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Dehydration and Headaches: Does Dehydration Cause Headaches?

How to Avoid Getting a Dehydration Headache

By Rachel Kelley

Updated January 27, 2009

(LifeWire) - Does Dehydration Cause Headaches?

Yes, dehydration can cause headaches. Dehydration is the loss of water and electrolytes, such as sodium, chloride and potassium, which are necessary for the body to function. The main cause of dehydration is not drinking enough water to maintain healthy levels. A variety of unpleasant symptoms occur when this happens, including headaches. Severe dehydration is serious and potentially life threatening.

What are the Symptoms of Dehydration?

The initial symptoms of dehydration include thirst and minor discomfort. Symptoms can progress to headache, fatigue, weakness, constipation, parched lips, dizziness, dry or flushed skin, rapid heartbeat and muscle cramps. Typically, there's a decrease in urine output and the urine is dark or amber in color. More severe signs are low blood pressure, swelling of the tongue, and unconsciousness and death in the most extreme cases.

What Does a Dehydration Headache Feel Like?

Writing on this subject for Intelihealth.com, Howard LeWine, MD, a clinical instructor of medicine at Harvard Medical School and Boston's Brigham and Women's Hospital, explained that the pain from a water-deprivation headache may occur at the front or back or just on one side of the head, or it may be felt throughout the entire head. Bending the head down or moving it from side to side often worsens the headache. Simply walking can cause more head pain, LeWine noted.

"Dehydration causing headaches is much more common than is generally recognized in the medical profession," he said in a telephone interview.

What's Happening in the Body When You Have a Dehydration Headache?

It's not known precisely how dehydration causes headaches. According to some experts, it's a by-product of the body's effort to maintain adequate fluid levels. The blood vessels narrow, reducing the brain's supply of blood and oxygen. According to LeWine, the brain can't feel pain, so the headache discomfort may result from pain receptors in the lining that surrounds the brain. The loss of electrolytes may also contribute to dehydration headaches.

How Do You Get Rid of a Dehydration Headache?

Drink water! LeWine recommends drinking 16 to 32 ounces of water for improvement, which should be evident within one to two hours. For severe dehydration, the person should lie down and drink more fluids. In extreme cases, intravenous rehydration may be necessary.

How Can You Avoid a Dehydration Headache?

In general, the key is not allowing oneself to get thirsty in the first place. Maintain an adequate fluid intake and eat foods that are naturally high in water content, such as vegetables and fruits.

Not all fluids are equal when it comes to fluid replacement. Coffee and alcohol are bad choices -- both act as diuretics, which promote urination and fluid loss, and cause dehydration and headaches.

What about sports drinks that contain sugar and electrolytes? When asked whether sports drinks or plain water was the better choice, Dr. LeWine said, "There's not any solid evidence one way or the other..."

It's particularly easy to neglect fluid replacement when exercising or engaging in strenuous activity, or when sick with an illness that causes vomiting or diarrhea. These are times when special precautions should be taken to make sure you replace the fluids you lose.

Sources: LeWine, MD, Howard. "Ask the Expert: Can Dehydration Cause Headaches?." Intellihealth.com. 24 April. 2006. Aetna Intellihealth. 29 Mar. 2008 <http://www.intelihealth.com/IH/ihtIH/WSIHW000/4464/8480/465540.html>.

LeWine, MD, Howard. Telephone interview. 27 Mar. 2008.

Mayo Clinic Staff. "Dehydration."  MayoClinic.com. 3 Jan. 2007. The Mayo Clinic.. 29 Mar. 2008 <http://www.mayoclinic.com/print/dehydration/DS00561/DSECTION=all&METHOD=print>.

"Does Anything Work When Battling a Hangover?." abcnews.go.com. 1 Dec. 2005. ABCNews Internet Ventures. 21 Mar. 2008 <http://abcnews.go.com/GMA/Health/story?id=1458572>.

"Headaches." Brown University Health Education. 4 Mar. 2008. Brown University. 21 Mar. 2008 <http://www.brown.edu/Student_Services/Health_Services/Health_Education/general_health/headache.htm>.

"Dehydration." Medline Plus. 28 Sept. 2007. US National Institutes of Health. 21 Mar. 2008 <http://www.nlm.nih.gov/medlineplus/ency/article/000982.htm>.

"Headache Triggers." CIGNABehavioral.com. CIGNA Insurance. 21 Mar. 2008 <http://apps.cignabh.com/web/basicsite/bulletinBoard/headacheTriggers.jsp>.

LifeWire, a part of The New York Times Company, provides original and syndicated online lifestyle content. Rachel Kelley has been an editor and writer for 8 years. She has degrees in nursing, psychology and education.

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