Primary headaches are caused by changes to blood vessels, nerves, and chemicals in the brain. Secondary headaches are caused by another condition, such as an infection or head injury.

Your symptoms can help you figure out which type of headache you’re experiencing. Read on to learn more.

Common headache triggers include:

Dehydration

Having too little fluid in your body can trigger headaches. If your headache appeared after sweating, vomiting, or a bout of heavy drinking, it could be related to dehydration.

Screen brightness

Staring at your computer monitor or TV screen for hours at a time strains your eyes, which can cause headaches.

If your headache started after a marathon work session, it should pass if you close your eyes or look away from the screen for a couple of minutes.

Eating and sleeping patterns

Skipping meals deprives your brain of the sugar (glucose) it needs to run efficiently. Regularly waking up in the morning with a headache could be a sign you’re not sleeping well.

Hormones

Declining estrogen levels alter the release of brain chemicals that contribute to headaches. Headaches that pop up around the time of your period could be hormonal.

Posture

Poor posture puts strain on your upper back, neck, and shoulders that may trigger a headache. Headaches that start after you’ve been slumped over your desk or sleeping at a funny angle could be postural.

Lack of physical activity

A fast run on the treadmill or bike ride releases painkilling hormones called endorphins. People who don’t exercise enough may get more frequent and severe headaches.

Overexertion

Working out too hard can inflame the blood vessels in your head. Some people get exertional headaches after an intense session of exercise or sex.

Medication

Some of the medicines that relieve headaches can actually lead to more headaches if you take too much of them or use them too often.

Regularly taking nonsteroidal anti-inflammatory drugs (NSAIDs), triptans, opioids, and caffeine can all cause this rebound effect.

Stress

Stress makes your muscles tighten up and alters levels of brain chemicals that contribute to headaches. Tension-type headaches are common in people who are under a lot of stress.

Noise

Extremely loud or prolonged sounds can trigger migraines and other headaches. Any loud noise — from a rock concert to a jackhammer — can set off head pain.

A primary headache is caused by a problem with the nerves, blood vessels, or chemicals that sets off pain signals in your brain. It’s not related to any other disease.

Different types of primary headaches include:

Tension headache

This is the most common type of headache. Up to 80 percent of Americans get tension headaches from time to time.

Tension headaches come in two types:

  • Episodic tension headaches last from 30 minutes to a week. They occur less than 15 days a month.
  • Chronic tension headaches can last for hours and happen more than 15 days a month.

Tight muscles in the neck and head can set off tension headaches. Stress, a lack of sleep, and poor posture can all contribute to the pain.

Feels like: A dull, achy pain with a feeling of pressure around your head. The pain can extend to muscles in your scalp, neck, and shoulders.

Migraine

Unlike a traditional headache, migraines typically cause more than just head pain.

Some people experience migraines from time to time, while others get them several days each month. Overall, women are more likely to develop migraines than men.

Feels like: Throbbing pain on one side of the head, sometimes with nausea and vomiting. Movement, light, and sound may make the pain worse.

Migraine with aura

Aura is a collection of sparks, flashes of light, and other sensory symptoms that appear just before a migraine attack. The aura may last up to an hour before the migraine starts.

About a quarter of people who have migraines also experience aura.

Feels like: Floating lines of light, shimmering spots, flashes of light, or vision loss before or during a migraine. You might also have numbness or tingling in your body and trouble speaking.

Cluster headache

These headaches are named because of their pattern. They strike in clusters, with intense headaches every day or several times a day for a period of four to six weeks. Then they disappear during a pain-free remission that lasts for six weeks to a year.

Cluster headaches are rare. Less than 1 percent of people get them.

Feels like: Intense pain on one side of your head, usually around your eye. The pain can radiate to your neck and shoulders. You may also experience red, teary eyes or a runny nose.

Other types

Other types of primary headaches are less common, and are often triggered by a specific activity:

Cough

These uncommon headaches start when you cough. They’re caused by a rise in abdominal pressure from straining. Laughing, blowing your nose, and bending over can also cause this type of strain and result in a headache.

Exercise

Intense exercise like running or weightlifting can bring on this type of headache. The headache starts while you’re exercising or after you’re finished. It feels like a throbbing sensation.

Sex

This type of headache is triggered by sexual activity — especially orgasm. It can take the form of a dull ache in your head that intensifies as you become more excited. Or, it can come on suddenly and intensely at the moment of orgasm.

Secondary headaches are often caused by a minor head injury or medication overuse.

They’re also associated with underlying medical conditions, such as:

Unlike primary headaches, secondary headaches come on quickly. They can be very severe.

Different types of secondary headaches include:

External compression headache

These headaches start after you’ve worn something tight around your head, like a helmet or goggles. They’re sometimes called “football-helmet” or “swim-goggle” headaches.

People who wear helmets or goggles for work, such as military members or police officers, are more likely to get external compression headaches.

Feels like: Pressure around your head that worsens the longer you wear the headgear. The pain goes away within an hour after you remove the object.

Rebound headache

These headaches affect people who often use pain relievers to treat migraines. Overuse of these medicines can cause withdrawal, which leads to more headaches.

These are also called medication-overuse headaches.

Drugs that cause rebound headaches include:

  • acetaminophen (Tylenol)
  • NSAIDs like ibuprofen (Advil) and naproxen sodium (Aleve)
  • over-the-counter headache remedies that contain caffeine
  • migraine drugs, such as triptans (Imitrex) and ergotamine (Ergomar)
  • narcotics like codeine

Drinking coffee or other caffeinated beverages daily can also lead to rebound headaches.

Feels like: Daily headaches that improve when you take pain medicine, and then start again when the medicine wears off.

Sinus headache

These headaches cause pain and pressure in the sinuses. A sinus headache is typically related to a migraine or tension headache and not to a sinus infection.

Feels like: Pain and pressure behind the eyes, cheeks, and forehead, and aching in the teeth. The pain is similar to a migraine. The headache may get worse if you bend over or lie down.

Spinal headache

This type of headache is caused by fluid leaking from the membrane around the spinal cord. The fluid loss lowers pressure around the brain.

Up to 40 percent of people who have a spinal tap or spinal anesthesia will get this type of headache.

Feels like: Dull, throbbing pain that gets worse when you sit up or stand and improves when you lie down. You might also feel dizzy and have a ringing in your ears.

Thunderclap headache

These rare headaches come on quickly and intensely, like a bolt of thunder. There aren’t any obvious triggers for the pain.

Thunderclap headaches can warn of a serious problem, like bleeding, a stroke, or a blood clot in the brain.

Feels like: An intense burst of pain that peaks within 60 seconds and lasts for at least five minutes. You may also experience nausea, vomiting, and fever. Seizures are also possible.

Thunderclap headaches are a medical emergency and you should seek medical treatment if you have a thunderclap headache.

You may be able to ease your symptoms if you:

  • Apply a heating pad to your neck to relax tense muscles associated with tension headaches.
  • Apply a cool compress to your forehead and cheeks to relieve sinus headaches.
  • Turn off the lights and quiet any sound sources like the TV. Loud noises aggravate migraines.
  • Have a cup of coffee. Just don’t overdo it. Too much caffeine can trigger more headache pain.
  • Meditate. Breathe deeply and focus on a word or chant. Meditation can calm both your mind and body, and it can relieve any stress that might have set off your headache.
  • Eat regular meals and snacks throughout the day. Drops in blood sugar can set off headaches.
  • Take a walk. Exercise can release pain-relieving chemicals.

See a doctor right away if you experience:

  • severe pain
  • confusion
  • high fever
  • numbness or weakness on one side of your body
  • stiff neck
  • trouble speaking
  • vision loss
  • difficulty walking

You should also see a doctor if your symptoms don’t improve with treatment or worsen over time.