Dehydration headache: what to know

Fluid loss can follow sweating, fever, vomiting, diarrhoea, or drinking too little. The headache may feel dull or throbbing and worsen with movement. Thirst, dry mouth, tiredness, dizziness, and dark urine can support dehydration as a contributor, but headaches have many causes.

Improvement after fluids does not prove dehydration caused the pain. Heat exposure, infection, migraine, missed meals, poor sleep, and medicines may also be involved.

Rest somewhere cool and quiet. Sip water steadily rather than drinking a large amount quickly. After vomiting, diarrhoea, or heavy sweating, an oral rehydration solution may help when used as directed. Eat if you missed meals and avoid alcohol.

If headaches recur, note fluids, urine changes, heat exposure, and associated symptoms so a clinician can assess the pattern.

Seek emergency help for a sudden extremely severe headache, new weakness, trouble speaking, fainting, confusion, seizure, stiff neck with fever, or repeated vomiting. Arrange review for a new or recurring headache, pain after head injury, or symptoms persisting despite rest and fluids.

Ask whether dehydration fits the pattern, whether another headache cause is possible, and which pain medicines suit your conditions and regular medicines.