Low blood pressure (hypotension) is a condition in which the force of blood pumping through the arteries is lower than normal.
There is no specific measurement at which blood pressure is considered too low. For some people, a low blood pressure is normal, and in general, lower blood pressure is better.
It is not always necessary to fix low blood pressure, especially if low blood pressure does not cause any bothersome symptoms. When symptoms of low blood pressure occur, treatment depends on the symptoms.
Lifestyle changes to fix low blood pressure may include:
- Drinking more fluids
- Changing how you sit and stand up
- Changing what and how you eat
- Compression stockings
Medical intervention to fix low blood pressure may include:
- Medication to raise blood pressure
- Adjusting medicines that cause low blood pressure (never change the dose or regimen of a prescribed medication without first talking to your doctor)
What Are Symptoms of Low Blood Pressure?
Chronically low blood pressure is usually only a medical concern if it causes symptoms such as:
- Lightheadedness
- Dizziness
- Fatigue
- Fainting
- Dehydration
- Nausea
- Unusual thirst
- Cold, clammy, pale skin
- Blurry vision
- Difficulty concentrating
- Depression
Extremely low blood pressure can lead to shock, which is a medical emergency. Call 911 and get to a hospital’s emergency department (do not attempt to drive yourself) if you notice signs of shock including:
- Weak and rapid pulse
- Rapid, shallow breathing
- Cold and sweaty skin
- Bluish skin tone
What Causes Low Blood Pressure?
Causes of low blood pressure include:
- Some medications
- Diuretics and other drugs used to treat high blood pressure
- Heart medications such as beta blockers
- Erectile dysfunction drugs (especially when combined with nitroglycerine)
- Parkinson's disease medications
- Tricyclic antidepressants
- Narcotics
- Alcohol
- Decreased blood volume, which can be caused by:
- Dehydration
- Major trauma
- Severe internal bleeding or anemia
- Prolonged bed rest
- Pregnancy
- Especially during the first 24 weeks blood pressure commonly drops
- Heart problems
- Abnormally low heart rate
- Heart attack
- Heart valve problems
- Heart failure
- Endocrine problems
- Low blood sugar and diabetes
- Underactive thyroid (hypothyroidism)
- Parathyroid disease
- Adrenal insufficiency (Addison’s disease)
- Autonomic nervous system disorders, such as Parkinson’s disease
- Severe infection (septic shock)
- Severe allergic reaction (anaphylaxis)
- Neurally mediated hypotension, a disorder that causes blood pressure to drop after standing for long periods
- Nutritional deficiencies, including low levels of vitamins B-12 and folic acid
- Older age
From 
Heart Health Resources
https://www.heart.org/en/health-topics/high-blood-pressure/the-facts-about-high-blood-pressure/low-blood-pressure-when-blood-pressure-is-too-low
https://www.nhlbi.nih.gov/health-topics/low-blood-pressure