Quick answer
No randomized controlled trial has tested cannabis for cluster headache. Evidence is limited to small surveys, case reports, and patient reports. The American Headache Society states that evidence is not sufficient to recommend cannabinoids for headache disorders. High-flow oxygen and subcutaneous sumatriptan have trial data and remain first-line acute treatments.
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What cluster headache is
Cluster headache is a primary headache disorder. Prevalence is about 1 in 1,000 people. Attacks are severe and one-sided, sited around the eye, above the eye, or at the temple. An untreated attack lasts 15 to 180 minutes. Frequency ranges from one attack every other day to 8 attacks per day.
Attacks include at least one autonomic sign on the same side: red or tearing eye, drooping eyelid, runny or blocked nose, sweating, or a sense of ear fullness. Most patients cannot stay still during an attack.
About 85 to 90 percent of patients have the episodic form. Bouts last weeks to months, separated by remissions of 3 months or more. The rest have the chronic form, defined as no remission for 12 months, or remissions shorter than 3 months.
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What the evidence on cannabis shows
Data on cannabis for cluster headache come from surveys and case reports, not controlled trials. Survey studies report that a share of patients try cannabis for attacks. Reported effects range from no change to a drop in attack frequency. Sample sizes are small, answers rely on memory, and there is no placebo group.
Some patients report relief during an attack. Others report no effect on pain, or an effect only on the restlessness and anxiety that come with an attack.
Psychedelics are a separate research line. Small surveys of psilocybin and LSD use in cluster headache report lower attack frequency. That evidence is also uncontrolled. It is not evidence about cannabis.
Treatments with trial data
- High-flow oxygen: 100 percent oxygen at 12 liters per minute through a non-rebreather mask for 15 to 20 minutes. Relief in about 70 percent of attacks, often within 15 minutes.
- Sumatriptan 6 mg under the skin: relief in about 75 percent of patients within 15 minutes. Not for people with heart disease or uncontrolled high blood pressure.
- Zolmitriptan 5 mg nasal spray: an option when injections are not available.
- Verapamil: preventive drug, 240 to 960 mg per day. Needs ECG checks at baseline and after dose changes.
- Galcanezumab: FDA approved in 2019 for episodic cluster headache. 300 mg monthly.
- A short course of prednisone or a greater occipital nerve block: transitional treatment while a preventive takes effect.
Practical points for patients
- Route matters. Inhaled or vaporized cannabis takes effect in 2 to 10 minutes. Edibles take 30 to 120 minutes. A cluster attack can end before an edible takes effect.
- No standard dose exists for cluster headache. Flower THC content runs about 15 to 25 percent. Concentrates can pass 80 percent.
- Frequent use can cause medication overuse headache and cannabis use disorder. Daily use raises both risks.
- Alcohol triggers attacks in many patients during a bout, often within 1 hour of drinking. Nitroglycerin does the same.
- Smoking rates in cluster headache clinic samples are higher than in the general population. Smoked cannabis adds smoke exposure.
- Tell your neurologist about cannabis use. It affects decisions about verapamil, triptans, and monitoring.
State medical cannabis programs
Cluster headache is not a qualifying condition in most state medical cannabis programs. State lists include cancer, HIV/AIDS, epilepsy, multiple sclerosis, Crohn's disease, glaucoma, and post-traumatic stress disorder. A few states let a physician certify any condition they judge debilitating. Check your state program for the current list.
Open questions
Three questions have no answers from trials: which cannabinoid, at what dose, and by which route. CBD alone has no trial data in cluster headache. There is also no data on how cannabis interacts with verapamil or galcanezumab in this group.