Low blood pressure occurs when blood pressure is much lower than normal. This means the heart, brain, and other parts of the body do not get enough blood. Normal blood pressure is mostly between 90/60 mmHg and 120/80 mmHg.

The medical name for low blood pressure is hypertension.

Causes
 
Blood pressure varies from one person to another. A drop as little as 20 mmHg, can cause problems for some people. There are different types and causes of low blood pressure.

Severe hypotension can be caused by sudden loss of blood (shock), severe infection, heart attack, or severe allergic reaction (anaphylaxis).

Orthostatic hypotension is caused by a sudden change in body position. This occurs most often when you shift from lying down to standing. This type of low blood pressure usually lasts only a few seconds or minutes. If this type of low blood pressure occurs after eating, it is called postprandial orthostatic hypotension. This type most often affects older adults, those with high blood pressure, and people with Parkinson disease.

Neurally mediated hypotension (NMH) most often affects young adults and children. It can occur when a person has been standing for a long time. Children usually outgrow this type of hypotension.

Certain medicines and substances can lead to low blood pressure, including:

Alcohol
Anti-anxiety medicines
Certain antidepressants
Diuretics
Heart medicines, including those used to treat high blood pressure and coronary heart disease
Medicines used for surgery
Painkillers

Other causes of low blood pressure include:

Nerve damage from diabetes
Changes in heart rhythm (arrhythmias)
Not drinking enough fluids (dehydration)
Heart failure

Prevention

Your provider may recommend certain steps to prevent or reduce your symptoms including:

Drinking more fluids
Getting up slowly after sitting or lying down
Not drinking alcohol
Not standing for a long time (if you have NMH)
Using compression stockings so blood does not collect in the legs

 
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