When do you actually need electrolytes?

Electrolytes are minerals that play a vital role in the body, from helping you stay hydrated, through to supporting nerve and muscle function. They’re naturally abundant in fruits and vegetables, and in electrolyte type drinks, promoted to help you stay well hydrated when you need it most. So, how do you work out if and when you need electrolytes, and how much is enough? Let’s unpack this and delve into the science. 

What are electrolytes?

In science terms, electrolytes are substances that have a positive or negative electrical charge when dissolved in water. Almost every fluid and cell in the body contains electrolytes, and on a daily basis they play a vital role in maintaining internal fluid balance. Beyond this, they’re also vital for the body to function properly, as they also balance acid levels and control nerve and muscle function. When it comes to staying well hydrated, this is where electrolytes really shine. They help your body to hold on to and retain water, preventing dehydration. 

There are different types of electrolytes, the main ones being sodium, potassium, magnesium and calcium. 

Do you really need electrolytes?

Being so vital to proper body function, everyone needs electrolytes. If you’re low in electrolytes, you may experience a variety of symptoms such as dehydration, fatigue, muscle cramps and weakness. However, on a normal day to day basis, most people will get electrolytes as part of a balanced diet. 

Some common foods that contain electrolytes are:

• Sodium: Dill pickles, table salt, cheese, canned beans and tuna
• Potassium: Bananas, salmon, avocado, potatoes, mushrooms, coconut water 
• Magnesium: Spinach, pumpkin seeds, brown rice, almonds
• Calcium: Milk (dairy or calcium-fortified plant milks), cheese, spinach, tofu, yoghurt

Water is the best drink to choose daily, and water alone is usually enough to keep your body well hydrated. It’s part of a balanced diet, and aiming for 8-10 cups a day for most people is a good place to start. 

When to take electrolytes?

In some cases, you’ll need to top up your electrolytes through special drinks or supplements. This may be due to illness or increased physical activity, where your body experiences significant fluid loss from vomiting or diarrhoea  or heavy sweating.

Excess sweating due to exercise, heat or other cause

If you’re doing moderate to intense physical activity for an hour or more, you’re likely to lose enough fluid and electrolytes to need replacement. This may be true for shorter intense activity in warmer weather, or if you’re losing excess fluid through sweat due to other causes such as a fever or hormone related hot flushes. With excess sweating your body is losing significant amounts of sodium and other electrolytes and minerals. This can lead to signs of dehydration such as muscle cramps and weakness.  

Fluid loss through vomiting and diarrhoea 

In cases of gastro or food poisoning, you often find yourself losing fluid and electrolytes through vomiting, diarrhoea, or both. This rapid fluid loss can be difficult to replace, especially if you are not feeling 100%. Using an electrolyte drink can help your body retain and hold onto the fluid that it needs, while your body works hard to clear and resolve the cause of symptoms. 

Other illness 

Whether it’s sweating out a fever, or just not eating or drinking enough when you feel off, there are many other reasons why you may not be getting as much fluid and food (which contains electrolytes) as you need. 

How much electrolytes do you need?

There are a number of factors that determine your daily electrolyte needs, and it will change based on your level of activity and other circumstances. While there are recommended daily intake levels, these are not so much related to replenishing electrolytes lost through bodily fluids - they are targets from a dietary perspective on a day to day basis.

If you’re doing moderate to intense exercise for over an hour, you can try a few glasses of an oral rehydration solution or other electrolyte drink to help restore what you’ve lost. For cases of vomiting and diarrhoea, or illness, ask your pharmacist or doctor, or read product labels to ensure you get the right dose based on your fluid loss. 

Are there electrolyte alternatives?

On a normal day to day basis, drinking water will provide your body the fluid it needs. Eating a well balanced diet, with fruits, vegetables, wholegrains and protein sources, will generally provide plenty of electrolytes too. If you are looking to replace lost fluids and electrolytes, it’s best to choose a well formulated oral rehydration solution or electrolyte drink, to prevent and treat dehydration. However, some other electrolyte rich alternatives include coconut water, pickle juice and other fruit and vegetable juices. 

When to speak to a doctor

If you are showing signs of moderate to severe dehydration, you should always seek prompt medical attention. Severe dehydration can be very dangerous, especially for babies, young children and older people. Signs of severe dehydration include:

• extreme thirst
• fast heart rate
• low blood pressure
• cold hands and feet
• paleness and sunken eyes
• for babies - a sunken fontanelle the soft spot on the top a  baby’s head)

Speak to a doctor if you are wanting to try electrolyte drinks, and you have any of the following conditions:

• kidney disease
• heart failure
• diabetes

The bottom line

Most of the time, water and a well balanced diet will give your body the fluid and electrolytes it needs. If you are unwell, exercising more, or exposed to hot conditions, you may need to replace lost electrolytes with a well formulated product. If signs of severe dehydration appear, seek medical attention as soon as possible.  

Reviewed by the Healthylife health experts October 2025.