Why is My Blood Pressure Low?

Have you checked your blood pressure at home and found your blood pressure was low? A blood pressure reading that's lower than 90 mm Hg for the top number (systolic) or 60 mm Hg for the bottom number (diastolic) is generally considered low blood pressure. This article will discuss the possible cause of low blood pressure and what to do with it.

Low blood pressure can occur with:

  • Prolonged bed rest
  • Pregnancy: During the first 24 weeks of pregnancy, it’s common for blood pressure to drop.
  • Decreases in blood volume: A decrease in blood volume can also cause blood pressure to drop. A significant loss of blood from major trauma, dehydration or severe internal bleeding reduces blood volume, leading to a severe drop in blood pressure.
  • Certain medications: A number of drugs can cause low blood pressure, including diuretics and other drugs that treat hypertension; heart medications such as beta blockers; drugs for Parkinson’s disease; tricyclic antidepressants; erectile dysfunction drugs, particularly in combination with nitroglycerine; narcotics and alcohol. Other prescription and over-the-counter drugs may cause low blood pressure when taken in combination with high blood pressure medications.
  • Heart problems: Among the heart conditions that can lead to low blood pressure are an abnormally low heart rate (bradycardia), problems with heart valves, heart attack and heart failure. Your heart may not be able to circulate enough blood to meet your body’s needs.
  • Endocrine problems: Such problems include complications with hormone-producing glands in the body’s endocrine systems; specifically, an underactive thyroid (hypothyroidism), parathyroid disease, adrenal insufficiency (Addison’s disease), low blood sugar and, in some cases, diabetes.
  • Severe infection (septic shock): Septic shock can occur when bacteria leave the original site of an infection (most often in the lungs, abdomen or urinary tract) and enter the bloodstream. The bacteria then produce toxins that affect blood vessels, leading to a profound and life-threatening decline in blood pressure.
  • Allergic reaction (anaphylaxis): Anaphylactic shock is a sometimes-fatal allergic reaction that can occur in people who are highly sensitive to drugs such as penicillin, to certain foods such as peanuts or to bee or wasp stings. This type of shock is characterized by breathing problems, hives, itching, a swollen throat and a sudden, dramatic fall in blood pressure.
  • Neurally mediated hypotension: Unlike orthostatic hypotension, this disorder causes blood pressure to drop after standing for long periods, leading to symptoms such as dizziness, nausea and fainting. This condition primarily affects young people and occurs because of a miscommunication between the heart and the brain.
  • Nutritional deficiencies: A lack of the essential vitamins B-12 and folic acid can cause anemia, which in turn can lead to low blood pressure.
  • Measuring error: low blood pressure could also occur when the arm cuff is worn too loosely or in wrong position. If you have a lower-than-normal blood pressure reading, please make sure you wear the arm cuff correctly and check it again.

If you notice a sudden decline in blood pressure

A single lower-than-normal reading is not cause for alarm, unless you are experiencing any other symptoms or problems. If you experience any dizziness, lightheadedness, nausea or other symptoms, it’s a good idea to consult with your healthcare provider or call 911. To help with your diagnosis, keep a record of your symptoms and activities at the time they occurred.

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