Low Blood Pressure – Symptoms and Causes

ByJanis Updated

Understanding Low Blood Pressure

Low blood pressure happens when the force of blood against artery walls is too low. Medical professionals refer to this condition as hypotension. A reading below 90/60 mm Hg is usually considered low blood pressure.

What counts as low blood pressure varies from person to person. Some people with low readings feel fine, while others may feel dizzy or even faint. In serious cases, low blood pressure can be dangerous.

Several things can cause low blood pressure, including not drinking enough water and certain health problems. Finding the cause is important for proper treatment.

Different Forms of Low Blood Pressure

Orthostatic hypotension occurs when blood pressure drops suddenly after standing up. This happens because blood temporarily pools in the legs instead of flowing back to the heart.

Common causes include:

  • Dehydration
  • Long periods of bed rest
  • Pregnancy
  • Certain medications
  • Various medical conditions

This type affects older adults most often.

Postprandial hypotension happens 1-2 hours after eating. Blood flows to the digestive system, causing a pressure drop elsewhere. It mainly affects:

  • Older adults
  • People with high blood pressure
  • Those with Parkinson’s disease
  • People with nervous system disorders

Eating smaller meals with fewer carbs, drinking more water, and avoiding alcohol can help manage symptoms.

Neurally mediated hypotension typically affects younger people, including children and teens. It happens after standing for a long time and may result from poor communication between the heart and brain.

Multiple system atrophy with orthostatic hypotension is a rare disorder affecting the autonomic nervous system (which controls automatic body functions). People with this condition often have very high blood pressure when lying down but dangerously low pressure when standing up.

Signs of Low Blood Pressure

Low blood pressure can cause various symptoms that range from mild to severe. People may experience blurry vision, dizziness, or feeling lightheaded. Some might faint or feel very tired. Others find it hard to focus or may have an upset stomach.

Sometimes, low blood pressure points to another health problem. This is especially true when blood pressure drops quickly or when symptoms appear alongside low blood pressure readings.

A sudden drop in blood pressure can be dangerous. Even a change of 20 mm Hg can make you dizzy or faint. For example, if your systolic pressure falls from 110 mm Hg to 90 mm Hg, you might feel unwell.

Large drops can be life-threatening and may happen due to:

  • Serious bleeding
  • Bad infections
  • Allergic reactions

Very low blood pressure can cause shock, which has these warning signs:

  • Confusion (especially in older adults)
  • Cold, clammy skin
  • Pale skin color
  • Fast, shallow breathing
  • Weak, rapid pulse

When to Get Medical Help

Call 911 right away if you have signs of extremely low blood pressure or shock. These are medical emergencies that need immediate care.

Healthcare providers usually only worry about low blood pressure when it causes symptoms. Brief dizzy spells can happen for many reasons, like being in hot weather or soaking in a hot tub too long.

It’s important to see a doctor to find the true cause of your symptoms. If your blood pressure readings are often low but you feel fine, you might not need treatment. Your doctor will likely monitor your health during regular checkups.

Keep track of your symptoms, when they happen, and what you’re doing at the time. This information helps your doctor understand your condition better.

What Causes Low Blood Pressure

Several health conditions can cause your blood pressure to drop below normal levels:

  • Pregnancy – During the first 24 weeks of pregnancy, blood vessels expand quickly, which often causes blood pressure to fall. Blood pressure typically returns to pre-pregnancy levels after giving birth.
  • Heart Problems – Several heart-related issues can lead to low blood pressure:
    • Heart attacks
    • Heart failure
    • Valve diseases
    • Slow heart rate (bradycardia)
  • Hormone Disorders – When the body’s hormone-producing glands don’t work properly, blood pressure may drop. Examples include:
    • Addison’s disease
    • Low blood sugar (hypoglycemia)
    • Diabetes
  • Dehydration – Not having enough water in your body reduces blood volume and can lower blood pressure. This might happen due to:
    • Fever
    • Vomiting
    • Severe diarrhea
    • Overuse of water pills
    • Heavy exercise
  • Blood Loss – Losing a significant amount of blood reduces the volume in your blood vessels, causing pressure to drop. This can happen from:
    • Injuries
    • Internal bleeding
  • Severe Infection – When infection enters the bloodstream (septicemia), it can cause a dangerous drop in blood pressure called septic shock.
  • Severe Allergic Reactions – During anaphylaxis, blood pressure can drop suddenly and severely.
  • Nutritional Deficiencies – Low levels of vitamin B-12, folate, or iron can lead to anemia (not enough red blood cells), which may cause low blood pressure.

Medications That May Lower Blood Pressure

Many medications can cause your blood pressure to drop, including:

Medication Type Examples Used For
Blood Pressure Medicines Diuretics (Lasix, Microzide)
Alpha blockers (Minipress)
Beta blockers (Tenormin, Inderal)		 Treating high blood pressure
Parkinson’s Disease Drugs Pramipexole (Mirapex ER)
Levodopa medications		 Managing Parkinson’s symptoms
Certain Antidepressants Tricyclic types like doxepin (Silenor)
Imipramine (Tofranil)		 Treating depression
Erectile Dysfunction Medications Sildenafil (Viagra)
Tadalafil (Adcirca)		 Especially dangerous when taken with nitroglycerin

Blood pressure naturally changes throughout the day based on:

  • Your body position
  • Breathing patterns
  • Food and drink intake
  • Medication timing
  • Physical condition
  • Stress levels
  • Time of day

Blood pressure is typically lowest while sleeping and rises quickly upon waking.

Normal healthy blood pressure is generally below 120/80 mm Hg, with the top number (systolic) showing pressure during heartbeats and the bottom number (diastolic) showing pressure between beats.

Risk Factors

Low blood pressure can affect people of all ages. Several factors increase your chance of developing this condition:

  • Age: People over 65 are more likely to experience drops in blood pressure when standing up or after eating. Younger individuals and children tend to develop neurally mediated hypotension more often.

  • Medications: Many drugs can lower blood pressure, especially those prescribed to treat high blood pressure.

  • Health Conditions: Several diseases might cause low blood pressure, including:

    • Parkinson’s disease
    • Diabetes
    • Certain heart problems

  • Substances: Consuming alcohol or illegal drugs may increase your risk of developing low blood pressure.

Complications

Low blood pressure can cause several problems, including dizziness, weakness, fainting spells, and falls with related injuries.

Dangerously low blood pressure can also prevent your body’s organs from getting enough oxygen. As a result, this can damage important organs like your heart and brain.


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Health Writer

Janis's areas of expertise include nutrition, exercise, stress management, and mental health. She is passionate about educating and empowering people to take control of their health and make positive changes that can last a lifetime. Janis believes that small, sustainable changes are the key to long-term success, and she works with her clients to develop personalized plans that fit their individual needs and lifestyles.