Why dehydration can cause headaches and what to do about it

Key Points

• Headaches due to dehydration can occur when our bodies aren’t hydrated
• The pain of a headache due to dehydration may be mild, moderate or severe 
• It’s believed dehydration is one of the triggers of migraine

Nobody likes a headache. They hurt, they’re inconvenient, and they can really put a damper on your day. But what if the pain is trying to tell you something? In some cases, a headache may be a sign that you’re dehydrated.  

Thankfully, treating this is usually as simple as increasing your intake of the right type of fluids.  

 By learning about headaches due to dehydration and the importance of staying hydrated, you may reduce your chances of developing one. So, let’s jump in.

Why can dehydration sometimes cause headaches?

The term ‘dehydration headache’ isn’t actually an accepted medical diagnosis. You may get a headache when your body is out of whack due to dehydration, but it’s not known exactly why. 

What we do know is that dehydration can make various headache disorders worse – such as migraine. In addition to this, pain may be exaggerated when you’re dehydrated.

Why we should pay attention to headaches caused by dehydration 

As water makes up most of the human body (up to 80%, in fact), it’s no shock to learn that dehydration isn’t good for us. When we become dehydrated, our bodies usually send us signals to let us know – like giving us a headache.

 Headaches are one of the most common types of pain. You can probably recall the last time you had one. However, it can be hard to pinpoint their exact reason, so knowing that a headache is a symptom of dehydration is helpful.

What is dehydration?

Dehydration happens when you lose more fluid than you take in. It occurs when we don’t consume enough fluids or we lose the fluid our body holds faster than it should. Fluid loss can happen due to heat (sweat), vomiting, diarrhoea, and excessive exercise, among other factors.

 It’s not just water we lose when we’re dehydrated, either. We also lose electrolytes, which are minerals in the body that have an electric charge. Electrolytes help balance the amount of water in our bodies, help regulate the body’s acidity or pH levels, distribute nutrients into cells and waste out of cells, and assist in the functioning of the heart, muscles, nerves and brain. 

So, why is hydration important? Water helps our bodies to function as they should. When we don’t drink enough water, it can lead to mild dehydration. Symptoms include being thirsty, feeling dizzy or light-headed, having dark wee and as we’ve mentioned, a headache may be on the cards.

Speak to a healthcare professional if you’re experiencing symptoms of severe dehydration, which include

• extreme thirst and very dry mouth
• little or no urine
• rapid breathing rate
• rapid heart rate and low blood pressure
• fever
• confusion, irritability, sleepiness

We spoke with healthylife Advisory Board member and Registered Pharmacist & Nutritionist Sarah Gray, who says headaches related to dehydration can sometimes have a more serious underlying cause, but are usually resolved through adequate rehydration.

“If you’ve got signs and symptoms of severe dehydration, then you should speak to a healthcare professional.”

The symptoms of a headache due to dehydration should usually go away within a couple of hours of rehydrating

Other types of headaches to be aware of 

There are many types of headaches and many possible causes for them. But often, people don’t think much about why they have one. Instead, they try to treat it quickly and move on.  

Aside from a headache due to dehydration, other types of headaches you might experience include:

• Tension headache
  A headache that causes mild to moderate pain is usually referred to as a tension headache. This usually affects the head, face and neck, and is the most common type of headache.
• Cluster headache
  As the name suggests, a cluster headache is a series of headaches that may occur up to eight times a day and in weekly to monthly cycles. They usually present as severe pain on one side of the head. 
• Migraine
  A migraine is a common neurological disorder that can cause pain ranging from moderate to severe. Studies show migraine affects more than 4.9 million Australians. These throbbing, pulsing headaches can be accompanied by nausea, vomiting and sensitivity to light. 

If you have any signs or symptoms of a headache you are best to speak to your healthcare professional for advice. 

A headache due to dehydration can be mild or severe and can be a dull ache, throbbing or sharp pain

What does a headache due to dehydration feel like?

The feeling of a headache due to dehydration can vary for each person. The symptoms can be mild, moderate or severe. The pain may be in one area, like the back or front of your head, or all over. And it could present as a dull ache, a throbbing, or even a sharpness.

 Sarah explains that the pain will usually accompany other dehydration symptoms, which might give you a clue about its cause. 

“People might also experience darker urine, dizziness, thirst or tiredness,” she says. “If you have these signs and symptoms along with the headache, you’ll probably know it’s related to dehydration.”

Headaches related to dehydration, like any headache, can also vary in duration for everyone. 

“If you’ve made an effort to rehydrate and replenish electrolytes, as well as take some sort of pain medication as directed by a healthcare professional, it should probably go away in a couple of hours,” she says. “If not, please contact a healthcare professional”. 

If you’re experiencing severe, sharp or throbbing pain, see your healthcare professional as soon as possible. If a severe headache has come on suddenly and is accompanied by neurological symptoms like difficulty speaking or vision problems, go to the emergency department or call 000. 

How do you treat a headache due to dehydration?

These treatment options may help:

• Rehydrating with fluids
  Trying to drink more water is usually the best first step. Sarah also recommends drinking an oral rehydration solution. “These contain the perfect amount of electrolytes, sugar, salt, potassium and other things your body needs to kick hydration into high gear,” she says.
• Medication
  Taking over-the-counter pain relief medicine may help alleviate a headache from dehydration. However, Sarah recommends considering trying to fix the problem with fluids before reaching for the tablets. This varies for individuals, as it can be hard to identify that dehydration is the only reason you have a headache. 
• Prevention is the best cure
  The recommended daily water intake varies for everyone. As a rule of thumb, experts recommend drinking ten cups of water daily for men and eight cups for women. However, temperature, physical activity and health conditions must also be considered. A quick way to determine whether you’re getting enough water is to check the colour of your urine. A well-hydrated person will produce pale or straw-coloured urine. Someone who needs to drink more water will have darker urine.

Ensure you drink enough water every day

Stay hydrated – your body will thank you!

Your body is typically a good sounding board, so listen to what it’s telling you about hydration. Making an effort to drink enough water and stay in tune with your body will help support your overall health and wellbeing, as well as help prevent dehydration and associated headaches. 

If you’re experiencing regular headaches, severe pain or a headache that lasts more than 24 hours, visit your GP for a check-up. Learn more about the importance of hydration with healthylife’s drink more water program.

Related:

• Are you drinking enough water? 7 signs to find out
• Top 10 hydrating snacks and meals
• Are you hungry or thirsty? The link between hydration and appetite

Sarah Gray is both a Registered Pharmacist and Registered Nutritionist with a particular interest in health education and helping people to take small steps to big change in their health journey. Sarah is the General Manager of Health and Nutrition and a member of  the healthylife Advisory Board.

Reviewed by the healthylife Advisory Board January 2023