Low blood pressure, or hypotension, is less common than high blood pressure, but for those affected low blood pressure is more likely to cause troublesome symptoms. Low blood pressure is diagnosed when your blood pressure falls below 90/60 mmHg. Just as a blood pressure that is too high can cause problems, so can a blood pressure that is too low.
Causes of low blood pressure
Low blood pressure can be caused by standing up too quickly, especially in older people, dehydration or even by eating a heavy meal which diverts blood towards the intestines to aid digestion.
Sudden severe low blood pressure can also result from medical causes such as loss of blood (haemorrhage), severe allergic reactions (anaphylaxis), infection (septic shock) and heart attack.
Symptoms of low blood pressure
The signs and symptoms of hypotension include feeling light-headed or dizzy, with cold, clammy skin, a dimming or blurring of vision, buzzing in the ears and even fainting.
The pulse becomes rapid and thready as the heart beats more quickly to deliver more blood around the body as it tries to compensate for the low blood pressure. However, if your pulse is both rapid and irregular, this is a sign of an abnormal heart rhythm such as atrial fibrillation.
NB If you have a rapid, irregular pulse you should see your doctor as soon as possible.
Other symptoms of low blood pressure are less obvious and non-specific such as tiredness, headaches, anxiety, depression and poor concentration which, together, are sometimes referred to as hypotension syndrome.
All of the symptoms of low blood pressure result from reduced blood flow to the brain. Low blood pressure means that brain cells do not receive all the oxygen and glucose they need to function properly. The severity of symptoms therefore depends on the suddenness and severity of the fall in blood pressure.
Blood pressure is naturally low in some people, and this is sometimes hereditary – for example, because your kidneys are particularly good at flushing excess sodium from your body.
If you don’t have symptoms, hypotension does not necessarily need treating. Some people develop persistent headaches, fatigue, anxiety, poor concentration, however, and cannot function properly at work or socially. This is known as hypotension syndrome and needs to be resolved so you can get on with a normal life.
Treatment of low blood pressure syndrome
If your doctor can find no underlying cause for your hypotension, the usual treatment approach is to suggest increasing your intake of dietary table salt (sodium chloride) and to avoid dehydration by drinking plenty of water (2 to 3 litres daily).
Avoid alcohol (which causes vasodilation, although in the long-term it can cause blood pressure to rise), avoid rigorous exercise, and try not to become over-heated, which also causes blood vessels to dilate so blood pressure falls further.
Elasticated compression stockings, socks or calve sleeves can also help by stopping blood from pooling in your legs under the effects of gravity.
Breathing exercise for low blood pressure
A pranayama breathing exercise known as Stage I viloma pranayama – meaning against the natural order – involves interrupted inhalation and is used to treat low blood pressure. This exercise is best performed lying down on your back, arms relaxed by your side in what is known as the Corpse Posture (Savasana).
The instructions on how to follow this natural remedy for low blood pressure are as follows:
Lie quietly with your eyes closed and rest for at least five minutes in quiet contemplation. When you feel ready:
- Breathe in for two to three seconds then pause, holding your breath for two to three seconds.
- Continue to breathe in for another two to three seconds before pausing again.
- Repeat this until your lungs are full (normally four to five pauses).
- Now breathe out slowly and steadily until your lungs feel empty.
Breathe normally before repeating the interrupted inhalation once more.
Supplements for low blood pressure
Korean ginseng or Guarana supplements can also help. If you are taking any prescribed medication, check with a pharmacist whether or not this is contributing to the your low blood pressure.
Korean ginseng for low blood pressure
Korean ginseng supplements, extracts from the roots of an Asian plant (Panax ginseng), are often recommended as a treatment for hypotension syndrome. Herbalists class Korean ginseng as an ‘adaptogen’ as it helps the body adapt to physical or emotional stress, reduces fatigue and has a normalising action on many body systems, including the circulation. Traditionally, ginseng is not usually taken for more than 6 weeks without a break.
Select products standardised to contain at least 4% to 8% ginsenosides. These will generally be more expensive, but cheap versions may contain very little active ingredient.
Guarana for low blood pressure
Caffeine is a stimulant, which helps to increase blood pressure by causing blood vessels to constrict. Drinking coffee is often recommended to treat low blood pressure. I prefer using Guarana, however, which is an extract from the seeds of a Brazilian rainforest shrub.
Guarana seeds have a rather alarming eyeball-like appearance as they burst from the fruit. Known in the Amazon as a ‘food of the gods’, dried guarana seeds contain a complex of natural stimulants, including caffeine (trimethyl xanthene), guaranine (tetramethyl xanthene), theobromine, theophylline and saponins similar to those found in Korean ginseng.
Guarana is an excellent natural source of caffeine as the saponins buffer its absorption to reduce the psychological over-stimulation and insomnia that can occur with caffeine.
Guarana is traditionally used to increase physical and mental energy levels, improve alertness and relieve fatigue.
NB Do not take any supplements if you are pregnant or if you are taking any other medications (check with a pharmacist for interactions first).
Low blood pressure and gravity
Gravity acts on blood in your circulation, drawing it downwards so that the average pressure in arteries below the level of your heart is higher than those above your heart.
When standing upright, for example, the average blood pressure (mid-point between your systolic and diastolic pressures) in arteries at the level of your heart is around 100 mmHg, while the average pressure in an artery in your foot is 180 mmHg average pressure but is just 62 mmHg for an artery in your head.
When you stand up suddenly from a lying position, the blood pressure falls in arteries taking blood to your brain. Blood also starts to pool in your lower leg veins so less is returned to your heart. Without a safety mechanism to prevent blood pressure collapsing, everyone would quickly faint on standing as blood flow to the brain would virtually cease. Instead, this sudden fall in blood pressure is detected by special cells (baroreceptors) in your heart and in your carotid arteries, which trigger several rapid reflexes. Your heart pumps more strongly, small arteries (arterioles) throughout the body constrict, blood vessels within the brain dilate, and circulating levels of certain hormones (renin and aldosterone) increase so that your blood pressure rises. Together, these rapid responses maintain blood pressure so that blood flow to the brain only decreases by less than 20% on standing, rather than the expected 60% or more which would make you black out.
As long as you keep moving while standing, the pumping action of muscles in your legs helps to keep blood flowing up from the lower half of your body back to your heart and then on to your brain. If you stand still for prolonged periods of time, however, such as when on guard duty, your blood pressure may slowly creep back down as blood pools in your leg veins due to the effects of gravity. Although you may feel embarrassed by fainting, it is an important, protective mechanism – by falling down, you lie flat so that blood flow to your brain is restored.
Treatment of low blood pressure on standing
Low blood pressure on standing is called postural hypotension or orthostatic hypotension. This occurs in some people when the protective reflexes that normally occur on standing do not respond as rapidly as usual. As a result, standing up quickly from a sitting or lying position causes a rapid drop in blood pressure. Systolic blood pressure (the upper reading) can fall by 20 mmHg or more.
Postural hypotension affects between one in ten and one in twenty people in their 60s, and becomes more common with increasing age. It can also occur in people taking medication to lower a high blood pressure – if this is the case, see your doctor as your medication or drug probably needs changing.
Low blood pressure after eating
Low blood pressure after eating is known as postprandial hypotension. When you eat a large meal, blood is diverted away from your muscles and general circulation towards your digestive tract to boost the absorption of nutrients from your food. In some people, this can cause blood pressure to fall by more than 20 mmHg within two hours of eating, leading to dizziness, light-headedness or falls. This form of low blood pressure is most likely in older people, and in those with diabetes or some neurological conditions such as Parkinson’s disease.
Treatment of low blood pressure after eating
If you have postprandial low blood pressure, it will help to eat little and often, and to avoid heavy meals. Limit your intake of stodgy foods such as white rice, pasta and bread so you only eat small amounts of low-carb foods. While white potatoes are a starchy food, there is some evidence that eating white potatoes can cause blood pressure to rise.
Some people may be advised to take a nonsteroidal anti-inflammatory drug (eg ibuprofen) before eating as these cause salt to be retained and increase blood volume; only do this if your doctor tells you to, as side effects can occur as well as interactions with other medications you may be taking.
Drinking coffee with meals may also help reduce low blood pressure after eating, as caffeine can cause blood vessels to constrict and prevent hypotension in some people. One study found that drinking two cups of coffee with a meal halved the incidence of postprandial hypotension but drink plenty of water to offset its diuretic effects.
Avoid caffeine with your evening meal if this will keep you awake, however.
Other causes of low blood pressure
There are other causes of low blood pressure, including pregnancy, hormone imbalances, heart problems and liver disease. A sudden catastrophic fall in blood pressure, with collapse, is known as clinical shock. This can be life threatening and can result from major blood loss, sepsis, heart attack or a severe allergic reaction to medication, bee venom or nuts, for example (anaphylactic shock).
If your blood pressure is low, self-monitoring is key to help prevent it going too low.
Click here for advice on choosing a blood pressure monitor to use at home.
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