Most of us prepare for the possibility of dehydration during exercise or hot weather, but the truth is that mild dehydration happens any time your body does not have enough fluid to carry out its normal functions. Unlike severe dehydration, which requires immediate emergency care and is usually associated with extreme circumstances of illness, overexertion, heat exhaustion, and/or water deprivation, mild to moderate dehydration is often overlooked in our day to day lives. In fact, the simple sensation of thirst is an indication that your body is already mildly dehydrated.
Not drinking enough water during the day won’t just make you thirsty, though. Mild dehydration can also make you tired, dry out your skin, and make you dizzy or lightheaded, especially when standing up quickly. Your mouth can feel dry and sticky, and your head can certainly ache. And if you are chronically drinking less fluid than your body needs, these symptoms can become so normalized that you no longer realize they have anything to do with dehydration.
Current guidelines suggest that we should be all be getting 8 to 12 cups (64 to 98 ounces) of fluid from beverages each day to keep our bodies hydrated for normal, everyday activities. Of course this varies depending upon how much and what you eat, what the weather is, and how active you are. But it isn’t just the amount of liquid you drink in a day that matters when it comes to headaches; it’s also the type of beverage you choose to drink.
Except under severe dehydration circumstances, water is always the best choice for your body. In fact, your body would be perfectly content if you never drank anything else. Everyone should be making every effort to make plain water comprise at least 50% of the beverages you choose to drink each day. But many people enjoy a variety of beverages in addition to water, each with varying effects on overall hydration and head pain. If you suffer from frequent headaches, you may not only need more water, you may also need fewer of the following beverages in your diet:
Coffee, Tea, and Other Caffeinated Drinks
Caffeine can be both the cause and the treatment for many types of headaches. In fact, caffeine is a common ingredient in many prescription and over-the-counter headache medications, and it is estimated that caffeine additives may make pain relievers up to 40% more effective in treating headaches. The problem is that too much caffeine can cause both withdrawal and rebound headaches. And in excess of 500 to 600 mg per day (5 to 7 cups of coffee), caffeine will have a diuretic effect—causing excessive urination and dehydrating you, possibly making your head ache even more.
Sports Drinks, Soda, Juice, and Other Sugary Drinks
Unless you are an endurance athlete who exercises intensively for more than an hour at a stretch and sweats a lot, you don’t need a sports drink. Casual athletes and daily walkers are better off with plain water. In fact, any drink that contains added sweeteners, flavorings, colorings, or concentrated sugars can trigger headaches in individuals who are sensitive to artificial ingredients or spikes in blood sugar.
Excess blood sugar, or hyperglycemia, is directly related to dehydration; the body triggers the kidneys to allow extra urine to flow in order to get rid of the sugar and normalize blood glucose levels. If you continue to drink sugary beverages to replenish the water lost through extra urination, you only exacerbate the problem. This is especially true for diabetics, but even people who have not been diagnosed with diabetes can experience this reaction when eating or drinking more sugar than the body can metabolize. It’s a dangerous game to play with your body in the long term, and in the short term, it can definitely make your head ache.
The diuretic effects of alcohol are fairly significant. Alcohol blocks the release of an antidiurectic hormone in the body called ADH. This hormone is essential for water reabsorption in the body. Without it, the kidneys do not reabsorb the water passing through them, excreting it as urine instead. While many people are allergic to alcohol and/or sulfites, and can suffer from headaches when drinking on that basis alone, the primary trigger for a hangover headache is dehydration. And contrary to many popular “hangover cures,” the answer to a hangover headache is not more alcohol—it’s water.
Other Dehydrating Factors
Certain medication—including diuretics, antihistamines, blood pressure medications and some psychiatric drugs—can often have dehydrating side effects. We should all be sipping water throughout the day, but for those people taking one or more daily doses of medication, this is especially important. Headaches could be the result of the dehydrating effects of your medication. Always be sure to discuss any new, unusual, or severe headaches with your doctor when taking or changing daily medications.
Not all common headaches are related solely to hydration. Many are multifactorial, with dehydration being only one part of the whole picture. Mild dehydration can make you tired, for example, which can lead you to slouch at your work desk. Your head may ache partly because you need more water, but the other part of that headache might be related to the muscle strain created by bad posture. If you know you haven’t had anything to drink in a while, though, a glass of water is always a good place to start when you realize you have a headache.
Harvard School of Public Health: Healthy Beverage Guidelines
Mayo Clinic: Dehydration
Mayo Clinic: Caffeine: Is it Dehydrating?
Nutrition Reviews: Water, Hydration, and Health
WebMD: Migraines, Headaches, and Caffeine
U.S. National Library of Medicine: Diabetic Hyperglycemic Hyperosmolar Syndrome
U.S. National Library of Medicine: Alcohol Hangover: Mechanisms and Mediators
The Headache Series:
Daily Headache Diary
Exercise, Rest, and Stress
Jaw Injuries and Muscle Strain
Hormones, Medication, and Environment
Hydration (information on this page only)
The Full Headache Series (entire series including Daily Headache Diary)
Daily Headache Diary (with instructions)
Daily Headache Diary Form (form only, no instructions)