High blood pressure is usually in the spotlight, but what about low blood pressure? It’s more common — and important — than you might think.

Here’s what you need to know about the causes of low blood pressure, and when you should do something about it.

Understanding what blood pressure means.

Like a garden hose that’s always on, blood is constantly moving through your arteries. Sometimes it’s a gentle flow, like when you’re reclining on the couch. That puts minimal pressure on your arteries. Sometimes it’s gushing, like when you’re at spin class and seriously get your heart pumping.

Here’s where blood pressure comes in.

“Blood pressure measures how hard your blood pushes against your artery walls,” says Christopher Firely, MD, a cardiologist at Hartford HealthCare Heart & Vascular Institute. “As the volume and force of blood flow increases, so does your blood pressure.”

> Related: What Your Blood Pressure Says About Your Health

How low is too low?

At any given time, your blood pressure reflects how hard your heart is working. This number is meant to vary throughout the day, within a certain range. The sweet spot for most adults is between 90/60 mmHg and 120/80 mmHg. Less than 90/60 mmHg is considered low.

Now, low blood pressure isn’t always a bad thing. But it’s worth keeping an eye on. It can be a clue that something else is going on with your health.

It can also cause symptoms like:

  • Dizziness
  • Fatigue
  • Fainting

“If not managed correctly, it can affect everything from your concentration and energy to your heart health,” says Dr. Firely.

> Related: 5 Signs You Have a Healthy Heart

6 common causes of low blood pressure

1. Genetics

Like other chronic conditions, low blood pressure can run in families.

“For some people, it’s just part of their biology,” Dr. Firely explains. “If you don’t have any symptoms and your doctor is in the loop, it’s usually nothing to worry about.”

2. Dehydration

Even mild dehydration can have a big impact on how blood flows through your body.

“Almost half of your blood is made up of water. So when you’re dehydrated — even mildly — the volume of blood flowing through your arteries goes down. That lowers your blood pressure,” says Dr. Firely.

Other signs of dehydration to watch for include dry mouth, dark urine and fatigue.

3. Standing up too quickly

Ever felt dizzy after standing up too fast? It was probably because of a change in your blood pressure.

“Sudden changes in position can cause a temporary drop in your blood pressure, a condition called orthostatic hypotension,” says Dr. Firely. “That can make you lightheaded or dizzy, or even cause fainting.”

4. Side effects of medication

Some medication — both prescription and over-the-counter — can impact your blood pressure.

“As a side effect, medications like pain relievers, antidepressants, and even some over-the-counter allergy meds can relax your blood vessels or reduce your blood volume, which lower your blood pressure,” says Dr. Firely.

5. Anemia

If your body doesn’t have enough healthy red blood cells or hemoglobin, it struggles to deliver oxygen, which can lower your blood pressure.

“When you’re anemic, your blood pressure may dip,” says Dr. Firely. “Often, the solution is as simple as getting more iron or vitamin B12. Your health team can advise you on the best way to address it.”

6. Another underlying condition

Occasionally, low blood pressure is a sign or symptom of a more serious issue.

“Sometimes, low blood pressure can be a sign of something serious like a heart condition, an underlying infection, an endocrine issue or even a neurological disorder like multiple sclerosis,” says Dr. Firely.

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When to see a doctor

Low blood pressure isn’t always a problem, but it’s a piece of the puzzle in understanding your overall health — and feeling your best.

“While low blood pressure is often manageable, it’s essential to get the right support if it’s affecting your quality of life,” says Dr. Firely. “Often, we can recommend simple lifestyle changes to help.”

Time to make low blood pressure a high priority.