A dehydration headache happens when your body is dehydrated (doesn’t get the fluids it needs). Headache pain often appears along with other symptoms of dehydration, including dizziness, extreme thirst and dry mouth. Pain usually goes away after drinking water, resting and taking pain relief medication.
A dehydration-related headache happens when your body doesn’t get enough fluids. Even mild dehydration can cause a headache. Usually, other symptoms of dehydration (such as fatigue, dizziness, extreme thirst and dry mouth) appear along with headache pain.
Dehydration headaches often get better with at-home remedies like drinking water, resting and taking over-the-counter pain relievers. If you have signs of severe dehydration (such as confusion or dizziness), get medical help right away.
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Healthcare providers aren’t sure how many people get dehydration headaches. In the United States, most people don’t get enough fluids, either from their food or by drinking water. Lack of fluids can lead to dehydration, which causes headaches. Babies, young children and older adults have a higher risk of dehydration. People with certain health conditions (such as diabetes) also have an increased risk.
Pain from a dehydration headache can range from mild to severe. You may feel pain all over your head or in just one spot, such as the back, front or side. The pain is usually like a dull ache, but it can also be sharp.
You may have a throbbing (pounding) headache, or the pain might be constant. The pain might get worse when you bend over, shake your head or move around.
Other dehydration symptoms usually occur along with headache pain. These include:
Your body is mostly made of water. It’s in your blood, organs, soft tissues and bones. When you sweat and urinate, your body loses fluids and electrolytes. Electrolytes are minerals that help your body work like it should.
Dehydration happens when the amount of fluid that’s leaving your body (in sweat and urine) is more than the amount of fluid you’re taking in. Dehydration can be dangerous because it means your body isn’t getting the fluids it needs.
Dehydration can result from:
When you’re dehydrated, your brain and other tissues in your body shrink (contract). As your brain shrinks, it pulls away from the skull, puts pressure on nerves and causes pain.
Even mild dehydration can lead to a headache. When you drink water and other fluids, the brain plumps up to its previous size and the pain goes away.
Dehydration headaches are secondary headaches because providers know what causes them. You probably have a dehydration headache if:
If your headache doesn’t get better after drinking water and resting, see your provider for a checkup. Another condition or illness may be causing your headache. Your provider may order imaging studies (like an MRI or CT scan) to see pictures of your brain and determine what’s causing the pain.
Most dehydration headaches get better in a few hours with at-home treatments. To relieve pain from a dehydration headache, you should try headache remedies such as:
People who are very dehydrated may need additional care. Some people may need to stay in the hospital while they’re recovering. Healthcare providers treat severe dehydration with IV fluids (through a vein in the arm).
The best way to avoid a dehydration headache is to stay hydrated. To prevent dehydration, you should:
Most dehydration headaches get better after drinking water and taking it easy for a while. If headaches keep happening, you may have chronic (long-term) dehydration. Chronic dehydration can lead to serious medical problems, including kidney stones and urinary tract infections (UTIs). People who aren’t hydrated have a higher risk of heat exhaustion and other heat illness.
Dehydration can trigger (cause) a migraine headache. If you get migraines, it’s essential to drink plenty of water. Staying hydrated may help you prevent a migraine attack.
See your healthcare provider if:
A note from Cleveland Clinic
Dehydration headaches can range from mildly annoying to severely painful. But they usually go away after drinking water and relaxing in a cool place. To prevent a dehydration headache, drink water throughout the day and increase the amount you drink when you exercise. Always stop and drink water if you feel symptoms of dehydration. If your headache doesn’t go away with water and rest, call your healthcare provider. Get help right away if you have a severe headache or if your pain comes back.
Last reviewed by a Cleveland Clinic medical professional on 12/03/2021.
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