What should you know about electrolytes after vomiting?

Vomiting loses fluid containing salts such as sodium and chloride. If losses continue, dehydration may cause thirst, dry mouth, darker urine, tiredness, dizziness or a fast heartbeat. The cause may be a short-lived stomach infection or food poisoning, but repeated vomiting can also accompany migraine, gallstones or pancreatitis.

The amount lost and your ability to keep drinks down matter more than trying to calculate an exact replacement. Children, older adults and people with kidney or heart conditions can become unwell more quickly.

When vomiting eases, take small sips of an oral rehydration solution or clear fluid at frequent intervals. If it stays down, gradually increase the amount and then try bland foods. Avoid gulping a large drink, alcohol and very sugary drinks, which may worsen nausea or diarrhoea.

If vomiting returns, pause briefly and restart with smaller sips. A pharmacist or clinician can recommend an appropriate rehydration product, especially for a child or someone with a long-term illness. Do not use salt mixtures made at home unless a professional has given exact instructions.

Get urgent medical help for blood or green vomit, severe or worsening abdominal pain, a stiff neck with severe headache, confusion, fainting, breathing difficulty, or inability to keep fluids down. Arrange prompt review for very little urine, severe dizziness, persistent vomiting or signs of dehydration. Read more about vomiting if symptoms continue.

Which rehydration drink is suitable for me? How much should I take at a time? Could my medicines or medical conditions change the plan? Which symptoms mean I should attend an emergency department?