Up to 80 percent of people suffer from an occasional tension headache: a dull pain across the forehead, temples, or around the back of your head. Anxiety, eye strain, fatigue, and stress can all trigger a tension headache by causing muscles to tighten in the neck and scalp. New research also suggests a link between tension headaches and changes in certain brain chemicals, similar to what happens with a migraine.

Treat It First With

Drink water, if you’re dehydrated. A 2004 study found that people who drank one-half to three-quarters of a liter of water lessened their headache pain. If after an hour or so you’re still suffering, you can turn to an over-the-counter pain reliever like acetaminophen (Tylenol and generic), ibuprofen (Advil and generic), or naproxen (Aleve and generic). Taking a hot or cold shower and resting in a quiet room with a cool cloth on your forehead may also help. (Find out whether acetaminophen or ibuprofen is better for a headache.)

If That Doesn’t Work

Check with your doctor to determine whether you have migraines or there’s another cause. Jaw clenching and teeth grinding in your sleep, for example, can trigger a tension headache. If you suspect your bite is to blame, see your dentist.

Get to an Emergency Room

If you have a headache that comes on suddenly, is severe, and persists, or you have speech, vision, or movement problems or a loss of balance, you should act. If you have a headache after a head injury, it could be a sign of a concussion.

Never Do This

Don’t take OTC pain relievers more than a few times per week because that could cause more headaches. (The same is true if you have migraines.) Also avoid CT scans. A severe headache may make you think you have a brain tumor, but that’s rarely true. Doctors can usually diagnose your pain based on your symptoms and a physical exam. If the exam results are abnormal or your doctor still can’t identify the cause of your pain, an imaging test can make sense. In most cases, an MRI is better than a CT scan, which can expose you to unnecessary radiation. That advice is supported by the American College of Radiology.

Prevent It in the First Place

Watch your alcohol intake because chemicals like sulfites and flavonoids can trigger headaches (and migraines). Control stress with meditation or other relaxation techniques. Getting enough sleep can also prevent headaches; so can staying hydrated.

Good posture can relieve neck stress and help avoid headaches, too. A 2015 Danish study found that people who suffered from tension headaches also had decreased muscle strength in the neck’s extensor muscles. That can cause the flexor muscles to overcompensate and pull the head forward, triggering a headache.

If you have headaches more than 15 times per month, your doctor may suggest a daily antidepressant such as amitriptyline (generic only), which has been found to help prevent chronic headaches but can also cause side effects such as drowsiness, weight gain, dry mouth, constipation, or blurred vision.

Editor's Note: This article and related materials are made possible by a grant from the state Attorney General Consumer and Prescriber Education Grant Program, which is funded by the multistate settlement of consumer-fraud claims regarding the marketing of the prescription drug Neurontin (gabapentin).

This article also appeared in the June 2016 issue of Consumer Reports magazine.