men with low blood pressure is feeling very tired

The causes of low blood pressure span from heart conditions and dehydration to a lack of vitamins and anaemia.

Low blood pressure is often temporary and treatable, provided that you consult a doctor to find out the causes. A lot of the time, low blood pressure is not really a problem for people. It’s only when your blood pressure gets dangerously low that it becomes a threat to your health. You should therefore watch out for signs such as light-headedness, dizziness or fainting.

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What is low blood pressure?

A normal blood pressure is around 120/80 (120 over 80), however it's considered that someone has low blood pressure (also known as hypotension) when the blood pressure drops below 90/60 (90 over 60).

Low blood pressure means that the blood flow in the body might be insufficient to bring enough oxygen and nutrients to your organs. When blood pressure is extremely low, people can eventually lose consciousness.

People who suffer from a type of chronic low blood pressure (orthostatic hypotension) often experience problems when they get up from a lying or sitting position and feel lightheaded.

In more severe cases of low blood pressure, some people can suffer from different sorts of shocks, including strokes.

In itself low-ish blood pressure does not pose a direct threat to your health. There are people with blood pressure below 90/60 who lead perfectly normal lives. In the end, the presence of symptoms is what really determines whether you suffer from your low blood pressure or not. 

Causes of low blood pressure

There are a whole range of daily factors that can temporarily induce a low blood pressure such as stress, age, temperature, time of the day (e.g. evening) and time since the last meal. Also, staying in bed for a very long time causes a temporary drop in blood pressure.

These don’t make for huge differences in blood pressure but can explain why we feel dizzy or sleepy in such moments or when we make an effort (e.g. when getting out of bed).

When conditions and special circumstances (e.g accident) are involved, there are other possible causes of low blood pressure:

  • Pregnancy, especially during the first six months, when the body’s circulatory system is expanding and blood pressure isn’t adjusted yet;
  • Heart disease (e.g. a slow heart rate known as bradycardia) that lowers blood pressure, often because some malfunction in the heart causes it to pump not enough blood into the body – for example, after a heart attack;
  • Endocrine disorder, i.e. hormonal disease due to a gland malfunction (e.g. thyroid or kidneys) – in some cases diabetes can cause low blood pressure too;
  • Dehydration, most often caused by vomiting, diarrhoea, fever and heat strokes lead to huge loss of water. Mild dehydration may cause you to feel dizzy or even faint. If prolonged this can lead to shock and much more serious conditions;
  • Blood loss, due to an injury, internal bleeding or severe dehydration (less water in the blood) that result in a decrease in blood volume;
  • Septic shock, when a bacterial infection reaches the bloodstream from an infected organ;
  • Severe allergic reaction (breathing problems, hives, itching, swollen throat), usually resulting from certain foods, venomous insect sting or penicillin. This can cause a dangerous sudden drop in blood pressure;
  • Lack of essential vitamins in your diet will cause anaemia (not enough red blood cells) which is a direct cause of low blood pressure.

As you can see, the potential causes of low blood pressure are a long list of unrelated conditions, (in contrast to the causes of high blood pressure which are normally a mixture of lifestyle factors, family background and underlying conditions).

Medications can cause low blood pressure

Typically, medications for high blood pressure as well as for the heart and depression are potential causes of low blood pressure. That includes beta-blockers, alpha-blockers, calcium channel blockers along with tri-cyclical antidepressants.

In particular, if you take Viagra with a specific heart medication (nitroglycerine), this can cause a sudden drop in blood pressure.

You should also pay attention to water pills (diuretics) which make you visit the loo very often. This results in lower blood pressure by reducing the amount of water in your body.

Causes of low blood pressure in the elderly

It is common that as people grow old, the natural mechanisms for controlling the blood pressure via the heart rate (known as baroflex mechanisms) become less effective.

This is sometimes responsible for a decrease in blood pressure, particularly when elderly people stand up or get up after a long time in bed (true also for other people).

Is hypotension dangerous?

Hypotension (low blood pressure) is generally not a problem for your health. In fact, it provides protection against heart and kidney diseases as well as conditions related to high blood pressure such as heart attacks and strokes.

Low blood pressure is fine as long as it’s not excessively low so that you feel the symptoms, in which case there may be a risk of damage to your organs.

People who have so-called poor circulation symptoms (e.g. cold fingers and toes) probably have low blood pressure since it indicates that pressure is insufficient to send enough blood to distant parts of your body. However, these “poor circulation symptoms” are very common and you shouldn’t worry about them at all.

You should consult a doctor if you suffer from dizziness, fainting, serious dehydration (thirst) and excessively pale skin or fatigue.

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