Answered from cited sources · retrieved September 20, 2026
what causes headaches
Headaches are classified as primary, which occur on their own, or secondary, which are caused by an underlying medical condition.
Headaches are generally categorized into two groups. Primary headaches occur on their own and are not symptoms of an underlying disease; they are often linked to overactivity or issues with pain-sensitive structures in the head, such as nerves, blood vessels, and muscles. Secondary headaches are symptoms of an underlying medical condition, such as an infection, injury, or other disorder. Many people have genetic predispositions that make them more sensitive to triggers, which can include lifestyle factors like stress, sleep changes, diet, and dehydration. During a headache, these triggers can cause nerves to send pain signals to the brain.
- Primary Headaches. Primary headaches are not caused by an underlying disease but result from issues with pain-sensitive structures in the head, such as nerves, blood vessels, and muscles. They are often influenced by genetics and lifestyle triggers like stress, poor sleep, and diet.
- Secondary Headaches. Secondary headaches are symptoms of another health condition, ranging from common infections like the flu or sinusitis to more serious issues like head injuries, brain tumors, or blood vessel disorders. Medication overuse is also a common cause.
- Common Triggers. Common triggers include emotional stress, lack of sleep, dehydration, skipped meals, poor posture, and certain foods or ingredients like alcohol, caffeine, or processed meats. Triggers are highly individual.
- How Pain Is Felt. The brain itself does not feel pain. Headaches occur when pain-sensitive nerve endings in the membranes, muscles, blood vessels, or nerves surrounding the skull respond to signals or triggers and send pain messages to the brain.
Sources
- Headache - Causes and definitionmayoclinic.org
- Headache | National Institute of Neurological Disorders and Strokeninds.nih.gov
- Headache: What It Is, Types, Causes, Symptoms & Treatmentmy.clevelandclinic.org · published August 29, 2022
- Overview of Headache - Brain, Spinal Cord, and Nerve Disorders - Merck Manual Consumer Versionmerckmanuals.com · published February 4, 2025
- Headachesnhs.uk
- Headache basics - Harvard Healthhealth.harvard.edu · published December 20, 2017
- Know Your Headaches: Causes, Types and When to See a Doctor | Cedars-Sinaicedars-sinai.org · published March 19, 2026
- Migraine and other headache disorderswho.int
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