Understanding Low Blood Pressure (Hypotension)

While high blood pressure (hypertension) often gets the most attention, blood pressure that is too low—a condition known as hypotension—can also impact your well-being.

Defining the Numbers

Blood pressure is measured by the force of blood against your artery walls. It is recorded using two numbers:

Systolic (Top Number): The pressure when your heart beats.
Diastolic (Bottom Number): The pressure when your heart rests between beats.

A reading is generally considered low blood pressure if it is 90/60 mmHg or lower.

When is Low Blood Pressure a Problem?

For many people, a low reading is simply their “normal” and is actually a sign of excellent cardiovascular health, especially in athletes. However, it becomes a medical concern if it leads to inadequate blood flow to the brain and other vital organs.

Common Symptoms

Dizziness or Lightheadedness: Often felt when changing positions.
Fainting (Syncope): A sudden, temporary loss of consciousness.
Blurred Vision: Difficulty focusing due to decreased blood flow.
Fatigue or Lack of Concentration: Feeling sluggish or “foggy.”
Shock: In extreme cases, blood pressure drops so low that organs begin to fail. This is a life-threatening emergency.

Postural Hypotension

One of the most common forms of low blood pressure is orthostatic hypotension. This occurs when your blood pressure drops suddenly as you stand up from a sitting or lying position. Gravity causes blood to pool in your legs, and if your body doesn’t adjust quickly enough, you may feel a brief “head rush” or dizzy spell.

Causes and Triggers

If your low blood pressure isn’t “normal” for you, it might be caused by:

Dehydration: Losing more fluid than you take in reduces blood volume.
Medications: Certain drugs for high blood pressure, heart conditions, or depression can lower pressure too much.
Heart Problems: Extremely low heart rates or valve problems.
Endocrine Issues: Thyroid conditions or low blood sugar.
Severe Infection or Allergic Reaction: Conditions like sepsis or anaphylaxis cause a dangerous drop in pressure.