What should you know about sodium headache?

A high-salt meal can make the body retain water and may leave some people feeling thirsty, bloated or headachy. Too little fluid, sweating in hot weather, vomiting or diarrhoea can also disturb fluid balance. Sodium itself is not a diagnosis, and a headache after salty food does not prove that sodium caused it. Migraine, a viral illness, sinus symptoms, stress, poor sleep and medication effects can feel similar. Dehydration is one possible contributor; see our Dehydration guide for related symptoms.

Rest somewhere cool and quiet, sip water according to your thirst, and avoid adding extra salt while the headache settles. Keep a brief record of foods, drinks, heat exposure, sleep and symptoms so a clinician can look for a pattern. Do not make extreme changes to salt or water intake, especially if you have kidney, heart or hormone problems or take medicines that affect fluid balance. A GP consultation can help if headaches recur, change character or interfere with daily life.

Seek urgent medical help for a sudden, severe or rapidly worsening headache, confusion, fainting, weakness, trouble speaking, a stiff neck, repeated vomiting, a new headache after a head injury, or a headache with high fever. Get prompt advice if you cannot keep fluids down, are passing very little urine, or have a new headache during pregnancy. A persistent or recurring headache deserves assessment even when salty food seems to be a trigger.

Ask whether your symptoms fit dehydration, migraine or another cause; whether any medicine or health condition could affect sodium balance; and whether you need an examination or blood tests. Tell the clinician when the headache began, what you ate and drank, whether you were in heat, and which warning symptoms were absent or present.