wrong, but strongly feel that something is wrong. If left unattended, he may become worse.

Some patients experience a mild or heavy, consistent headache, especially a pulsating headache behind the eyes. Dizziness and flushed/red face are also symptoms of hypertension. People with severe hypertension experience blurred or impaired vision and fits or black outs.

Other symptoms such as fatigue, nervousness, palpitations, racing or irregular heartbeats, chest pain suggest hypertension caused by other conditions. Bleeding in the retina, also known as retinal hemorrhage, or from the nose (Epistaxis) may be indicative of high blood pressure. Cramping in the leg while walking, excess perspiration, nausea, vomiting, frequent urination, shortness of breath and restlessness are other possible symptoms of hypertension. In rare cases, the high blood pressure may cause heart attacks, kidney failure or brain swelling, which can lead to drowsiness and coma. Disturbed levels of consciousness such as sleepiness and even seizures in severe cases of hypertension, may occur.

These symptoms may sometimes manifest in a patient with normal blood pressure also. If left untreated, hypertension can cause damage to the brain, eyes, kidneys, and heart.