Dear Doctors: I am experiencing extreme headaches about 15 minutes after smoking cannabis. It used to happen occasionally, but now it's every time. The migraine, which is very intense, goes away after about 30 minutes. Can you help me understand this?
Dear Reader: The specifics of your question fall outside of our normal practice. However, we were able to consult with colleagues here at UCLA who are experts in the area of headache and migraine. They pointed us to a phenomenon known as reversible cerebral vasoconstriction syndrome, or RCVS, which causes the symptoms you have described. Primary among them is the sudden onset of a severe and debilitating headache. Due to the speed with which it reaches peak intensity, this is referred to as a “thunderclap headache.” Additional symptoms can include nausea, vomiting, sensitivity to light, blurred vision, muscle weakness and confusion.
RCVS is most often associated with the physical changes that occur during and after pregnancy. It can also be triggered by a range of substances. These include certain prescription medications, caffeine, nicotine, illicit drugs and, yes, cannabis. Recent medical literature shows that the legalization of recreational cannabis has been accompanied by a rise in case reports of serious complications involving blood flow to the brain. This includes a measurable increase in the diagnosis of RCVS associated with cannabis use.
The severe headache pain that occurs in RCVS is caused by the constriction of blood vessels in the brain. In some cases, the reduction of blood flow to the tissues of the brain can cause a stroke. That makes RCVS a serious condition and a medical emergency. Anyone experiencing these symptoms, whether or not they are associated with cannabis use, should seek immediate medical attention.
A thunderclap headache can be a warning sign of a life-threatening condition. These include severely high blood pressure, bleeding in the brain, a breach in one of the arteries in the neck and viral or bacterial meningitis.
Diagnosis includes a physical exam, medical history, family history and information about the use of any medications or drugs. Imaging scans may be used to visualize the areas of the brain affected by the constricted blood vessels. In order to identify potential underlying causes, tests to assess blood flow and kidney and liver function may be requested.
Treatment focuses on supportive care and is tailored to each specific case. It can include intravenous fluids, migraine medication, calcium channel blockers to relax the blood vessels and medications to manage blood pressure.
Although many states have legalized the recreational use of cannabis, it remains a Schedule 1 controlled substance under federal law. This overrides state regulations. Other than for a handful of FDA-approved prescription medications with very specific uses, cannabis remains illegal in the United States. This legal limbo has placed significant constraints on evidence-based research into its potential health effects.
This knowledge gap is further complicated by the fact that new strains of cannabis grow increasingly more potent. In light of your symptoms, which are quite serious, we urge you to take a break from cannabis and to see your health care provider as soon as possible.
(Send your questions to [email protected], or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10960 Wilshire Blvd., Suite 1955, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)
