Dehydration is a common trigger for migraines, but how does it happen, and what can we do to prevent it?

Dehydration occurs when the body loses more liquid than it takes in. We have to consider what gets in, what gets out and the body mechanisms that regulate all this! 

Is dehydration only about water?

There is no free water in the body. It is always mixed with other things like cells, ions (sodium, potassium) and other chemical substances, glucose being an important one.  Bodily fluids are «solutions» that can be more or less «concentrated». Remember chemistry class? In particular, our body needs to have a good balance between salt and water. If you don’t have enough salt, you won’t keep water and develop low blood pressure. If you eat tons of salt, you will develop fluid retention. So it is not only about the volume of water but also what is in it. 

Why is it better to drink water instead of juice to hydrate?

When we drink, it’s not only important to think about the water, but also about what else is in what we drink! Drinking pure water is the best. Other beverages may contain things (we call them «osmoles») that are already «filling» the water. The more osmoles a beverage contains, the less hydrating it will be. Some drinks that are higher in osmoles include:

  • Juice or soda with sugar
  • Any alcoholic beverage 
  • Salty broths

Sodas are really bad for our health as they contain tons of sugar, artificial colours, they are acidic and the low-calorie version contain aspartame that some people report as a migraine trigger. Artificial sweeteners keep your cravings for sugar active, which can lead to weight gain. 

How do we lose body water?

There are many ways for water to leave our bodies, and situations that can lead to dehydration: 

  • Urine: diuretics (substances that make us pee) can be medications but also beverages like alcohol and caffeine
  • Sweat: if it’s hot and dry or if you exercise (or both)
  • Breath (yes, we are «drying inside our lungs»): also, if it’s hot and if you exercise, if the air is very dry
  • Diarrhea and vomiting: may occur during a migraine (another difficult symptom of migraine attacks). 
  • Secretions like mucus (if one has a big cold for example)

Why would dehydration trigger migraines?

We are not yet sure why dehydration can trigger migraine. The water / ion / osmole balance in the brain is very important, as it allows a proper electrical function. Some researchers believe that when the osmolarity of the brain increases (the water becomes too concentrated), some receptors may be activated, causing a migraine.

Follow these tips to ensure you stay hydrated every day:

Eat hydrating foods

  • Fresh raw vegetables, especially cucumbers, spinach, lettuce, zucchini, bell peppers, carrots, and celery
  • Fresh fruit (keep an eye on the sugar content)
  • Broths and soups (keep an eye on the salt / water balance though)

Drink plenty of

  • Fresh water—add lemon, cucumber or mint if plain water doesn’t suit you
  • Electrolyte-rich beverages like coconut water
  • Herbal teas (chamomile, peppermint, rose, etc.)

How much should I drink exactly?

There is no unique answer to this. It is not always easy to determine as the needed amount depends on your weight, sex, genetics, diet, medications, activities, weather, the dryness of the air, salt intake… A good rule of thumb is to drink about 2 litres of fresh water daily, that’s one cup every 2 hours if you’re awake 16 hours.  

Overall, most people don’t drink enough water and drink too much juice and caffeine (and alcohol). Adding a few cups of water or herbal teas to your routine is a good start. Making sure to drink every 2-3 hours is also a good way of remembering. 

More tips to stay hydrated

  • Carry a reusable water bottle in your bag or purse
  • Stay inside or in the shade during the hottest part of the day in the summer (12pm-4pm)
  • Drink plenty of water before and during workouts
  • Try not to let yourself get thirsty by sipping water throughout the day
  • Avoid excessive consumption of diuretics (foods/beverages that increase the production of urine), such as coffee, black and green tea, cola, alcohol, some herbal teas (dandelion, hibiscus, hawthorn)
  • Avoid sugary drinks like fruit juice and soda

Will better hydration cure my migraines? 

Probably not…but it could decrease the frequency of attacks, especially if you come to realize that you have «dehydrating habits». Remember, dehydration is not «the cause» of migraine. It is a trigger that can be safely and easily managed. 

Drinking water is healthy, safe, costs nothing…so why not give it a try! 


Martins IP, Gouveia RG. More on water and migraine. Cephalalgia. 2007;27(4):372-4.

Spigt MG et al. Increasing the daily water intake for the prophylactic treatment of headache: a pilot trial. Eur J Neurol. 2005;12(9):715-8.

Blau JN. Water deprivation: a new migraine precipitant. Headache. 2005;45(6):757-9.


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