For most people, controlling their blood pressure means keeping it from getting too high. However, blood pressure that's too low — called hypotension — can also be a problem, especially in your senior years.

Blood pressure is the force of blood against your artery walls, explains the National Heart, Lung, and Blood Institute. It's measured in millimeters of mercury (mm Hg). A healthy blood pressure is a reading below 120/80 mm Hg. It's considered low at 90/60 or below. But how low is too low?

According to the American Heart Association (AHA), there's no number that's considered too low if you're in otherwise good health. However, the AHA also points out that low blood pressure could be a warning sign of an underlying health problem. One clue can be the low blood pressure symptoms you may be experiencing, such as dizziness, tiredness, nausea or fainting. Here's what else you need to know about hypotension.

As a result, older adults sometimes cannot readily respond to a dip in blood pressure, especially if they have high blood pressure, according to Harvard Health Publishing. But there could be other specific causes for hypotension:

Medications

Some prescription and over-the-counter drugs can result in low blood pressure. Common offenders are medicines that treat high blood pressure, including calcium channel blockers, alpha blockers, beta blockers, ACE inhibitors, angiotensin II receptor blockers and diuretics. That's one reason your doctor will continually monitor your reaction to these drugs and tweak dosages as needed. Other culprits are narcotic pain medications, antidepressants and drugs for Parkinson's disease and erectile dysfunction, according to the Mayo Clinic.  

Heart conditions

Although your blood pressure and your heart rate are two distinct body functions, an extremely low heart rate — a condition called bradycardia — can cause hypotension, according to the Mayo Clinic. So can other changes in heart rhythm, heart valve problems, having a heart attack or having heart failure. Heart failure doesn't mean that your heart has completely failed to work. Rather, it means it's not pumping as well as it should. It may not be able to keep pressure in your arteries at an adequate level, resulting in low blood pressure and other problems, according to the National Library of Medicine.  

Endocrine system conditions

These include problems with glands that produce important hormones, like your thyroid. An underactive thyroid gland, as well as overactive parathyroid glands, can lower blood pressure, according to the Mayo Clinic. So can having low blood sugar. This is especially dangerous in older people with diabetes. When blood sugar drops too low, your heart works harder and your blood pressure falls. Nerve damage from long-standing diabetes can also be a contributing factor.  

A severe shock to your system

A serious accident with excessive blood loss or internal bleeding can lead to low blood pressure. So can a severe infection, like septic shock. That can be caused by an overload of bacteria in your blood that starts a life-threatening chain reaction, including a drop in blood pressure. Anaphylaxis, the most extreme type of allergic reaction, not only causes your throat to close but can also cause blood pressure to plummet.  

Vitamin deficiencies

Not getting enough vitamin B12 and folate (B9) can lead to anemia and, in turn, low blood pressure, according to the Mayo Clinic. Also, with advancing age, the body isn't always able to use the B12 in the foods you eat. Ask your doctor about checking your blood level even if you don't have signs of anemia.  

Dehydration

Your body can start losing water long before you actually feel thirsty. This can happen on a very hot day, after strenuous exercise or simply when you forget to take in enough liquids. Because it diminishes blood volume, dehydration can cause your blood pressure to fall, as well as causing symptoms such as dizziness and nausea.

 

A sudden change in position

If you've ever spent a lot of time in bed recuperating from an illness, you know that you can feel dizzy when first getting up. This is usually a sign of temporarily low blood pressure. Some people have dips in blood pressure when changing from lying or sitting to standing — the body just isn't as quick as it used to be in circulating your blood, according to the Mayo Clinic.  

More common among people over 65, these dips may last only minutes but can cause you to feel dizzy. This can also occur when you stand up after eating if your body can't balance blood flow during digestion as efficiently as it used to. According to Harvard Health Publishing, this is called post-prandial hypotension. It's more likely in people with high blood pressure or Parkinson's disease, which affects nerves involved in controlling blood pressure.

• Monitor your blood pressure

• Drink more water

• Be vitamin savvy

• Talk to your doctor about salt

When low blood pressure comes with a symptom like dizziness or feeling light-headed, you could be at risk for a serious fall. "If you find that you often feel like you're going to swoon when standing up, call your doctor," says Dr. Osborne.

Have your blood pressure taken when lying down, sitting up and standing to look for any changes. The answer may be as simple as taking more time when getting up. Also review all your medications to see if any adjustments need to be made. Your doctor might also want to test you for possible underlying medical conditions.

Some low blood pressure symptoms are more worrisome. "If you faint, lose consciousness, aren't able to concentrate, have vision changes like blurry vision or the loss of peripheral vision, or are very flushed, call 9-1-1," says Dr. Osborne.

Fainting is one of the most common reasons older people go to the emergency room, according to an April 2017 report in the Journal of Emergency Medicine. Tests and treatment will depend on your specific situation, but you'll most likely have an examination, an ECG (an electrocardiogram, a non-invasive test that measures your heart rate) and a review of your personal medical history.