Low Blood Pressure - Why is Your Blood Pressure Low?

Why is your blood pressure low?

As a doctor with an interest in the subject, I'm often asked if a low blood pressure is normal or if such a reading indicates some abnormal process in the body? In fact - it can be difficult to precisely define what we mean by low blood pressure. It all really depends on what's normal for you as an individual.

If 1000 people had their blood pressure measured then we might expect to find a spread of readings. These might range from as high as 200 / 120 down to 80 / 50 with most people clustering around a level of around 130 / 85. Most of these people would have no symptoms of any kind - no matter what their blood pressure reading actually was. Even those with obviously low blood pressure would be free of any symptoms in most cases.

The answer to whether it is normal or abnormal to have a low blood pressure depends on what your own typical or average blood pressure reading is.

Here's an example of when it's normal to have low blood pressure.

If, for the whole of your life, you've always had blood pressure readings of around 90 / 50 - then without doubt you have "low blood pressure" but there is truly nothing wrong with you or with your blood pressure reading. You should be pleased that your risk of stroke or heart attack will be much less than many others. You're not likely to experience any symptoms from your "low blood pressure." Putting it simply - your blood pressure is normal for you and needs no investigation or treatment. This kind of "normal low blood pressure" will not cause you any symptoms and will need no treatment. It's just part of you and how your system works.

So, when might low blood pressure be an abnormal finding?

If your blood pressure is usually around 130 / 80 and suddenly or gradually drops to a level around 90 / 50 then it's very likely that you'll become aware of symptoms related to this change. As in the above example you have "low blood pressure" but in this instance it is not normal for you to have readings this low. You may need to see your doctor for tests because it's quite likely that some other disease or perhaps a medication has caused your blood pressure to drop. Someone who develops low blood pressure like this will often experience symptoms such as those listed below.

The symptoms of an abnormally low blood pressure can include:

Feeling light headed, feeling dizzy, being tired or feeling fatigue on exertion, fainting, transient blurring of vision, or transient confusion. All of these low blood pressure symptoms will resolve if the blood pressure returns to normal.

The following are among the many possible causes of low blood pressure when it is abnormally low:

Medications for anxiety, medications for blood pressure, heart medications, diuretics or "water tablets" and some anti-depressant medications. Other medication related causes are painkillers and alcohol - particularly if these two are mixed together!

Non medication causes of include dehydration, heart disease and heart valve disease, recent heart attack, changes in heart rhythm, bacterial infection in the system, kidney diseases, diabetes mellitus and haemorrhage or bleeding.

As you can see, the above list of the causes of low blood pressure is extensive and you should consult with your doctor if you are concerned in any way. Above all - don't try to diagnose your own condition - seek help if you are worried. Low blood pressure is not likely to do you any serious harm but it can leave you feeling pretty miserable.

Gordon Cameron MD is based in Edinburgh, Scotland. He has a special interest in blood pressure problems in general and in low blood pressure in particular.

Follow these links to his website for more information about low blood pressure or about high blood pressure treatment.