Can a Headache be Caused by Dehydration? Headaches FAQ

Fact checked by Olga Sadouskaya, MD
Clinical Pharmacologist, Chief Medical Officer

A headache is a pain in the head caused by the dilation of cerebral arteries, muscle contractions, or a reaction to drugs. Headaches are one of the most widespread and disabling conditions worldwide. Approximately 16 percent of the world’s population experiences headaches daily. They vary from harmlessly mild to discomforting to severely fatal. There are various types of headaches, each with its own characteristics.

Headaches could start suddenly or gradually and may be chronic or short lived. They could be:

  • Migraine headaches: These are the most predominant among women and usually affecting one side of the head. They may be preceded by visual disturbances known as auras or associated with lightheadedness and light sensitivity. Typical triggers include stress, hormones, and weather changes.
  • Tension headaches: Tension headaches classically present as a dull ache on both sides of the head and are usually caused by stress or fatigue.
  • Cluster headaches: Cluster headaches are frequent among men and occur periodically. They are usually localized around one eye and associated with smoking and alcohol consumption.
  • Sinus headaches: Inflammation of the sinuses within the skull can cause fever and pain. Sinus headaches may also be associated with allergies.

Can a headache be caused by dehydration?

Your body needs proper fluid maintenance to function optimally. When you do not take in enough water, you can be more predisposed to dehydration headaches. This type of headache occurs when you have been losing more fluid and electrolytes from your body than you have been taking in.

Dehydration causes the brain to shrink temporarily to compensate for fluid loss. This shrinking causes small veins and nerve fibers to stretch, leading to a headache. This pain may be very intense and debilitating. It could also be mild to negligible, depending on the fluid loss causing it.

Can you have a headache from eating ice cream?

Eating very cold substances like ice cream can trigger what is commonly known as brain freeze or a cold stimulus headache. A brain freeze affects the front or both sides of the head. It occurs when an icy substance touches the back of your throat or the roof of your mouth as you try to swallow. This headache does not persist for long, typically disappearing within five minutes.

Bowls of ice cream as one of the triggers for headaches

The pain caused by eating ice cream can be explained by the dilatation and constriction of tiny blood vessels within the throat. When your cold ice cream touches the mucosa of your throat, it causes the small blood vessels within that area to rapidly narrow. This constriction is short lived, and the vessels dilate very quickly right after. This rapid change activates the nerve fibers responsible for transmitting pain sensations around the head. The brain interprets this constriction and expansion of these tiny blood vessels as pain.

Considerable research has shown that headaches associated with cold substances like ice cream are more common among people with migraines and cluster headaches. However, this does not imply that you cannot experience cold stimulus headaches if you do not have migraine headaches. So, if you experience this form of headache after a cold bowl of ice cream, that doesn’t necessarily mean a migraine is on its way. You can prevent this headache by eating your ice cream slowly or curling and pressing the underside of your tongue to the roof of your mouth.

Can a headache cause nausea?

Nausea is the uneasy feeling of queasiness associated with an unpleasant urge to vomit. It is a feeling commonly associated with problems in the neurological system, including headaches. Nausea may be accompanied by dizziness, vision disturbances, and varying levels of discomfort.

Dehydration is one of the most common causes of headaches with nausea.

Nausea can also result from increased intracranial pressure. Pressure within the skull can be increased by a growth, fluid, or blood collecting there as a result of an injury.

There are different types of headaches, and each can cause nausea differently. Migraines have been associated with elevated brain serotonin levels. Serotonin is an important neurotransmitter that acts on the gut and vomiting centers of the brain. The feeling of nausea commonly preceding vomiting is believed to occur when serotonin accumulates in the gut.

The mechanism by which dehydration causes nausea is not so precise. However, the urge to vomit is primarily associated with forms of dehydration that are severe enough to reduce blood flow. Some research reports suggest that reduced blood flow in critical brain areas like the area postrema may be responsible for nausea experienced during severe dehydration. In extreme cases, nausea may be followed by vomiting, which worsens dehydration and starts a vicious cycle.

Can a headache cause dizziness?

Dizziness is the general term to describe a spectrum of abnormal sensations associated with the ear’s vestibular system. These strange sensations include vertigo, disequilibrium, presyncope, and lightheadedness. Many bouts of vertigo are caused by crystals in your inner ear that come loose. Some other forms of dizziness are associated with severe throbbing headaches, such as migraines. People with migraine headaches are about three times more likely to experience dizziness than the general population.

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It has been recognized for over a century that there is probably a link between migraines and dizziness. Dizziness associated with migraine headaches may be caused by the neurochemical and blood flow changes in your cerebral cortex or brainstem. These changes may disrupt signals that relay information from the vestibular or sensory system in your inner ear, causing dizziness, nausea, and vomiting, among other symptoms.

Headaches associated with dizziness may also result from brain infections like meningitis or encephalitis. The type of dizziness related to headaches usually resolves with the treatment of the headache itself. Therefore, you may need to consult a doctor for further evaluation if you experience dizziness during headaches.

Does caffeine help a headache?

Caffeine may relieve headaches or make the pain worse, depending on the time of consumption. During a headache, there is an increase in the circulation of blood to surrounding pain nerve fibers. Caffeine helps with headaches in different ways.

Caffeine has some properties that help to narrow the blood vessels supplying the structures around your brain. Vascular constriction reduces blood flow around the nerve fibers that send pain signals to the brain. This process ultimately helps to relieve headaches naturally. Caffeine has also been credited with helping the absorption of regular painkillers like aspirin and acetaminophen.

Three cups of coffee to represent the idea that caffeine can help a headache

Headaches may be caused by decreased blood flow to the brain. In some cases, moderate concentrations of caffeine can cause vasodilatation and relieve mild to moderate headaches. A small amount of caffeine can help to alleviate your headache, but heavy or continuous consumption might be debilitating. You may constantly feel lightheaded with visual problems and an inability to sleep. These in themselves can also lead to nasty headaches. It is, therefore, best to consume caffeine in moderation and avoid becoming dependent on it to maintain a balance.

Can a headache be a sign of pregnancy?

Headaches can sometimes be an early sign of pregnancy. A clinical report found that approximately 40 percent of pregnant women experience headaches, usually resulting from hormonal changes during pregnancy. You may experience varying degrees of throbbing pain, which often gets better as the pregnancy progresses.

Pregnancy headaches may also point to stress, dehydration, or low blood sugar. It could also result from dangerously high blood pressure in conditions known as pre-eclampsia and eclampsia. These headaches are often throbbing, limited to one side of the head, with increased sensitivity to light and noise.

If you experience persistent headaches during pregnancy, you should consult your doctor to determine the appropriate line of care to ensure the safety of both you and your baby.

Medications to help control your headaches associated with pregnancy may be prescribed, depending on the other symptoms that you are also having alongside the headaches.

Getting enough sleep and engaging in some relaxing activities can help you cope with pregnancy headaches. Make sure to stay hydrated by drinking lots of fluids. Some painkillers may be harmful to use for your headache during pregnancy. Therefore, see your doctor for advice about the appropriate painkillers for your headaches.

What should you do when your headache is serious?

You can consider a headache severe when it is characterized by one or more of the following:

- Starts suddenly and is very severe

- Recurs more often than usual

- Persists for longer than normal

- Becomes constant

- Interferes with sleep

- Prevents you from concentrating

- Interferes with your daily activities

- Progressively worsens

- Doesn’t respond to pain medications

- Worsens with a change in position

- Is accompanied by any of the following:

  • Nausea
  • Vomiting
  • Visual disturbances
  • Dizziness
  • Fainting
  • Fever
  • Neck stiffness
  • Speech problems like slurring
  • Hearing problems like tinnitus or reduced hearing
  • Problems with body movement
  • Body weakness
  • Seizures
  • Head trauma

Contact your doctor immediately if you experience any of the above symptoms with your headache. Prompt medical intervention may be necessary to avoid fatal complications. Your doctor will evaluate your symptoms, identify the underlying cause of your headache, and suggest appropriate treatment.

December 21, 2022