Staying well-hydrated is important for overall health. Having enough fluids and electrolytes in the body ensures that everything is running as it should. If a person gets dehydrated, they can experience unpleasant symptoms such as dizziness, fatigue, or headache, which may be signs that the body needs fluids.

A headache caused by mild dehydration is usually nothing to worry about, and it should go away on its own after drinking water or an electrolyte-rich drink. However, some instances of a dehydration headache can be a little more serious, such as when there is an illness causing the dehydration.

This guide from HealthTap looks at the causes of dehydration headaches, what the signs and symptoms are, and how they can be treated and prevented. 

What is dehydration?

Staying well-hydrated helps the body maintain many vital functions, such as regulating body temperature, keeping the joints lubricated, and delivering oxygen and other nutrients to the cells. 

Dehydration happens when the body doesn’t have enough water or electrolytes like sodium and potassium. Electrolytes are minerals that have many functions inside and outside the cells. They’re just as important as water in keeping up hydration levels. 

People generally feel thirsty whenever their bodies need more fluids, and they drink to end the thirst. Thus, dehydration is uncommon in healthy people, but tends to happen during illnesses where fluids are lost (such as diarrhea) or in situations where people are unable to obtain or drink fluids. Depending on how severe the dehydration is, it can cause problems with many of the body’s functions, such as digestion, circulation, waste removal, and even cognitive function.

What are the signs of dehydration?

Here are five of the most common dehydration signs. 

1. Dark urine or little urine

Due to certain pigments in urine, the color of urine can range in color from clear to yellow to amber. When the pigments are diluted with water, the color of urine becomes lighter. On the other hand, without much fluid, urine tends to take on a darker shade. 

This makes both the color of urine and the amount of urine output excellent indicators of hydration. As a rule of thumb, urine that’s clear or light yellow is a sign of good hydration. On the other hand, dark yellow urine is a sign of dehydration — it’s likely to see this darker color when the amount of urine is small and bathroom trips are not very frequent.

2. Dry mouth 

Saliva has many antimicrobial and antiviral properties, which makes it important for keeping the mouth healthy. In addition, saliva contains digestive enzymes, which are mixed with food when chewing and help to support healthy digestion.

When someone is dehydrated, their salivary glands don’t have enough fluid to produce saliva. This can lead to a dry or sticky mouth, which makes it harder to chew food or swallow. Dry mouth caused by dehydration can also be accompanied by bad breath. 

3. Dizziness 

When the body doesn’t have enough fluids circulating, it can lead to a decrease in blood pressure. When blood pressure drops, important nutrients such as oxygen don’t make it to the brain in enough amounts, which can create the sensation of dizziness. 

Of course, dizziness is a symptom of many health conditions. For this reason, dizziness by itself shouldn’t always be taken as a sign of dehydration. In combination with other dehydration symptoms, dizziness is more likely a sign of low fluid levels. 

4. Fatigue 

Another effect of the brain not getting enough oxygen is fatigue. Fatigue can also happen when the heart has to work overtime to pump blood and deliver important nutrients to the rest of the body. This increased workload can lead to more energy spent, which can make someone feel more tired than usual. 

5. Headache

A headache can be a symptom of many health conditions, including dehydration. The next section will go over why head pain happens. 

Why does dehydration lead to headaches?

To function properly, the body requires a balance of fluids and electrolytes including sodium, potassium, and calcium. Some of the causes of dehydration occur because the body is losing fluids and electrolytes through sweating and urinating, without drinking enough replacement fluids.

Most of the time, these fluids and electrolytes can be easily replenished with water, other beverages, and even some water-rich foods. But in some cases, a person can lose more fluids and electrolytes than they can replenish in time. When this loss is enough to change how the body functions, that’s dehydration.

Dehydration can cause headaches because the brain can temporarily shrink a little bit away from the inner surface of the skull, which leads to pressure on some nerves and blood vessels. A possible sign that the headache was caused by dehydration is if drinking water or another beverage is enough to get rid of the headache. 

What are the signs and symptoms of a dehydration headache?

Unlike other types of headaches, such as migraine headaches, tension headaches, and sinus headaches, a dehydration headache tends to be mild with a dull all-over ache. The pain can occur anywhere around the head, including the front, back, or sides, and often gets worse with physical activity. 

The symptoms of a dehydration headache include pain around the head and classic symptoms of dehydration, such as dark-colored urine, extreme thirst, dizziness, fatigue, rapid heart rate, and dry mouth. 

In extreme cases, a dehydration headache can be accompanied by more intense symptoms such as lack of sweating, decreased urination, shriveled skin, sunken eyes, and delirium. The last symptom is especially common in older adults, who are at higher risk of chronic dehydration. 

Sometimes, even mild dehydration is enough to cause a dehydration headache, which can be due to something as simple as not drinking enough water on a hot day. 

However, dehydration also frequently happens as a result of something that caused the body to lose fluids at a faster rate, such as:

• Vomiting

• Diarrhea

• High fever

• Being outside in extreme heat

• Kidney disease causing excess urination

In extreme cases, drinking more fluids may not be enough to bring relief, and medical advice should be immediately sought. The following section gives an overview of how dehydration headaches are treated in mild, moderate, or severe cases. 

How is a dehydration headache treated? 

To treat a dehydration headache, fluid replenishment is the first thing that has to be addressed. 

In mild cases, rehydration can be accomplished at home by drinking water or other fluids. It might also help to have electrolyte intake, which can be done by drinking a sports drink. Because caffeine is a natural diuretic (meaning it makes the body get rid of fluids faster), it should be avoided when someone feels dehydrated and other drinks are available. 

In cases of severe dehydration, intravenous (IV) fluid therapy may be necessary. A clinic or emergency room can administer fluids with electrolytes via an IV line to help fluids reach the bloodstream faster than drinking. Proper IV rehydration helps prevent serious medical complications like kidney failure, hypotension (extremely low blood pressure), or hypokalemia (dangerously low potassium levels). 

Getting rid of dehydration can make a dehydration headache resolve on its own. However, if the pain is uncomfortable, some people take an over-the-counter pain reliever such as acetaminophen or ibuprofen for pain relief. 

How can a dehydration headache be prevented? 

To prevent a dehydration headache, the most effective approach is to stay well-hydrated. This can be done with the following tips: 

• Drink (or eat) enough fluids
  It’s important to drink enough fluids and consume water-rich foods throughout the day. Light-colored urine is a likely sign that enough fluids are being consumed. 

• Increase hydration when sweating
  When being outside in hot weather or engaging in intense physical exercise, it’s important to drink more water. Low-calorie sports drinks can also be a great solution. 

• Treat underlying causes
  Some people can have chronic illnesses or even temporary sicknesses that make them lose fluids at a faster rate. For instance, when someone has food poisoning, they can lose a lot of fluid through vomiting and diarrhea. If not replenished, this can lead to dehydration. 

• Avoid over-the-counter diuretics
  Diuretics are substances that make the body get rid of water at a faster rate, usually through urination. To keep a proper bodily fluid balance, it’s important to discuss with one’s doctor how to avoid dehydration if using diuretics for medical reasons.

Staying well-hydrated is good for health 

Hydration is important for virtually all of your body’s functions, such as digestion, circulation, and cognition. Even being mildly dehydrated can disrupt these functions and lead to uncomfortable symptoms such as fatigue, dizziness, and headache.

If you’re experiencing dehydration headaches that don’t go away with drinking more water, an underlying medical condition may be to blame. 

HealthTap can connect you with an affordable health care provider to help you get to the root cause. Make an appointment today with a HealthTap primary care doctor to begin your health and wellness journey.