How to recognize and treat a dehydration headache

From stress and caffeine withdrawal to genetic predisposition, there are loads of reasons why you might get a headache on a regular basis. But one often overlooked, but common cause is dehydration, even mild dehydration can cause headache pain. Here, learn how to determine if dehydration is contributing to your pain, plus steps you can take to manage symptoms and prevent them from recurring in the future. 

What is a dehydration headache?

There are many levels of dehydration, which is defined simply as your body not having as much water or fluid as it needs. These levels range from mild dehydration, which can cause feelings of thirst from not drinking enough fluids or sweating a lot, to severe dehydration, which can cause dizziness or a rapid heartbeat and even be life-threatening.

Headaches typically occur in the mild to moderate stages of dehydration. “Dehydration can cause headaches through various mechanisms,” explains Adam Siwek, DO, an interventional pain specialist at The Pain Center of Arizona in Phoenix. “When the body lacks an adequate amount of water, the blood volume decreases, leading to reduced blood flow and oxygen to the brain. This, in turn, can trigger a headache.”

In addition to reducing blood flow, dehydration can also cause narrowing of the blood vessels in the brain, adds Dr. Siwek, which further contributes to headache pain. 

What does a dehydration headache feel like?

“Dehydration headache most often has the appearance of a tension-type headache,” says Eric Baron, DO, a neurologist at the Cleveland Clinic Center for Neurological Restoration – Headache and Chronic Pain Medicine, in Cleveland. “This type of headache is usually described as an aching dull pressure throughout the head, or like a headband sensation around the head. For others, dehydration is a very common trigger for migraine headaches, which are one-sided, severe, throbbing headaches with nausea and sensitivity to light and sound.”

Indeed, according to a 2021 review in Current Pain and Headache Reports, dehydration headaches are what’s known as secondary headaches. That means they are not characterized as a “headache syndrome,” like migraines or tension headaches, but that dehydration can contribute to or worsen symptoms in people with other types of headaches. For this reason, and because there are different levels of dehydration, there is not much data on the frequency of dehydration headaches. 

One thing that is clear: Dehydration makes headaches worse. In a 2020 study of more than 250 women with migraine, published in the Journal of Clinical Neuroscience, those who drank more water and had a higher total fluid intake had reduced severity, duration, and frequency of migraine attacks compared to those who drank less.

In addition to the headache, someone with a headache from dehydration would likely experience other symptoms of dehydration or signs that your body is lacking in or conserving water, says Dr. Siwek. These might include:

• A strong sensation of thirst 
• Dark yellow urine or decreased urine output
• Dry, sticky mouth and skin
• Fatigue 
• Dizziness or lightheadedness
• Increased heart rate

How do I know if I have a dehydration headache?

There is one obvious way to know if you have a headache brought on by dehydration. “A clue is often that the headaches come on after extended periods in hot temperatures or physical activity where you are losing a lot of water from sweating,” Dr. Baron says. In these instances, it’s easy to make the correlation between water loss and the immediate arrival of headache symptoms. 

That said, the connection won’t always be this cut and dried. “People may not always immediately recognize dehydration as the cause of their headaches,” Dr. Siwek says. “Chronic headaches can have various triggers, and it may take some time to identify dehydration as a potential factor.”

If you’re having chronic headaches that you’re unable to handle or treat on your own or the strategies you’re using are not working, it’s worth seeking out a headache or pain specialist for medical advice. In these cases, chances are that there are multiple factors contributing to your headaches that need to be addressed.

How do I manage dehydration headaches? 

If your first instinct is that drinking more water is the key to managing and getting rid of dehydration headaches, you’d be spot on. “Drinking water is the primary and most effective solution,” Dr. Siwek says. “It may take some time for the headache to subside after rehydration, but improvement should occur relatively quickly.”

Exactly how much water do you need to drink? “The amount of water needed can vary based on factors like age, weight, and activity level,” notes Dr. Siwek. Also, if you’ve been regularly skimping on water intake, it may take some time to rehydrate your body to the levels needed to banish your headache. When it comes to adequate water intake, it’s a marathon, not a sprint. “Once the headache comes on, that means it is time to start rehydrating with water, but you do not want to drink all the water you’re behind on at one time,” says Dr. Baron. “It should be spread out over the day.”

Why? You want to give your body the time it needs to absorb and use the water. Rarely, if you drink too much water too fast, it can cause a condition called water intoxication, or water toxicity, which can be dangerous. To properly rehydrate and stay ahead of dehydration headaches, Dr. Baron suggests aiming to drink half your body weight in ounces of water each day and take small sips over a period of time when you’re rehydrating. You’ll also want to drink more on days when you’ll be sweating a lot or spending time in hot weather.

Not drinking enough water can lead to dehydration and imbalances in electrolyte levels or levels of essential minerals like sodium, potassium, and magnesium. Electrolyte imbalances can cause problems like fatigue, lethargy, and muscle weakness, all of which may contribute to headache symptoms. 

A 2023 study in Physiology confirmed that people with migraine are particularly sensitive to electrolyte imbalances, which is why Dr. Siwek recommends sipping an electrolyte drink to restore the balance. There are store-bought sports drinks and Pedialyte powders that you can add to water, or you can mix a pinch of sea salt or Himalayan pink salt into your water. 

“Non-prescription pain medications like ibuprofen or acetaminophen may also provide relief,” Dr. Siwek adds. Over-the-counter pain relievers should be sufficient to help most dehydration headaches.

How do I prevent dehydration headaches?

Once you know that dehydration may be contributing to your headaches, it’s easy to avoid it in the future. Here are some of the easiest expert-approved ways to decrease your risk of dehydration headaches.

• Focus on hydration. Drinking an adequate amount of water throughout the day, every day, is crucial. Make sure to up your intake on particularly hot days, days with increased physical activity, or if you have fluid loss because of an illness.
• Monitor your urine color. This is a good indicator of how well-hydrated you are, notes Dr. Siwek. Look for a light yellow or pale straw color; if you have dark-colored urine, refill your water bottle. 
• Limit caffeine and alcohol intake. “Both can contribute to dehydration,” Dr. Siwek says. That said, caffeine withdrawal is also a common headache trigger for many people. If you’re one of them, make sure to compensate for your caffeine consumption by upping your water intake. 
• Eat water-rich foods. Fruits and vegetables that have a high water content, such as watermelon, honeydew, pineapple, celery, cucumber, and bell peppers, can count toward your daily fluid intake and help you avoid dehydration headaches. 

Then, if you’re still having headaches, it’s time to consult with a healthcare provider to rule out other health conditions that could be causing your symptoms.

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