What low blood pressure means and when it can be dangerous

• Low blood pressure is defined by a blood pressure reading of 90/60 mm Hg or lower.
• Low blood pressure with no symptoms is rarely a cause for concern.
• If you also experience dizziness, shortness of breath, or fainting, seek medical attention.

Blood pressure is a measure of the force of blood moving through your artery walls. When that force is too low, your vital organs may not be getting the right amount of blood flow they need to function.

Here's what you need to know about what might cause low blood pressure and when it is considered an emergency.

What low blood pressure means

Hypotension is the medical term for low blood pressure, which is typically defined by a blood pressure reading of 90/60 mm Hg or lower. For reference, a normal blood pressure range is around 100/60 mm Hg to 120/80 mm Hg.

Low blood pressure with no symptoms is rarely a cause for concern, says Nicole Weinberg, MD, a cardiologist at Providence Saint John's Health Center. In fact, some people have chronic low blood pressure, but feel fine, and do not need to be treated.

However, if low blood pressure is combined with symptoms of dizziness, fainting, shortness of breath, or lightheadedness, it could be a sign that you need medical attention.

What causes low blood pressure

The exact cause of low blood pressure is not always clear, Weinberg says, but some common causes include:

• Side effects from over-the-counter or prescription medications, including drugs used to treat high blood pressure, like diuretics, as well as tricyclic antidepressants and erectile dysfunction drugs
• Pregnancy (often in the first 24 weeks), due to hormonal changes and expansion of the circulatory system
• Other hormone changes, including issues with the hormone-producing glands in the endocrine system
• Dehydration, heat exhaustion, or heat stroke

In addition, postural or orthostatic hypotension can occur when you quickly rise from a sitting or lying down position, causing a sudden drop in blood pressure and feelings of lightheadedness. This can last for just a few minutes or it can be more severe and cause fainting.

In fact, Parkinson's disease can impair the body's ability to automatically adjust blood pressure when changing positions, resulting in bouts of orthostatic hypotension. About one in five people with Parkinson's are affected by orthostatic hypotension.

Weinberg says orthostatic hypotension usually isn't a medical emergency unless it persists and you consistently feel lightheaded when you stand.

For someone experiencing an isolated episode of hypotension, Weinberg advises lying down, eating a salty snack, and drinking water — since fluids increase blood volume and can help get your blood pressure back to normal.

When low blood pressure is an emergency

If you frequently experience symptoms of low blood pressure, such as dizziness or fainting spells, you should consult a doctor. While low blood pressure, itself, usually isn't fatal, there are serious medical situations where it is considered an emergency, and you should go to the hospital.

"The likelihood of dying from low blood pressure is low unless it is related to another disease process," Weinberg says.

For example, a blood infection, or sepsis, can result in low blood pressure. Sepsis occurs when the chemicals released by the body to fight an infection trigger widespread inflammation, resulting in blood clotting that reduces blood flow to vital organs, such as your heart, kidneys, and brain. This can progress to septic shock and very low blood pressure, which may be fatal, and should be treated immediately.

Low blood pressure can also be affiliated with Addison's disease — a disorder in which the adrenal glands do not produce enough cortisol, a hormone that helps your body respond to stress. Lack of cortisol production can cause addisonian crisis, which is characterized by low blood pressure and can be fatal without proper treatment.

The treatment for low blood pressure varies depending on the cause. In severe cases, someone might need intravenous therapy (IV) to deliver fluids into the veins and raise blood pressure. In critical situations, such as septic shock, doctors may use drug therapies either orally or through an IV to quickly raise blood pressure.

Insider's takeaway

Low blood pressure, or hypotension, is often not a cause for concern. However, if it accompanies symptoms like fainting, shortness of breath, lightheadedness, or dizziness, you may need medical attention.

Some common causes of low blood pressure include pregnancy, hormonal changes, dehydration, and medication side effects.

Low blood pressure alone is not considered fatal, but there are some conditions where it's an emergency. Low blood pressure caused by Sepsis or Addison's disease calls for immediate medical treatment.