The Role of Fluids to prevent Fainting

26th December 2022 | Dr Boon Lim & Philip Eardley


Vasovagal syncope and orthostatic intolerance are conditions characterized by abnormal autonomic responses that can lead to symptoms such as dizziness, lightheadedness, and fainting. Proper hydration plays a vital role in managing these conditions and alleviating symptoms. This article explores the benefits of fluids, including the consumption of cold fluids and front-loading hydration in the morning, as part of the treatment approach for individuals with vasovagal syncope and orthostatic intolerance.

The Importance of Hydration

Maintaining adequate hydration is essential for the proper functioning of the cardiovascular system and the regulation of blood pressure. In the context of vasovagal syncope and orthostatic intolerance, dehydration can exacerbate symptoms and increase the risk of fainting episodes. Here are key considerations regarding fluid intake:

Fluid Volume

Increasing fluid intake helps to expand blood volume, which can improve blood pressure regulation and enhance overall cardiovascular stability. Consuming an adequate amount of fluids throughout the day is crucial to prevent dehydration and its associated symptoms. Typically, for an average sized adult, we would recommend at least 2.5L a day, but do aim to consume more to replenish fluid loss during exercise, and during hot weather, particularly if you are losing a lot of fluid through sweating.

What about coffee and tea? and alcohol?

Coffee and tea should be limited to 1-2 cups a day for most patients who have frequent symptoms of fainting. This is because both coffee and tea are weak diuretic agents, which means that they can actually lead to production of more urine. In addition, the caffeine content in coffee and tea can make smyptoms worse in some patients. 

Alcohol should be avoided by most patients who have frequent episodes of fainting. This is because alcohol is a vasodilator, and can cause flushing in the blood vessels in the skin and gut which leads  to a further reduction in blood pressure, and trigger a fainting episode. Of course, this does not mean that you will never ever be able to drink again! If you need to enjoy alcohol on occasions, remember to chase down each unit of alcohol with ideally a pint of water to minimize the chance of a faint.

Cold Fluids

Vasoconstriction: Drinking cold fluids can stimulate vasoconstriction, causing blood vessels to narrow. This vasoconstrictive response helps to maintain blood pressure by increasing peripheral resistance, reducing the likelihood of orthostatic hypotension (a drop in blood pressure upon standing).

Enhanced Alertness: Cold fluids can provide a refreshing sensation and promote increased alertness, which may help counteract symptoms of dizziness and fatigue associated with orthostatic intolerance.

Front-Loading Hydration

Morning Hydration: Front-loading hydration involves consuming a significant portion of fluids in the morning, preferably soon after waking up. This approach aims to boost blood volume early in the day, when symptoms tend to be more pronounced, and can enhance orthostatic tolerance throughout the day. Manypatients are the most dehydrated on waking, because typically, they would not have drunk any fluids overnight, and would still have been producing urine and sweating under the duvet/sheets, and therefore be fluid depleted. This can explain why some patients experience their worst symptoms first thing in the morning.

Enhanced Hydration Status: By starting the day with adequate fluid intake, individuals with vasovagal syncope and orthostatic intolerance can optimize their hydration status and minimize the risk of symptoms triggered by dehydration.

Tips for Optimal Fluid Intake

Regular and Consistent Intake: It is important to consume fluids consistently throughout the day to maintain adequate hydration levels. This includes drinking fluids with meals and between meals, even when symptoms are not present.

Hydration Monitoring: Monitoring fluid intake can be beneficial, especially for individuals prone to dehydration. Keeping track of daily fluid consumption and adjusting intake as necessary can help maintain optimal hydration levels. One simple tip is to track the colour of urine – and try to keep this a clear or clear-yellow tinge. If you are producing minimal urine or the urine is dark yellow, then it is likely you need to increase fluid intake.

Electrolyte Balance: Ensuring an appropriate balance of electrolytes, such as sodium and potassium, can support proper hydration. In consultation with a healthcare professional, individuals may consider incorporating electrolyte-rich fluids or electrolyte supplements into their hydration routine. We prefer to advise a complex ground salt such as Himalayan Pink or Ground Sea Salt, but there are isotonic tablets (Nuun, ORS, SIS, Precision 1500) and chewable tabs (Vitassium)

Personalized Approach: Fluid requirements can vary among individuals, so it is important to work with healthcare professionals to determine individual hydration needs based on factors such as body weight, activity level, and overall health.


Fluid intake plays a critical role in managing symptoms of vasovagal syncope and orthostatic intolerance. Adequate hydration helps optimize blood volume, regulate blood pressure, and alleviate symptoms associated with dehydration. Consuming cold fluids can promote vasoconstriction and enhance alertness, while front-loading hydration in the morning can provide a boost to blood volume early in the day. It is crucial to adopt a personalized approach to fluid intake, working with healthcare professionals to determine individual hydration needs and incorporating strategies that support optimal hydration throughout the day. By prioritizing fluid intake, individuals with vasovagal syncope and orthostatic intolerance can improve their overall well-being and reduce the frequency and severity of symptoms.

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