9 Common Causes of Low Blood Pressure (Hypotension)

If you’re like 1 out of 3 Americans living with high blood pressure, then you and your doctor would probably be happy to see your blood pressure get lower. However, getting blood pressure too low can lead to plenty of problems, too.

What Causes Low Blood Pressure?

Doctors and researchers know that certain things can increase the chances of someone experiencing low blood pressure and it’s associated symptoms.

Let’s look at what these causes are…

1. Orthostatic Hypotension (Postural Hypotension)

Orthostatic hypotension is considered a main category of low blood pressure. It happens after a person gets up too quickly after they’ve been sitting or lying down. 

Why Does It Happen?

Blood tends to pool in our legs when we stand up, because the force of gravity starts to pull the blood down. But when our heart and blood vessels are working properly, we’re able to correct this effect of gravity and pump blood “up” toward our upper body and head.

If this upward pumping effect of blood isn’t working properly for some reason, then there won’t be enough blood reaching our upper body and head, and the blood pressure in our brain will suddenly drop. This process can lead to telltale symptoms like lightheadedness or fainting.

What Causes this Kind of Hypotension?

Orthostatic hypotension can be caused by a lot of things, including prolonged bedrest and dehydration (we’ll learn about dehydration and other low blood pressure causes in a moment). Before we go on, let’s review three other main category of low blood pressure that doctors often look at. These include:

Neurally Mediated Hypotension

This type of low blood pressure is caused by faulty signals between the brain and heart. It usually affects children and young adults, and causes a sudden drop in blood pressure after a person has been standing for a long time.

Postprandial Hypotension

Postprandial means “after eating.” Postprandial hypotension happens when blood pressure suddenly drops after a meal. This usually affects people with other underlying health conditions, like Parkinson’s disease or high blood pressure.

Postprandial hypotension happens if the systems in the body which help maintain blood pressure after eating stop working. These systems are important, because after you eat more blood gets sent to your digestive tract to help you digest food. This sudden redirection in blood flow can lead to blood pressure changes unless the body controls it. 

Multiple System Atrophy with Orthostatic Hypotension

This is a rare condition called Shy-Drager syndrome, and leads to low blood pressure due to progressive damage to parts of the nervous system that control blood pressure and other involuntary functions. It usually is associated with high blood pressure while lying down.

Other Symptoms of Orthostatic Hypotension

Orthostatic hypotension is one of the leading causes of low blood pressure, and its symptoms are almost the exact same. They include:

  • Lightheadedness and dizziness
  • Blurry vision or “seeing stars”
  • Weakness
  • Fainting (syncope)
  • Confusion or change in mental status
  • Nausea

With orthostatic hypotension, these symptoms develop after a person goes from lying down to sitting, or from sitting to standing.

2. Dehydration

Your body, organs, tissues, and even your blood is all made mostly of water. If you don’t replenish your body regularly with fluids, then your blood volume can start to decrease since there will be less water in it. This means your blood will take up less space and won’t be able to exert as much pressure against the blood vessel walls.

This explains why being dehydrated can lead to low blood pressure. 

Other Symptoms of Dehydration

Other symptoms of acute and chronic dehydration include:

  • Extreme thirst
  • Decreased urination
  • Dark-colored urine
  • Fatigue
  • Dizziness
  • Confusion
  • Dry mouth and tongue
  • Poor skin turgor (sometimes called skin “tenting,” which happens when you pinch the skin and the skin stays up in a tent rather than returning down to its normal flat position)
  • Fever 
  • Vomiting and nausea
  • Decreased sweat
  • Flushed skin

3. Medications

Some medications cause low blood pressure as an unexpected side effect. Certain people may be more at risk to experience this side effect depending on how they take the medication and if they have any other underlying health problems.

What Medications Cause Low Blood Pressure?

Common medications that can cause low blood pressure include:

  • Diuretics (Lasix/furosemide)
  • Heart medications like beta blockers
  • Certain types of antidepressants
  • Some drugs for Parkinson’s disease
  • Some drugs for erectile dysfunction

Seek Professional Help

Talk to your doctor about all the medications you’re taking and be sure you understand what the common side effects and adverse effects are. 

4. Heart Problems

Problems with the way a heart works can affect how blood is circulated throughout the body. In some cases, these problems can lead to low blood pressure.

What Heart Problems Lead to Low Blood Pressure?

  • Heart valve problems
  • Low heart rate (bradycardia)
  • Irregular heart rate (atrial fibrillation or a-fib)
  • Heart attack
  • Congestive heart failure

Other Symptoms of Heart Problems

Many types of heart problems exist. In addition to low blood pressure, other common signs and symptoms of a heart condition include:

  • Heart palpitations (feeling like the heart is fluttering or skipping a beat)
  • An usually fast or slow pulse
  • Chest pain or pressure
  • Shortness of breath
  • Easily fatigued or tired
  • Swelling in the arms and legs (edema)
  • Weakness
  • Dizziness

5. Endocrine Problems

The endocrine system is a large network of organs, tissues, hormones, and chemical messengers that influence many functions in the body.

What Conditions Lead to Low Blood Pressure?

Certain health conditions affecting the endocrine system and endocrine organs can lead to low blood pressure. These conditions may include:

  • Diabetes
  • Addison’s disease
  • Low blood sugar (hypoglycemia)
  • Parathyroid disease

Other Symptoms of Endocrine Problems

Symptoms of an endocrine problem can vary greatly depending on the part of the endocrine system that’s affected. Fatigue and weakness are common problems. 

6. Severe Infection or Allergic Reaction

An infection that gets into the bloodstream (sepsis) or a severe allergic reaction (anaphylaxis) can trigger a strong immune system and release toxins and other chemicals into the blood. Sometimes, this can cause the blood vessels to widen, which leads to a sudden drop in blood pressure.

These conditions can be life-threatening.  

Other Symptoms of Severe Infection or Allergic Reaction

In addition to possible low blood pressure, other signs and symptoms of a severe infection or severe allergic reaction include:

  • Trouble breathing
  • Swelling (especially in the throat and mouth with an allergic reaction)
  • Hives, rashes, and skin discoloration
  • Itching
  • Pain
  • Chills and fever
  • Low blood clotting factors
  • High white blood cells
  • Decreased urination

7. Severe Blood Loss or Trauma

Severe blood loss can occur on the inside of the body (such as a bleed in the digestive tract) or on outside the body (due to a severe wound or traumatic amputation). If the body loses enough blood, this will cause there not to be enough blood in the blood vessels, and the blood pressure will drop. 

Other Symptoms of Severe Blood Loss or Trauma

  • Visual injuries, such as broken bones, active bleeding
  • Unusual bruising, pain, or swelling
  • Decreased red blood cells (anemia)
  • Shock (confusion, cold clammy skin, weakness, rapid pulse)

8. Nutrient Deficiency or Insufficiency

Your body needs a variety of vitamins, minerals, and other nutrients in order to support normal function, tissue growth, and repair. For example, Vitamin B12, iron, and folate are important nutrients that help your body make red blood cells.

If you don’t have enough of these nutrients in your diet—or if your body can’t absorb these nutrients properly from the food you eat—your body may start to have to few red blood cells. The result? Anemia, which can sometimes lead to low blood pressure.

Other Symptoms of Nutrient Deficiency or Insufficiency

Other signs of vitamin B12 deficiency include:

  • Weakness and fatigue
  • Difficulty walking and keeping your balance
  • Tingling, numbness, and altered sensations in the hands and feet 
  • A swollen tongue
  • Memory loss, trouble thinking

Other signs of iron deficiency include:

  • Weakness
  • Pale skin
  • Brittle nails
  • Cold feet
  • Headaches
  • Lightheadedness and dizziness
  • Unusual cravings for non-food items like ice or starch
  • Inflamed sore tongue

Other signs of folate deficiency include:

  • Fatigue
  • Irritability
  • Shortness of breath
  • Swollen tongue and sores in the mouth
  • Pale skin

9. Pregnancy

When a woman becomes pregnant, her circulatory system will expand and grow in order to supply enough blood, oxygen, and nutrients to the growing baby and the placenta. Sometimes, this can lead to decreased blood pressure.

Preeclampsia is a complication of pregnancy associated with high blood pressure and liver and kidney damage. This is a potentially life-threatening condition for the mother and her baby, and requires close medical attention. 

Other Considerations for Pregnancy

If you’re pregnant, be sure to check in with your doctor or OB/GYN regularly and let them know about any unusual signs and symptoms you may have.

While research shows that it’s healthy and beneficial to exercise before, during, and after your pregnancy, you should also talk to your doctor about your exercise routine, adjust your activities to meet your ability and needs. Stop exercising if you notice any signs of intolerance or if you have any contraindications.

What’s Next?

What are the potential complications of low blood pressure that make this condition potentially dangerous?…

Is Low Blood Pressure Dangerous?

Some people have low blood pressure all the time without any symptoms or issues. But if a person’s blood pressure gets very low or drops too quickly, then a variety of complications can happen.

What are the Complications of Low Blood Pressure?

Some of these complications can be serious or even fatal. They can include:


Falls may lead to other injuries, such as:

  • Sprain
  • Strains
  • Cuts
  • Broken bones
  • Bleeding in the brain


Shock is a life-threatening condition caused by a lack of blood flow in the body. Signs and symptoms of shock include:

  • Sudden confusion
  • Pale and clammy skin
  • Rapid breathing
  • A weak and fast pulse

Organ Damage or Failure

Organ damage or organ failure can happen when organs and tissues stop getting enough blood delivered to them and become depleted of important nutrients and oxygen.

Other Unpleasant Symptoms

In addition to these complications, a person with too low blood pressure may exhibit a number of uncomfortable signs and symptoms, including weakness, dizziness, and fatigue. These signs and symptoms aren’t specific to low blood pressure and can happen because of other conditions, too. 

These signs and symptoms aren’t specific to low blood pressure and can happen because of other conditions, too. 

Given the potential complications of low blood pressure, it pays to know how to spot hypotension if you think you have it.

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