A migraine is a neurological condition characterized by recurring attacks of moderate to severe throbbing pain, often localized to one side of the head. These attacks are typically accompanied by symptoms like nausea, vomiting, and extreme sensitivity to light and sound. The relationship between cannabis and migraines is unusual, presenting a paradox for those seeking relief. Cannabis can act as either a trigger that initiates an attack or a therapeutic agent that provides pain relief. This dual nature means the effects are highly individualized, depending on the person, the method of consumption, and the specific chemical components involved.
Acute Effects: Cannabis as a Trigger
For some individuals, consuming cannabis can acutely trigger a headache or a full migraine attack. This immediate adverse reaction may be linked to the chemical composition of the product, particularly the concentration of tetrahydrocannabinol (THC). High doses of THC are associated with adverse reactions, potentially due to effects on the circulatory system.
The method of consumption can also be a factor in triggering head pain. Inhaling cannabis smoke can irritate the airways and lead to dehydration, both of which contribute to headaches. Furthermore, some specific compounds found in cannabis, such as certain terpenes, may act as vasoconstrictors or irritants in sensitive individuals.
The Role of the Endocannabinoid System
The underlying reason cannabis affects migraine pathology lies in its interaction with the body’s Endocannabinoid System (ECS). The ECS is a regulatory network composed of endocannabinoids, receptors, and enzymes that maintain biological balance, or homeostasis, across various systems, including those that process pain. The two main receptors are Cannabinoid Receptor 1 (CB1), found in the central nervous system, and Cannabinoid Receptor 2 (CB2), found mainly on immune cells in the periphery.
Cannabinoids from the cannabis plant, such as THC and cannabidiol (CBD), act on these receptors to modulate pain signaling. THC primarily activates both CB1 and CB2 receptors, which can dampen the release of neurotransmitters involved in transmitting pain signals. CBD works through complex pathways, including some that reduce neuroinflammation, a significant component of migraine attacks.
This system is relevant because some research suggests that headache disorders may be linked to “Clinical Endocannabinoid Deficiency” (CECD). People with chronic migraine have been observed to have lower circulating levels of endocannabinoids, specifically anandamide (AEA). Introducing external cannabinoids may help correct this deficiency, stabilizing the system and reducing the frequency of migraine attacks. Cannabinoids also influence the trigeminovascular system, where they inhibit the release of calcitonin gene-related peptide (CGRP), a pain-signaling molecule implicated in migraine.
Therapeutic Use for Migraine Management
Historical reports suggest that cannabis has been used for hundreds of years to manage headaches, with some physicians endorsing its use for migraine. Today, many people with migraine self-medicate with cannabis for both acute relief and prophylactic purposes. For acute relief, inhaled forms of cannabis are often preferred to stop a migraine in progress, as they allow for rapid delivery of cannabinoids to the brain.
For prophylactic use, a combination of THC and CBD, often taken daily, has been reported to reduce the frequency of monthly migraine attacks in some patients. A study found that an oral dose of 200 milligrams of a THC and CBD combination was associated with a 55% decline in migraine pain. While anecdotal evidence is promising, high-quality, randomized controlled trials are still limited. The optimal ratio of THC to CBD and the most effective delivery method remain subjects of ongoing research.
Headaches Related to Cessation and Overuse
Paradoxically, the frequent use of cannabis to treat headaches can lead to a condition known as “medication overuse headache” (MOH), also called a rebound headache. This occurs when the brain adapts to the constant presence of the drug, and when the effect wears off, the body triggers a headache as a form of withdrawal. Studies have shown that people with chronic migraine who use cannabis are significantly more likely to have MOH compared to non-users.
The risk of developing MOH increases with chronic, heavy use, and the headache typically resolves only after discontinuing the overused medication. Headaches can also emerge as a symptom of Cannabis Withdrawal Syndrome when a person suddenly stops using the substance after prolonged, regular consumption. This withdrawal headache is part of a cluster of symptoms, including irritability and sleep disturbances, that occur as the body adjusts to the absence of external cannabinoids. These cessation and overuse phenomena highlight that, like many acute pain medications, cannabis is not immune to the risk of exacerbating the very condition it is used to treat.