Kate Halim
Low blood pressure might seem desirable, and for some people, it causes no problems. However, for many people, abnormally low blood pressure also known as hypotension can cause dizziness and fainting. In severe cases, low blood pressure can be life-threatening.
A blood pressure reading lower than 90 millimeters of mercury (mm Hg) for the top number (systolic) or 60 mm Hg for the bottom number (diastolic) is generally considered low blood pressure.
The causes of low blood pressure can range from dehydration to serious medical disorders. It’s important to find out what’s causing your low blood pressure so that it can be treated.
Unlike high blood pressure, doctors usually don’t use a standard set of numbers to figure out if you are ill. But if you also have symptoms like dizziness and nausea, it could be a sign that your blood pressure is too low for good health.
Measuring blood pressure
A cuff linked to a special device tightens around your arm to get two measurements. The top number, or systolic, notes the pressure your blood makes against your artery walls when the heart beats. The bottom number, or diastolic, measures the pressure between beats, while the heart is relaxing and filling with blood. You can get readings in your doctor’s office or at home.
Symptoms
Your brain usually shows the first symptoms of hypotension. Besides dizziness and nausea, your spirits might be low; you might lack energy, and find it hard to think straight.
Some people feel lightheaded enough to faint or notice cold, clammy skin, faster breathing, blurry vision, or chest pain. If your low pressure is caused by dehydration, you also might feel unusually thirsty.
Risk factors
Low blood pressure (hypotension) can occur in anyone, though certain types of low blood pressure are more common depending on your age or other factors:
Age
Drops in blood pressure on standing or after eating occur primarily in adults older than 65. Neurally mediated hypotension primarily affects children and younger adults.
Medications
People who take certain medications, for example, high blood pressure medications such as alpha blockers, have a greater risk of low blood pressure.
Certain diseases
Parkinson’s disease, diabetes and some heart conditions put you at a greater risk of developing low blood pressure.
Causes of low blood pressure
Expanded blood vessels
Sometimes your blood vessels widen. That means there’s more space for blood to spread out, which puts less pressure on the walls of those vessels. Some drugs, especially a type called vasodilators, can cause this. So can spinal injuries that damage certain nerves, serious bacterial infections, and allergic reactions. Hormone problems like Addison’s disease, which weakens the adrenal glands, can also do it.
Less blood
Less blood means less pressure on your veins and arteries. Losing a lot of blood from a major injury or internal bleeding reduces the amount of blood in your body, leading to a severe drop in blood pressure.
It might also happen if you don’t get enough to drink, your blood vessels leak fluid, or you have a blood condition called anemia. Sometimes your kidneys get rid of too much fluid because of illness or certain drugs, like diuretics.
Pregnancy
Because the circulatory system expands rapidly during pregnancy, blood pressure is likely to drop. This is normal, and blood pressure usually returns to your pre-pregnancy level after you have given birth.
Heart problems
The more blood your heart pumps per minute, the higher your blood pressure. Certain medications, along with hormone problems, heart damage can make your heart beat too slowly, which lowers your blood pressure. It could also be that your heart is not as strong as it used to be because of a heart attack, heart failure, or problems with the valves, and doesn’t pump as much blood per beat.
Dehydration
When your body loses more water than it takes in, it can cause weakness, dizziness and fatigue. Fever, vomiting, severe diarrhea, overuse of diuretics and strenuous exercise can lead to dehydration. And dehydration can be a sign of low blood pressure.
Standing quickly
Normally when you stand suddenly, your body sends a signal to your brain to pump more blood to your brain. But sometimes, your brain doesn’t get the message quickly enough and you start to feel lightheaded. You might even faint.
Lack of nutrients in your diet
A lack of the vitamins B-12 and folate can keep your body from producing enough red blood cells (anemia), causing low blood pressure.
Standing for long periods
After you are on your feet for a while, blood can start to pool in your legs. If your brain doesn’t tell your heart to pump enough to keep your blood pressure up, it might drop low enough to make you dizzy and nauseous.
You might even pass out. Your doctor might call this neurally mediated hypotension. Like a bad relationship, the problem is poor communication, in this case, between the heart and brain.
Getting a diagnosis
Once your doctor knows your symptoms, blood tests can help diagnose the reason for your low blood pressure. An electrocardiogram, ultrasound, and other tests check your heart health.
The Valsalva maneuver observes nerve signals that control your heart and blood vessels, and a tilt table test looks at how your body responds to position changes.
Treatment
It depends on the cause. You may need to the treat the conditions that are giving you low blood pressure. If medication is the problem, you may need to change it or lower the dose, but always talk to your doctor first.
Other drugs can help lower your pressure, and compression socks can help push blood up from where it pools in your legs. If you don’t have bothersome symptoms, you might not need treatment.
Lifestyle changes
You can help lessen the symptoms of low blood pressure at home by adding more salt into your diet, but check with your doctor first.
You can improve your blood pressure by drinking more water. It keeps your blood volume up, which raises blood pressure.
Also, you can cut back on alcohol. It can dehydrate you and lower blood volume and blood pressure.
Eat multiple, small meals that are low-carbohydrates instead of three big ones, if your pressure drops after eating.
When to see a doctor
If you feel confused or notice fast, shallow breathing, a weak, rapid pulse, and cold, clammy skin, you may be in shock which is also known as extreme hypotension. Get to the hospital immediately.
But lower blood pressure numbers, especially without other symptoms, aren’t usually a sign of a big problem. Talk to your doctor if you start to feel dizzy or lightheaded as well.