Each week, MyHealthNewsDaily asks the experts to answer questions about your health.
This week, we asked neurologists and headache specialists: Does caffeine cause headaches, or cure them?
Laura M. Juliano, director of Behavioral Pharmacology and Health Promotion at American University, Washington, DC:
"There have been some case reports of people experiencing headache after drinking caffeine, but in general caffeine does not directly cause headaches.
"Regular caffeine consumption leads to physical dependence on caffeine, which manifests as withdrawal symptoms when a caffeine user abruptly stops using caffeine. A diffuse throbbing headache is a hallmark feature of caffeine withdrawal. The reason for this is that one of the pharmacological effects of caffeine is a constriction of blood vessels in the brain.
"When someone regularly drinks caffeine, the body adjusts in essence fighting this effect. Then when caffeine isn't consumed the result is that blood vessels dilate too much, which causes a headache. It takes a little while for the body to readjust to not having caffeine and that is why caffeine withdrawal headaches can persist for a week or more. A person doesn't have to be a very heavy caffeine user to experience a caffeine withdrawal headache. It varies from person to person but even as little as a small cup of coffee (100 mg of caffeine) each day could lead to withdrawal if someone stops caffeine abruptly.
"Caffeine can cure headaches that are caused by caffeine withdrawal. In fact, most people experiencing a caffeine withdrawal headache will feel better within 30 to 60 minutes of consuming caffeine. Caffeine is also added to some over-the-counter and prescription headache medications because there is some evidence that it enhances the effectiveness of analgesics (medications for pain).
"If someone is headache-prone, they should avoid using caffeine regularly."
Dr. Kathleen Digre, fellow of the American Academy of Neurology and director of Headache and Neuro-ophthalmology Division at the University of Utah in Salt Lake:
"The thing about caffeine and headache is that's it's complex, because it's both. Caffeine can be useful for the onset of headaches when taken with pain medications.
"There are certain headaches, called hypnic headaches, that can be prevented with caffeine. Hypnic headaches are a rare headache seen in elderly individuals that starts after they fall asleep. Drinking a bit of coffee before you go to sleep can prevent hypnic headaches. Caffeine is also used in post-lumbar puncture headaches [which can occur after a person undergoes a spinal tap].
"For other types of headaches, sometimes caffeine is a cure when it's put in combination with many pain medicines such as acetaminophen, aspirin, ibuprofen, indomethacin and ergotamine. Caffeine increases the strength of the medication and how quickly it works.
"But caffeine is a two-edged sword. The other side of the coin is if you take a lot of caffeine and then stop it, you can have a withdrawal headache. A lot of people drink coffee during the week, and then don't have it on the weekends, and they get a headache.
"If you take caffeine every day, especially with the medications to stop a headache, it can give people severe chronic rebound or medication-overuse headaches.
"While many people believe caffeine cures headaches because it is a vasoconstrictor, caffeine has minimal vasoconstrictive properties; it's ability to help headaches is related to its complex properties in the pain pathways. It is not just due to a vasoconstriction that's an oversimplification."
Dr. Joseph Kass, assistant professor of Neurology at Baylor College of Medicine and Chief of Neurology Service at Ben Taub General Hospital in Houston:
"The jury is mixed on that. We know that a number of over-the-counter and prescription medications have caffeine for the purpose of making them more effective. Caffeine speeds up the absorption of the medication and it reduces the dose you may need to get pain relief.
"On the flip side, studies have shown that caffeine from tea and coffee can cause rebound headaches.
"Recent studies looking at people who had chronic daily headache, and people who had occasional migraine headaches that turn into daily headaches, found an association with caffeine. One of these correlations among people who had chronic headaches and analgesic overuse. But daily use of caffeine was another association. Even people with chronic post traumatic headaches (headaches that follow a head injury) there was also an association with caffeine.
"The issue with caffeine is similar with any pain medicine: if you take it on a continual basis, especially together is medicine, you are at risk for developing rebound headaches. However, in 2009, there was a study from Norway that showed people who drink caffeine have less chance of developing headaches.
"Caffeine can also provide relief for a patient with a migraine. In moderation it has a lot of benefits, like anything else if you're using it excessively, [caffeine] can cause problems. We know that any pain medication that is used too frequently can contribute to headaches. If you're having migraines that are lasting more than a few days, or that are happening more than once a week, you should see a headache specialist."
Dr. Todd D. Rozen, director of the Geisinger Headache Center in Wilkes-Barre and Danville Penn
"Caffeine can both cause and cure headaches.
"Caffeine actually can be helpful for headaches if it is used at the time of a headache for example, in combination [medicines] like Excedrin or even just as a strong cup of coffee. In this setting, caffeine works in several ways.
"First, as it constricts cranial blood vessels, it can alleviate pain ... especially in migraine headaches where there is vessel dilation. In addition, when caffeine is taken at the time of another medication, for example when used with an anti-inflammatory, it will enhance the absorption of that other medication.
"It may also have effects on neurotransmitters involved in head pain but there is not much data on this.
"Caffeine can also cause headaches when it used daily for long periods of time ... Caffeine is causing the person to have daily headache when it is used on a daily basis.
"Or caffeine can lead to a headache when it has been stopped after long periods of daily use, thus causing a substance withdrawal headache. A caffeine substance withdrawal very common cause of weekend headaches (if you miss that cup of morning Java), or fasting headaches like with The Jewish or Islamic fasting holidays.
"What I tell patients is that caffeine can be very helpful for headaches if used intermittently. And if you have no medication around for your headache, take a strong cup of coffee, and that typically will help the pain. Daily caffeine intake, however, either in the form of combination analgesics or coffee, soda, energy drinks (especially high amounts every day) can lead to a daily headache and a severe withdrawal headache once it has been stopped."
Dr. Randolph W. Evans, clinical professor of Neurology at Baylor College of Medicine in Houston:
"Caffeine alone or combined with other drugs can relieve tension-type and migraine headaches in some people, by blocking adenosine receptors and blood vessels which result in the release of excitatory [brain chemicals called] neurotransmitters, and constriction of blood vessels in the brain.
"People are generally aware that caffeine is found in coffee, tea, soft drinks and chocolate, but may not know that caffeine is also contained in a variety of over the counter medications such as Excedrin and Anacin, and prescription drugs as butalbital combinations (such as Fiorinal and Esgic) contain caffeine.
"As an example, an eight ounce cup of brewed coffee contains 135 mg caffeine, eight ounces of Lipton tea has 35-40 mg, 12 ounces of Coca-Cola has 45 mg, and Excedrin (and Excedrin migraine, which have the same ingredients) contains 65 mg.
"About 50 percent of people who consume more than 200 mg of caffeine daily may develop caffeine withdrawal headaches when they suddenly stop caffeine, which can also be associated with nausea, depression and flu-like symptoms. Some people are quite sensitive, and can have withdrawal even after regular consumption of 100 mg daily.
"So enjoy the stimulating and pain relieving properties of caffeine in moderation. However, too much caffeine can not only make you wired but can also cause or worsen pre-existing headaches. In addition, women should consume caffeine with caution during pregnancy, in consultation with their obstetrician, as consumption of 200 mg daily or more may increase the risk of miscarriage."