Electrolytes are minerals that have an electric charge when they are dissolved in water or body fluids, including blood. They are essential for basic life functioning, such as maintaining electrical neutrality in cells and generating and conducting action potentials in the nerves and muscles. Electrolytes affect how the body functions in many ways, including:

• The amount of water in the body
• The acidity of the blood (pH)
• Muscle function
• Other important processes

Common electrolytes include sodium, calcium, potassium, chloride, magnesium, and phosphate. Electrolytes can be acids, bases, or salts, and they can be measured by different blood tests. Each electrolyte can be measured separately, such as ionized calcium, serum calcium, serum chloride, serum magnesium, serum phosphorus, serum potassium, and serum sodium.

Electrolytes are lost when the body sweats, and they must be replaced by drinking fluids that contain electrolytes. Water does not contain electrolytes. Signs of low electrolyte levels include fatigue, headache, nausea, blood pressure changes, muscle cramps, low energy, and not feeling well. Electrolyte solutions can also result from the dissolution of some biological or synthetic polymers, termed "polyelectrolytes," which contain charged functional groups.

Electrolytes are commonly found in fruit juices, sports drinks, milk, nuts, and many fruits and vegetables (whole or in juice form) . A home-made electrolyte drink can be made by using water, sugar, and salt in precise proportions. It is important to include glucose (sugar) to utilize the co-transport mechanism of sodium and glucose. Commercial preparations are also available for both human and veterinary use.