Pain from a headache may occur on one side of your head (unilateral) or both (bilateral), and can change from time to time. It can range from mild to severe, and may feel like throbbing, stabbing, burning, or tight pressure. You may also have pain in your:

• Face, such as around your eyes or temples
• Jaw
• Neck

Other symptoms vary based on the type of headache, but common symptoms include:

• Increased sensitivity to light, sound, or smells
• Nausea and vomiting
• Dizziness
• Fatigue
• Changes in your vision
• Tearing or redness in your eyes

Headache pain can result from many complicated processes that involve the nerves in both your head and neck. Your brain receives pain signals sent by these nerves, resulting in a headache.

People who have a primary headache disorder like migraine, tension-type headache, or cluster headache may find there are times in their life when headaches occur more often, and times when they occur less often. Sometimes headaches may be triggered or impacted by many different factors, including:

Your environment

• Allergen exposure
• Bright or flashing lights
• Changes in weather
• Cigarette smoke
• Strong smells, such as chemicals or perfumes

Health issues

• Anxiety and depression
• Bacterial or viral infections
• Changes in hormone levels
• Temporomandibular jaw disorder (TMJ)

Lifestyle habits

• Changes in stress levels
• Dehydration
• Eye or neck strain
• Overexertion
• Skipping meals
• Sleeping too much or too little

Secondary headaches are when a headache is a symptom caused by a different underlying medical problem. Some of these can be dangerous, including:

Infections

• Meningitis, a bacterial or viral infection that causes inflammation in your brain
• Sinus infection (sinusitis)

Neurologic conditions

• Brain aneurysm
• Brain bleed (hemorrhagic stroke)
• Brain tumors
• Decreased cerebrospinal fluid (CSF) pressure around your brain (spontaneous intracranial hypotension or SIH) 
• Increased CSF pressure around your brain (idiopathic intracranial hypertension or IIH)
• Reversible cerebral vasoconstriction syndrome (RCVS), when blood vessels in your brain spasm and tighten

Other health conditions

• Certain medications, such as birth control pills, blood pressure medications, and hormone replacement therapy (HRT)
• Concussion
• Head or neck trauma
• Medication overuse
• Uncontrolled high blood pressure

There are more than 150 types of headaches. The most common headache types include:

Primary headaches

While the pain can be disabling, these headaches are not dangerous. Some of the most common types of primary headache include:

Migraine: Migraine causes throbbing, pulsing pain often on one side of your head (although it can affect any region of the head). A migraine can last from 4 to 72 hours if not treated. A migraine may occur fewer than 15 days a month (episodic migraine) or more than 15 days a month for three months or longer (chronic migraine). Other symptoms may include:

• Sensitivity to light, sound, or smells     
• Nausea or vomiting     
• Fatigue
• Brain fog
• Vision changes like aura or blurring (visual auras)
• Decreased appetite
• Dizziness or vertigo
• Increased urination
• Sweating

Tension-type headache: Tension-type headache causes mild to moderate pain in your forehead, temples, or neck that can last from hours to days. Other symptoms may include tight or painful neck and shoulder muscles.

Cluster headache: Cluster headache occurs only on one side of your head and lasts between 15 minutes to 3 hours when untreated. The pain can happen many times a day for days, weeks, or months. Other symptoms include:

• Droopy eyelid
• Enlarged pupil
• Increased eye tearing
• Red eye
• Stuffy nose on one side
• Sweating

Thunderclap headache: This extremely painful headache happens suddenly. It usually peaks within one minute and lasts at least five minutes. Thunderclap headache can also be a secondary headache related to another health condition. Other symptoms may include:

• Confusion
• Facial weakness or numbness
• Nausea or vomiting
• Problems with speech
• Seizures
• Vision changes

New daily persistent headache (NDPH): NDPH is a rare chronic headache that causes moderate to severe pain. This headache starts suddenly, continues every day, and lasts for at least three months. NDPH can also be a secondary headache related to another health condition. NDPH may include similar symptoms to a migraine or tension-type headache, such as:

• Dizziness
• Nausea or vomiting
• Sensitivity to light and sounds
• Visual auras

Secondary headaches

Because another health condition causes secondary headaches, we will do a thorough investigation if you start having these types of headaches unexpectedly. Types of secondary headache include:

Idiopathic intracranial hypertension (IIH): Increased pressure of the cerebrospinal fluid (CSF) around your brain occurs most often in women who are overweight. This can lead to headaches that are worse when lying down, as well as other symptoms, including:

• Vision loss
• Whooshing or ringing in your ears (tinnitus)
• Fatigue
• Nausea and vomiting
• Neck and shoulder pain

Post-traumatic headache (PTH): PTH occurs after a traumatic brain injury. It often causes pulsing pain and may include similar symptoms to a migraine or tension-type headache, such as:

• Difficulty concentrating
• Dizziness
• Insomnia
• Nausea and vomiting
• Personality or mood changes
• Problems with memory 
• Sensitivity to light and sound

Medication overuse headache: This type of headache is commonly known as rebound headache. This headache occurs when you overuse acute headache medications.

Intracranial hypotension: A number of processes, such as fluid leaking from a tear in the outer tissue protecting your brain (dura), can cause low pressure in the CSF around your brain. This can result in headaches that get worse when standing up and go away after lying down. Other symptoms may include:

• Brain fog
• Fatigue
• Nausea or vomiting
• Changes in vision or taste
• Dizziness or loss of balance
• Neck pain or stiffness
• Numbness in your face
• Tinnitus and other issues with hearing

Neuralgias

Neuralgia is pain caused by a damaged or irritated nerve. Common types of neuralgia include:

Occipital neuralgia: Occipital neuralgia causes piercing, throbbing pain starting at the base of your neck and spreading to one or both sides of your head. Occipital neuralgia can also be a secondary headache related to another health condition. Pain often occurs:

• Along your forehead and scalp
• Behind your ears and eyes
• In the back of your head 
• On your upper back

Trigeminal neuralgia (TN): Trigeminal neuralgia is chronic nerve pain that leads to intense episodes of pain on one side of your face. Pain may last from several seconds up to two minutes. TN can also occur as a secondary headache related to another health condition.