Dehydration Headache

Dehydration Headache

Almost everyone has experienced a headache at some point in their life. Most people can take an over-the-counter painkiller to treat it, while others need a prescription medication. But why do we get headaches, and can they be prevented by simple lifestyle changes? Thanks to research, we know about many common triggers – such as dehydration headache – and can use this information to help manage headache disorders.

Some key points about dehydration headache:

  • Dehydration is a trigger for 17% of people with migraine
  • 8 in 10 Australians don’t drink enough water
  • Sometimes you can be dehydrated even when you don’t feel thirsty
  • Dehydration is more than just not drinking enough water – you lose essential minerals (electrolytes), which is why electrolyte solutions are used to rehydrate quickly.

Headaches are a common symptom, with an estimated 1 in 2 adults affected by an active headache disorder globally (1). For some people, a headache might be an occasional symptom after a stressful day at work, or not getting enough sleep. But for others, headaches can be more frequent or severe, and begin to interfere with day to day life.

Some common headache disorders include migraine, cluster headache, and medication-overuse headache. Migraine is one of the leading causes of neurological disability worldwide, and over 4.9 million people in Australia are living with migraine (2).

The good news is that we understand much more about headache disorders than we did in previous decades. While there is no definitive ‘cure’ for migraine or many other headache disorders, research has led to new treatments and improved trigger management (including things like dehydration).

Common headache types

There are over 200 headache disorders recognised in the International Classification of Headache Disorders (ICHD-3). They are divided into three main groups (3):

  • Primary headache disorders are independent disorders, caused by specific pathological mechanisms. This includes things like tension headache, migraine, and cluster headache.
  • Secondary headache disorders are symptoms of another underlying disorder, ranging from mild head injuries to brain tumours.
  • Painful cranial neuropathies and other facial pains are very rare, but extremely painful. This includes conditions such as trigeminal neuralgia.

You can read more about many of these headache types in our headache type directory. Despite the huge number of headache disorders, the most common types are tension headache, migraine, and cluster headaches. These account for nearly 98% of all headaches (1).

Common headache disorders graphic
Common headache disorders table provided by Hydralyte® (1).

Headache triggers

These common headache types sometimes seem to happen for no reason, but they can also be brought on by ‘triggers’. A headache trigger can be any stimulus (environmental, dietary, physical, emotional, hormonal, etc) that contributes to the onset of a headache in a predisposed person (1). Some of the most common triggers include (4):

  • Stress
  • Sleep
  • Emotion
  • Weather/environment
  • Visual
  • Hormones
  • Food/eating habits (including dehydration) 
  • Smell/odor
  • Alcohol 
  • Activity/exertion

Sometimes, triggers are easy to identify – you might notice that you get a headache every time you don’t get enough sleep. But triggers aren’t always obvious, and they aren’t the same for everyone. You might find that a specific stimulus only triggers a headache some of the time, or your headaches are caused by a number of factors (4). Keeping a headache diary is a good way to monitor these environmental factors and your symptoms, giving you a better idea of what your triggers are.

Graph of common headache triggers, showing dehydration as the 6th most common cause.

Migraine Buddy went further and looked at trigger associations that may be influencing dehydration. These factors may also be triggers themselves with more complex and multifactorial roles.

Image source: Migraine Buddy 2021 data

For more information about the Migraine Buddy report, visit their article on dehydration.

Dehydration headache

Dehydration is more complex than just not drinking enough water. Not only is there less water in your body, but the composition and distribution of that water changes when you are dehydrated (1). You can become dehydrated if you don’t drink enough water, but it’s important to remember that exercise and hot weather can also cause dehydration.

We don’t know exactly why dehydration causes headache. However, water is essential for almost all biological functions, and plays a huge role in homeostasis (internal stability and normal bodily functions) (1). Given that people with migraine or headache disorders are more sensitive to environmental and physiological changes, it’s possible that the cellular dysfunction caused by dehydration can lead to headache.

Dehydration is also related to other common triggers. Exercise and hot weather are triggers for some people, and could be more likely to cause a headache when combined with dehydration. Other triggers such as stress, sleep, and hormonal changes can also affect homeostasis, and you might become dehydrated more easily after a stressful week or a poor night’s sleep (1). 

Managing dehydration

Unfortunately, many people don’t drink enough water to begin with. About 8 in 10 Australian adults don’t meet the recommended daily fluid intake of 2.6L for men, and 2.1L for women (1). 

Most people, under normal conditions, can drink enough water to stay hydrated. However, fluid losses can easily overtake your water intake if you aren’t drinking the recommended amount of water per day (1). Keep in mind that sometimes you might not notice, because thirst isn’t always a reliable indicator of dehydration. This is particularly true when you’re sick, if you have a chronic illness, and for older people – physiological changes and certain diseases affect how quickly you become dehydrated (1).

So what is the best way to manage dehydration? The best solution is always prevention, but if you do become slightly dehydrated, there are steps you can take to improve your body’s water balance quickly.

Managing dehydration graphic showing preventive strategies on one side and treatments on the other.

What are oral rehydration solutions?

An oral rehydration solution (such as Hydralyte) is able to replace lost fluids and electrolytes faster than water alone (1). Electrolytes are essential minerals that are vital for many key functions in the body. Oral rehydration solutions include minerals like glucose, sodium chloride, potassium chloride, and trisodium citrate, which provide effective rehydration (5). 

These are different to sports or energy drinks. While some sports drinks contain electrolytes, the most effective rehydration solutions have less sugar to provide the right electrolyte balance (1,5). 

The benefits of the Hydralyte range include (1):

  • Rehydrates faster than water alone
  • They have the correct balance of sodium and glucose (according to the World Health Organisation recommendations)
  • They are hypotonic – meaning they allow effective rehydration without side effects such as bloating
  • They are low-sodium, formulated specifically for the diets of developed countries
  • Low sugar
  • Suitable for all ages
  • Available in a variety of formats and flavours

If you have a headache disorder and find that dehydration is a trigger, you can keep oral rehydration solutions at home to help prevent headache or migraine attacks. Hydralyte is available from most major pharmacies and supermarkets in Australia. 

Further resources



  1. Hydralyte, 2021, Headache & Dehydration [fact sheet]
  2. Deloitte Access Economics, 2018, Migraine in Australia Whitepaper. 
  3. International Headache Society, 2018, The International Classification of Headache Disorders 3rd edition. 
  4. ABW Pellegrino, 2018, Perceived triggers of primary headache disorders: A meta-analysis. DOI: 10.1177/0333102417727535
  5. World Health Organization (WHO), 2006, Oral rehydration salts. Production of the new ORS. 

Headache AustralianMigraine & Headache Australia is the only organization in Australia that aims to support the more than 5 million Australians affected by headache and migraine.