Abnormally low blood pressure (hypotension) can cause dizziness and fainting. In severe cases, low blood pressure can be life-threatening.
A blood pressure reading lower than 90 millimeters of mercury (mm Hg) for the top number (systolic) or 60 mm Hg for the bottom number (diastolic) is generally considered low blood pressure.
The causes of low blood pressure can range from dehydration to serious medical disorders. It's important to find out what's causing your low blood pressure so that it can be treated.
Shock
Extreme hypotension can result in this life-threatening condition. Signs and symptoms include:
- Confusion, especially in older people
- Cold, clammy, pale skin
- Rapid, shallow breathing
- Weak and rapid pulse
It can be helpful to keep a record of your symptoms, when they occur and what you're doing at the time.
Conditions that can cause low blood pressure
- Lack of nutrients in your diet. A lack of the vitamin B-12, folate and iron can keep your body from producing enough red blood cells (anemia), causing low blood pressure.
Types of low blood pressure
- Low blood pressure on standing up (orthostatic or postural) hypotension).
- Low blood pressure after eating (postprandial hypotension).