What should you know about horrible headache?

Headache may follow dehydration, heat, poor sleep, a common cold, allergic rhinitis, sinus inflammation, stress or muscle tension. Migraine can cause throbbing pain with nausea or sensitivity to light and sound. Fever, neck stiffness, weakness, confusion, vision change or a new rash changes the level of concern. A headache that starts suddenly at maximum intensity, follows a head injury, or is new in pregnancy or with very high blood pressure needs prompt clinical judgement.

Move to a quiet place, drink fluids and rest your eyes. Eat if you have missed meals, cool down after heat exposure and keep a note of onset, duration, location, triggers and associated symptoms. Use only pain relief that is suitable for you and follow the label or a clinician's advice; repeated use can itself contribute to headaches. Arrange review for a new, recurrent or worsening pattern, or when headaches are affecting sleep, work or usual activity.

Seek emergency help for a sudden explosive headache, new weakness or numbness, trouble speaking, confusion, fainting, seizure, severe vision change, stiff neck with fever, repeated vomiting or a rapidly spreading rash. Get prompt advice after a head injury, during pregnancy, or when a headache is steadily worsening or unlike your usual pattern.

What headache pattern do my symptoms suggest? Could dehydration, heat, infection, vision strain or medicines be contributing? Which changes mean I should seek emergency care?