One of the curiosities of cannabis is that it can lead to a range of responses in users. When it comes to headaches, some find that it alleviates pain, while others claim it exacerbates it. Anecdotes abound identifying cannabis as the culprit for kickstarting throbbing head pain. On the other hand, individuals who regularly experience headaches and migraines swear by weed to reduce the severity or frequency of their episodes.
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While individual and anecdotal experience is always valid, diving into scholarly research can offer a more expansive view of what's going on.
So, what does the research say about cannabis and headaches?
Evidence that cannabis helps with headaches
Evidence has been mounting over recent years indicating the utility of cannabis as a treatment for headaches. Conventional analgesics used to manage headache pain are not always effective. What's more, they can sometimes lead to more headaches — a condition known as medication overuse headaches.
A number of studies and surveys of human participants have presented findings indicating that cannabis may ease headache and migraine severity.
A July 2020 study published in the Journal of Integrative Medicine explored the efficacy of dried cannabis flower as a treatment for headache and migraine pain. Between 2016 and 2019, 699 participants engaged in the research, sharing details about the intensity of their symptoms and the dried cannabis flower they used to treat their pain. Changes in pain intensity were measured on a 0-10 scale both before and after consuming cannabis.
The authors found that 94% of participants experienced symptom relief within a two-hour period. The average reduction of symptoms was 3.3 points on a ten-point scale, with males experiencing greater relief than female users. Young users also experienced more significant relief than older users. Cannabis containing THC levels of 10% or higher appeared to offer more effective symptom relief for headache sufferers.
A June 2020 study published in the Journal of Pain investigated the effects of cannabis on headaches and migraines. The study used archival data from Strainprint, a medical cannabis app that enables patients to track symptoms before and after using cannabis. The study's authors analyzed data from 12,293 sessions where cannabis was used to treat headaches, and 7,441 sessions where it was used for migraines.
Cannabis reduced the symptoms in 89.9% of the headaches and 88.1% of the migraines. Similar to the study published in the Journal of Integrative Medicine, men were slightly more likely to experience a reduction in headache pain than women (90.9% vs 89.1%). Users reported a 47.3% decrease in headache severity and a 49.6% decrease in migraine severity. The study's authors found that neither cannabis strain nor cannabinoid concentration appeared to impact on therapeutic efficacy. While repeated cannabis use sometimes led to developing tolerance to its effects, cannabis didn't appear to lead to medication overuse headaches associated with conventional treatments.
For Rosemary Mazanet, M.D., Ph.D., and Chief Scientific Officer of Columbia Care, there is a general consensus among experts that cannabis may relieve pain. “There is evidence that migraine headaches may respond particularly well to cannabis, and the underlying endocannabinoid system may be involved in migraine headaches,” explains Mazanet. “And cannabis is known to help with nausea in general, which can accompany migraines.”
How might cannabis work on the body to ease headaches?
The body's serotonin system is a critical player in headaches and migraines. Low or fluctuating levels of serotonin are associated with headaches and migraines. Serotonin is also implicated in the body's endocannabinoid system. Anandamide, one of the two main endocannabinoids found in the body, potentiates serotonergic receptors. Low levels of anandamide can also cause headaches and migraines. In fact, researchers theorize that migraine is one of several symptoms caused by Clinical Endocannabinoid Deficiency syndrome.
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Evidence suggests that the dysregulation of the endocannabinoid system may result in headaches and migraines. Individuals who are deficient in anandamide may therefore benefit from cannabis medicine, as the cannabinoids in cannabis can mimic the body's endocannabinoids. Cannabinoids also demonstrate dopamine blocking and anti-inflammatory properties that may also be relevant in treating migraines.
However, other factors, such as stress or lack of sleep, can also contribute to headaches. In these cases, the efficacy of cannabis may rest in its ability to ease stress and induce sleep.
Preclinical research has helped us to understand one of the mechanisms that enable cannabis to provide migraine relief. The CB1 receptor is a therapeutic target for migraine. Delta-9 THC activates the CB1 receptor, reducing migraine-like pain when delivered at the appropriate dose and time. THC is critical to achieving this efficacy, because it has a high binding affinity with the CB1 receptor. CBD, which has less of an affinity for the receptor, is unlikely to provide much relief if consumed without THC.
“THC in cannabis acts on receptors in the nervous system to alleviate pain and result in relaxation and calm,” explains Mazanet. “CBD use can also result in a reduction in inflammation over time. These effects combined can help people manage their stress and improve their sleep — because poor sleep is a known cause of headaches — and thus relieves their headache pain.”
Evidence that cannabis can exacerbate headaches
However, the waters become muddied by claims that cannabis can also trigger or exacerbate headaches. The 2020 Journal of Pain study also found that in 2.4% of headache cases and 3.1% of migraine cases, cannabis exacerbated headache symptoms.
The 2017 study published in the Harm Reduction Journal also found that cannabis can lead to worsening headache symptoms or even trigger episodes. The authors surmised that factors such as timing, frequency of use, administration method, and dosage might be influential. They also pointed out certain cannabinoids and terpenes may ease headache pain, while others might exhibit opposing effects.
Headaches have also been associated with “weed hangovers.” Excessive consumption of cannabis sometimes results in what's colloquially known as a weed hangover the following day. Brain fog, groggy feelings, and headaches are commonly identified elements of the hangover.
Withdrawal after chronic cannabis use may also spur a headache. In a study of 469 frequent cannabis smokers published in Drug and Alcohol Dependence in 2010, 23.2% experienced headaches due to cannabis withdrawal.
According to Mazanet, sensitivity to certain cultivars may also incite headaches. “Some people are sensitive to THC strains that might cause them to experience anxiety, and that would not be a good thing for someone who had a headache to begin with,” says Mazanet. “People who know they are sensitive might want to try a hybrid product or one that contains CBD as well as THC.”
Bottom line
In general, the evidence points towards cannabis potentially being more helpful than harmful when it comes to headaches.
“There are many causes for headache, but the anxiety, muscle spasms, inflammation and other contributors to headache pain are usually reduced by cannabis, not provoked by it,” states Mazanet. That said, “deciding which cannabinoid to use for headaches is a very personal choice because people respond differently.”
As the studies show, there don't seem to be any hard and fast rules about which cannabinoids or ratios work best for headaches. Experimenting cautiously and responsibly with different cannabis strains to temper headaches may be critical to unlocking what works best for the individual. Cannabis products and cultivars with a healthy quantity of CBD can also help to minimize undesirable side effects like anxiety.
Major contributions from Dr. Adie Rae.