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: Colleagues who are experts in the area of headache and migraine 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.
This is referred to as a “thunderclap headache.” Additional symptoms can include nausea, vomiting, sensitivity to light, blurred vision, muscle weakness and confusion.
RCVS most often is associated with the physical changes that occur during and after pregnancy. It also can be triggered by substances including certain prescription medications, caffeine, nicotine, illicit drugs and, yes, cannabis.
Recent medical literature shows the legalization of recreational cannabis has been accompanied by a rise in 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 brain can cause a stroke. That makes RCVS a serious condition and a medical emergency.
Anyone experiencing these symptoms should seek immediate medical attention.
A thunderclap headache can be a warning sign of a life-threatening condition such as 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 might be used to visualize the areas of the brain affected. To identify underlying causes, tests to assess blood flow and kidney and liver function might be requested.
Treatment focuses on supportive care and is tailored to each case. It can include intravenous fluids, migraine medication, calcium channel blockers to relax the blood vessels and medications to manage blood pressure.
Though Illinois and many other states have legalized the recreational use of cannabis, it remains a Schedule 1 controlled substance under federal law. This has placed significant constraints on evidence-based research into its potential health effects.
This knowledge gap is complicated by the fact that new strains of cannabis grow increasingly more potent.
Given your symptoms, which are quite serious, we urge you to take a break from cannabis and see your health care provider as soon as possible.
Dr. Eve Glazier and Dr. Elizabeth Ko are UCLA Health internists.
