Low Blood Pressure - When Blood Pressure Is Too Low

How low is too low for blood pressure?

A low blood pressure reading is usually good. Some people with very low blood pressure have a condition called hypotension. This occurs when blood pressure is less than 90/60 mm Hg. Low blood pressure is usually not harmful unless there are other symptoms that concern a health care professional.

Symptoms of low blood pressure

Constantly low blood pressure can be dangerous if it causes signs and symptoms such as:

  • Confusion
  • Dizziness
  • Nausea
  • Fainting
  • Fatigue
  • Neck or back pain
  • Headache
  • Blurred vision
  • Heart palpitations, or feelings that your heart is skipping a beat, fluttering or beating too hard or too fast

Underlying causes of low blood pressure

Low blood pressure can happen with:

  • Prolonged bed rest
  • Prolonged standing
  • Depression
  • Parkinson’s disease
  • Pregnancy
  • Dehydration
  • Certain medications and substances can cause low blood pressure including:
    • Diuretics and other drugs that treat high blood pressure
    • Heart medications such as beta blockers
    • Drugs for Parkinson’s disease
    • Tricyclic antidepressants
    • Erectile dysfunction drugs, particularly in combination with nitroglycerine
    • Narcotics
  • Heart problems: Heart conditions that can lead to low blood pressure are:
  • Endocrine problems:
    • Underactive thyroid
    • Addison’s disease
    • Low blood sugar
    • Diabetes
  • Nutritional deficiencies: A lack of the essential vitamins B-12 and folic acid can cause anemia, a lower-than-normal amount of healthy red blood cells. This can lead to low blood pressure.
  • Life-threatening scenarios
    • Septic shock: This can occur when bacteria from an infection enter the bloodstream. The bacteria then produce toxins that affect the blood vessels. This can lead to dangerously low blood pressure.
    • Allergic reaction: Anaphylactic shock is an allergic reaction that can lead to death. It can happen in people who are highly sensitive to drugs such as penicillin. It also can happen after eating certain foods or being stung by a bee or wasp.
    • Decreases in blood volume: A significant loss of blood from major trauma or severe internal bleeding reduces blood volume. This can lead to a severe drop in blood pressure.

If you notice a sudden decline in blood pressure

One reading that is lower than normal is usually not cause for alarm unless you are having other symptoms or problems. If you are dizzy, nauseous or have other symptoms, contact your health care professional. Keep a record of your symptoms and when they happened. Is low blood pressure related to low heart rate? Find out.

Written by American Heart Association editorial staff and reviewed by science and medicine advisors.

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Last Reviewed: May 6, 2024