Nausea and vomiting may occur with many types of headaches, especially migraine headaches, and may continue for 8 to 24 hours. Nausea and vomiting with a headache that doesn't get better or go away may be a sign of another serious medical problem or serious illness, such as:

• Inflammation of the brain (encephalitis).
• Infection of the fluid and tissues that surround the brain and spinal cord (meningitis).
• A pocket of infection in the brain (brain abscess).
• Bleeding within or around the brain.

If ongoing nausea and vomiting occur with a headache, dehydration may become a problem. Dehydration can occur very quickly in young children and older adults. When you have a headache and prolonged nausea and vomiting, watch for signs of dehydration.