Vasovagal syncope: causes, symptoms, treatment and what to do

Syncope (pronounced sin-co-pee) is a faint or short loss of consciousness, causing collapse with a natural recovery. Gloucestershire Hospitals NHS Foundation Trust says other terms include blackout or drop attack, and that syncope may be caused by a drop in blood pressure, a change in heart rhythm or breathing too quickly.

Vasovagal syncope, often called simple fainting, is a form of reflex syncope, also known as neurally mediated syncope. The Trust explains it is the result of changes in the nervous system causing a sudden drop in blood pressure and heart rate. This often happens when someone is standing up, can happen when sitting down, and rarely happens when lying down.

The Trust describes it as common and able to affect anyone, though it happens most often in young adults and is not often seen for the first time in older people. Injury to the person fainting does not often happen.

The Trust says that in most cases reflex syncope is not treated with medication. Management centres on recognising warning signs, acting early and avoiding triggers.

In certain situations medication can be used. The Trust says the medications most often used include fludrocortisone and midodrine, and that on rare occasions a permanent pacemaker is needed, which would be discussed in clinic. If you do not have high blood pressure, it says a 24 hour urine sample may measure how much sodium (salt) you pass, and if you are not eating enough salt you will be advised to eat more. Your GP may discuss treatment options if fainting becomes very regular.

The Trust says the exact cause is not fully understood, but it is often a temporary problem affecting the autonomic nervous system, the body's control system, so that blood pressure drops too low. Certain triggers affect the nerve messages that lower the heart rate and blood pressure.

The NHS lists causes of fainting in general that include standing up too quickly (which could be a sign of low blood pressure), not eating or drinking enough, being too hot, being very upset, angry or in severe pain, heart problems, and taking drugs or drinking too much alcohol. The Trust adds standing for a long time, the sight of blood, eating a large meal in a warm room, long haul flights, and actions such as coughing or passing urine.

• Standing still for a long time, for example in a queue.

• Long hot baths, overly warm places or heavy meals.

• Standing up too quickly.

• Not drinking enough, especially in hot weather.

• Severe pain, strong emotion or the sight of blood.

• Coughing or passing urine (reflex syncope).

The NHS says fainting usually happens suddenly, and symptoms can include dizziness, sweating, feeling warm or hot, feeling sick and changes to your vision. The Trust adds warning symptoms such as tiredness, weakness, loss of colour vision, tummy discomfort, headache, pins and needles, light-headedness or a spinning sensation. These may last seconds or minutes and are sometimes called presyncope. Older people may not have warning symptoms, and a faint can happen without warning.

After a collapse the person usually lies very still. The Trust says they may sometimes start to shake because less oxygen reaches the brain, which may be mistaken for epilepsy. As they come round they may feel sick, clammy, light-headed or tired, and some cannot stand for several minutes. Full recovery can take up to a few hours.

If you feel like you are about to faint, the NHS suggests you lie down with your legs raised, or if you cannot do that, sit with your head lowered between your knees, drink some water, cross your legs while standing up or rock up and down on your toes, and clench your fists. The Trust also suggests squatting if you cannot lie down, and squeezing firmly on a ball.

If you see someone faint, the NHS says to try to keep calm and check whether they respond by gently shaking their shoulders and asking loudly if they are OK. If they do not respond, shout for help and gently tilt back their head and lift their chin to help them breathe. Listen for breathing for at least 10 seconds. If they are breathing normally, lay them on their back and raise their legs. If they are pregnant, especially more than 28 weeks, the NHS says it is better to lay them on their side. Usually the person will wake up within 30 seconds.

The NHS says to see a GP if you have fainted, because it is important to get checked to find out what might have caused it. It says to call 999 if someone has any of the following, and not to drive yourself to A&E.

• Is not breathing.

• Cannot be woken up within 1 minute.

• Has not fully recovered or has difficulty with speech or movement.

• Has chest pain or a pounding, fluttering or irregular heartbeat.

• Has seriously hurt themselves before or after fainting.

• Is shaking or jerking (having a seizure or fit).

• Fainted while exercising.

• Fainted while lying down.

Fainting has many causes, and a GP will usually ask what happened and what you were doing and feeling before. The NHS says heart problems and low blood pressure when standing can also cause fainting, which is why it is worth being checked.

The NHS says you must tell the Driver and Vehicle Licensing Agency (DVLA) if you are fainting regularly, as it could affect your ability to drive, and that you must not drive if your GP has referred you to a specialist and you are waiting to be assessed.

GOV.UK says that for a car or motorcycle licence you should ask your doctor whether your blackouts, fainting or loss of consciousness affect your driving, and you must tell the DVLA if your condition affects your driving. For a bus, coach or lorry licence you must tell the DVLA if you have had a blackout, fainted or lost consciousness.

The Trust says that vasovagal syncope is not often seen for the first time in older people, and that older people may not have warning symptoms. If you are over 65 you may be referred to a falls clinic.

In pregnancy, the NHS says if you are with someone who has fainted and they are pregnant, especially more than 28 weeks, it is better to lay them on their side.

On the NHS a GP is the first step after a faint. They will ask about what happened and may arrange tests such as a heart tracing, and refer you to a specialist or a falls or syncope clinic if needed. If you are waiting to see a specialist you must not drive, according to the NHS.

Some people choose to see a private cardiologist for tests such as a heart tracing, longer monitoring or a tilt test, particularly after repeated faints. In general terms the questions are the same: whether a heart rhythm or blood pressure cause has been excluded, what triggers to avoid, and how the findings will be shared with your GP and, where relevant, the DVLA.