What a Sudden Drop in Blood Pressure Means

Elizabeth Molina Ortiz, MD, MPH, is a board-certified specialist in family medicine and is the former medical director of a community health center.

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A sudden drop in blood pressure, also called hypotension, can occur for any number of reasons. Some may be of no real concern, while others may be a sign of a potentially life-threatening condition.

This article will cover the various causes of low blood pressure, possible symptoms, and treatment options.

Symptoms

Blood pressure is measured in millimeters of mercury (mmHg). Hypotension is usually defined as a systolic (upper) value of 90 mmHg and a diastolic (lower) value of 60 mmHg. Normal blood pressure is considered 120/80 mmHg or below.

However, blood pressure that's too far below that number can lead to problems. Generally speaking, the lower and faster the blood pressure drops, the more severe the symptoms will be. The extent of the drop in pressure also plays a role.

For example, if you have high blood pressure (hypertension) and the pressure suddenly drops to below 90/60 mmHg, you are more likely to experience noticeable symptoms than if it were to drop from, say, 110/70 mmHg.

Sudden (also called acute) drops in blood pressure can cause symptoms ranging from mild lightheadedness and fatigue to severe heart rhythm problems and respiratory distress.

When blood pressure drops suddenly, blood flow to the body decreases. This starves the body of the oxygen and nutrients that it needs to function. The lack of blood flow to the brain especially triggers symptoms.

Common signs include:

Other symptoms that can occur include chest pain, shortness of breath, irregular heartbeat, hives, fever, indigestion, and vomiting. These tend to be associated with the condition that caused the drop in the first place.

Symptoms of Low Blood Pressure

Extreme hypotension can severely deprive the brain and vital organs of oxygen and nutrients, leading to shock. Shock can progress rapidly. Symptoms include:

Call 911 or go to your nearest emergency room if signs of shock develop. If left untreated, shock can lead to permanent organ damage, cardiac arrest, and even death.

Causes

There are several possible causes of hypotension. Some of them can overlap, making the diagnosis more difficult. Causes include:

Hypovolemia is a term used to describe reduced blood volume. This is the most common cause of hypotension. It can occur if you are not getting enough fluids or if your body is losing too much fluid.

Common causes of hypovolemia include:

Hypovolemic shock occurs when you lose more than 20% of your blood volume for any reason. A loss at this level makes it impossible for the heart to pump a sufficient amount of blood through the body.

Even if your blood volume is normal, there are conditions that can reduce the body's ability to pump blood. This condition is known as decreased cardiac output.

It can occur as a result of a heart problem, endocrine (hormonal) dysfunction, and certain medications. Sudden changes in cardiac output can cause a sudden drop in blood pressure.

Causes of decreased cardiac output include.

Vasodilation describes the sudden widening of blood vessels. As the blood vessels get wider, blood pressure continues to drop.

Common causes of vasodilation include:

A hypotensive syndrome is the term used when more than one factor causes a sudden drop in blood pressure. Usually the person has an underlying condition that is then triggered by doing something such as standing up after sitting or experiencing severe emotional distress.

Hypotensive syndromes tend to come on suddenly, sometimes with dramatic symptoms, including extreme dizziness and unconsciousness.

Some common hypotensive syndromes include:

In people with certain diseases or conditions, doing something as simple as rising from a chair or turning the head can trigger a sudden drop in blood pressure. This is known as a hypotensive syndrome.

Diagnosis

A blood pressure cuff called a sphygmomanometer can tell you how low your blood pressure is, but it can't tell you what caused the sudden drop.

For this, the doctor will need to review your medical history, family history, current symptoms, and medications. Then they will perform some of the following tests to figure out the cause:

Treatment

The treatment of acute hypotension varies based on the underlying cause. If the condition is not a medical emergency, you should either sit or lie down immediately and raise your feet above heart level. If you are dehydrated, you should replenish lost fluids and seek immediate medical attention if the symptoms are severe.

If hypovolemic or hemorrhagic shock is involved, you may be given an intravenous (IV) saline solution or a blood transfusion. Septic shock may require IV antibiotics, while anaphylactic shock requires epinephrine (adrenaline).

If hypotension is related to extreme vasodilation or decreased cardiac output, medications such as vasodilators (like midodrine) or drugs to stimulate the heart (like digitalis) may be prescribed to improve heart function and output.

People with severe postural hypotension may benefit from the use of the anti-inflammatory steroid fludrocortisone.

Compression socks are often prescribed for people with orthostatic hypotension to prevent the pooling of blood in the legs. Wearing them keeps more blood in the upper body.

Summary

A sudden drop in blood pressure can occur for a variety of reasons. Some of these are not serious. In some cases, though, it may be a sign of something more serious, and even life-threatening. Serious underlying causes usually have other symptoms.

Hypotension can often be treated successfully. The underlying cause, on the other hand, may require extensive treatment by a specialist, such as a cardiologist, neurologist, or endocrinologist.

A Word From Verywell

It is important not to ignore signs of hypotension. This is especially true if the drop is sudden and severe. By seeing a doctor and pinpointing the cause of acute hypotension, you can be treated appropriately and avoid any long-term harm to your health.

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