Hy­po­ten­sion / Low blood pres­sure

Low blood pressure may be a sign for an underlying problem, especially when it drops suddenly or when it’s accompanied by any of the following symptoms:

• Dizziness
• Fatigue
• Thirst
• Fainting
• Poor concentration
• Blurry vision
• Confusion
• Weakness
• Nausea
• Cold, pale skin
• Rapid, shallow breathing
• Depression

Depending on the causes, physicians distinguish different types of low blood pressure, such as:
 

• Orthostatic or postural  hypotension – a sudden drop in blood pressure when a person stands up from a sitting position or after lying down. Orthostatic hypotension may occur due to dehydration, prolonged bed rest, diabetes, burns, excessive heat, pregnancy, heart problems, burns, large varicose veins and neurological disorders. The condition is particularly common in older adults. Younger, healthy people may experience orthostatic hypotension after sitting with their legs crossed for a long time or after working for a while in a squatting position.
• Postprandial hypotension – a sudden drop in blood pressure after eating. Mostly older adults are affected by this condition, especially those with high blood pressure or autonomic nervous system disorders, e.g. Parkinson's disease.
• Neurally mediated hypotension – a drop in blood pressure after standing for a long time. The condition results in signs such as dizziness, nausea and fainting. It mostly affects young people. The cause might be a miscommunication between the heart and the brain.
• Multiple system atrophy with orthostatic hypotension (Shy-Drager syndrome) – This rare condition leads to progressive damage to the autonomic nervous system, which controls involuntary functions, e.g. blood pressure. The characteristic feature of shy-drager syndrome is severe orthostatic hypotension in combination with very high blood pressure when lying down.
   

Medical conditions that may cause low blood pressure:
 

• Pregnancy
  The circulatory system expands rapidly during pregnancy, and blood pressure might drop.
• Heart problems
  Very low heart rate, heart valve problems, heart attack and heart failure might result in low blood pressure.
• Endocrine disorders
  Parathyroid disease, low blood sugar and sometimes diabetes may trigger low blood pressure.
• Dehydration
  Fever, vomiting, severe diarrhea, overuse of diuretics and strenuous exercise can lead to dehydration. However, hypovolemic shock is a life-threatening complication of dehydration. A sudden drop in blood pressure and a reduction in the amount of oxygen reaching the tissues might cause death within a few minutes or hours.
• Blood loss
  Blood loss after a major injury or internal bleeding may result in a severe drop in blood pressure.
• Severe infection
  If an infection enters the bloodstream, it may cause a life-threatening drop in blood pressure (septic shock).
• Severe allergic reaction
  Certain foods, medications, insect venoms, etc. can result in a life-threatening allergic reaction with breathing problems, itching, swollen throat and a drop in blood pressure.
• Lack of vitamins B-12 and folate
  Blood pressure may drop if the body does not produce enough red blood cells.
   

Medications that may cause low blood pressure, e.g.:
 

• Diuretics (water pills)
• Alpha and beta blockers
• Some drugs for Parkinson's disease
• Some antidepressants
• Viagra

There is always a risk of injury, if a person passes out and falls to the ground. In patients with severely low blood pressure, the condition may deprive their body of enough oxygen to carry out its normal functions, resulting in damage to heart and brain.