Heavy Sweating

When your body heats up and you start to sweat, dehydration can follow. It’s important to replace those lost fluids, whether you’re sweating due to exercise, work, illness or just being out and about in hot weather.

Sweating is part of your body’s natural cooling process – once your body starts to heat up it begins pumping out sweat from millions of glands all over your body to help you cool down. If the fluid lost through excessive or prolonged sweating is not replaced it’s easy to become dehydrated. When this happens you can’t sweat as much, so you can’t cool down as effectively and your body temperature may start to rise – and this may eventually lead to serious problems such as heat stress or heat stroke.


Why do we sweat?

Sweating is the main way the body cools down

The human body likes to keep itself at around about 37oC – that’s the ideal temperature at which all our body’s various systems function properly. When we’re exercising, working hard or have a fever we’re also producing heat that can start to raise our body temperature and so we sweat to help maintain a steady 37oC core body temperature.

When we’re hot our bodies pump more blood into the small capillaries at the skin’s surface to help radiate some of the extra heat away. Sweating helps increase the amount of heat lost – as a drop of sweat on your skin evaporates (turns into water vapour) it extracts a small amount of heat from the skin and creates a cooling effect. The more you sweat, the more evaporation occurs, the more your skin (and circulating blood) is cooled – and the more likely you are to become dehydrated if you’re not replacing the fluids lost in sweat!

But there’s more going on when we sweat than just temperature regulation and there are a number of different situations that we may find ourselves in that can cause sweating, including:

  • Hot environments
  • Exercising
  • Emotional stress (such as anxiety or fear)
  • Eating hot or spicy foods
  • Having a fever (linked to an illness).


Did you know you have more than one type of sweat gland?

In fact, there are three different types of sweat glands, producing different types of sweat:

  • Eccrine sweat glands – are the most common type of sweat gland that produces most of the body’s sweat and are found across nearly all of the skin’s surface. Eccrine sweat is made up of mostly water and salt. The highest gland densities are found on the palms and soles of your feet where they respond to both emotional and heat triggers – whereas the majority found on the rest of the body are mostly involved in heat regulation.
  • Apocrine sweat glands – react to emotional stimuli producing more oily secretions through your hair follicles (rather than directly onto the surface of the skin as eccrine glands do) and are found in the hairier skin areas such as your scalp, armpits and groin.
  • Apoeccrine sweat glands – have only been identified relatively recently and appear to be similar to eccrine glands as they secrete watery sweat directly on the skin surface, but like apocrine glands they are found in the armpit areas and react to similar triggers.


Sweating and dehydration

Dehydration occurs, in most instances, for the simple reason that you’re not drinking (or eating) enough fluids to replace those your body is losing through things like urine, diarrhoea or vomiting, and sweating.

Anyone can become dehydrated – but some ‘everyday’ occasions have a higher risk for developing dehydration linked to sweating, including:

  • Being out and about in hot weather (whether it’s for leisure or work) means our bodies have to work overtime to keep cool – there is lots of sweat being produced and lots of water being lost!
  • Prolonged or vigorous exercise can also lead to large amounts of sweating as our bodies try to dissipate the heat being produced by all the physical activity going on – and dehydration can be more of an issue if you are exercising in hot, humid conditions.
  • When we are sick with a fever our body sweats to try and reduce our temperature and this can then increase the likelihood of dehydration – particularly if you are also vomiting or have diarrhoea.


Be prepared and manage your dehydration before it becomes a problem

  1. Be prepared and manage your dehydration before it becomes a problem
    • Sticky mouth or dry mouth
    • Increased thirst
    • Lethargy
    • Decreased urine output
    • Dark yellow urine.
  2. Regularly replace lost fluids with an oral rehydration solution – like Hydralyte – that contains the correct balance of fluid, electrolytes and glucose.


Hydralyte is specifically formulated to help replace water and electrolytes lost due to dehydrating conditions including excessive or heavy sweating. The formulation is based on the World Health Organisation criteria for effective rehydration. Water alone, or sugary drinks, are not as effective as Hydralyte.