A migraine is an extremely severe paroxysmal headache usually confined to one side of the head. Migraines are often associated with nausea and hemicranias (a pain affecting one side of the head)1. Vomiting and extreme sensitivity to lights and sounds often also accompany a migraine.
A headache is a pain in any region of the head. Headaches may occur on one or both sides of the head, they may be isolated to a certain location or radiate across the head from one point, or have a vice-like quality. A headache can present as a sharp pain, a dull ache, or a throbbing sensation.
Primary headaches are caused by over activity or problems in pain sensitive structures in the head. Chemical activity in the brain, nerves or blood vessels surrounding the brain, or head and neck muscles can all play a role in the cause of a primary headache2.
Impact of coffee (caffeine) on migraines and headaches
Caffeine, and therefore coffee can have both beneficial and negative impacts on headaches and migraines. The benefits of caffeine are due to the anti-inflammatory properties it holds. Caffeine is included in many pain relievers, as it can make them up to 40% more effective, and studies have shown the last longer and work faster. Caffeine on its own has been known to stop headaches and migraines. Caffeine delivers pain relief via two distinct mechanisms: firstly, it exerts peripheral action, or relief at the site of the injury. In doing so, the caffeine acts directly on the muscle tissue, relieving pain by repairing tissue damage and reducing inflammation. Secondly, caffeine has a huge effect on the Central Nervous System (CNS) that results in the blocking of the pain signals between the CNS and the brain, and also increases the effects of the body’s own natural pain killing mechanisms.
Caffeine also has negative impacts on headaches, and on some occasions can cause them. Caffeine narrows the blood vessels that surround your brain. When you stop taking caffeine (or drinking coffee) they expand again and this can cause headaches to return.
Caffeine can also cause headaches, as it is a factor in medication overuse. This can happen when any kind of pain reliever is taken too often or in too large doses. When the medicine wears off, the pain comes back worse than before. This is most likely to occur with pain medications that have caffeine as an ingredient. It should also be remembered that caffeine is a drug, and when caffeine is consumed regularly, such as a cup a day, the body becomes used to the effects, and when it is no longer in the body, i.e. coffee is no longer being consumed, this causes the body to go into withdrawal. One symptom of withdrawal from coffee is a headache5.
SourcesWebMD -Caffeine Can Treat Migraines or Trigger Headaches, How to Avoid Rebound Headaches