You no longer have a headache, or pain located at a particular site: you are literally plunged into the pain, like in a swimming pool. There is only one thing that remains of you: your agitated lucidity and the pain that invades everything, takes everything. There is nothing but pain. At that point, you would give everything, including your head, your own life, to make it stop.

• Yves, cluster headache patient from France (from Rossi et al., 2018)

Key takeaways

• Cluster headaches are often considered among the most painful conditions known to medicine, if not the most painful (Nesbitt & Goadsby, 2012). Patients describe the pain as “devilish”, “grueling”, “unbearable” or “so violent that it is utterly intolerable” (Torelli & Manzoni, 2003), and rate it as significantly more painful than labor pain, gunshot wounds, or fractured bones, among others (Burish et al., 2021).
• Approximately 1 in 1,000 people worldwide will experience the excruciating pain of cluster headaches during their lifetime (Schindler & Burish, 2022). In any given year, 1.5 million to 5.6 million (median: 3.0 million) adults are affected.
• We aggregated statistical data from a couple dozen papers on the prevalence, frequency, duration, and intensity of cluster headaches to estimate their global pain burden.
• We estimate that all cluster headache patients worldwide spend ~74,200 person-years per year in pain at any intensity, of which ~46,200 are spent at ≥7/10 pain and ~13,600 at ≥9/10 pain—that’s nearly 5 million person-days of extreme suffering (≥9/10 pain) annually.
• Drawing from research on the heavy-tailed nature of pain intensity (Gómez-Emilsson & Percy, 2023), our numerical simulations show one way in which a straightforward aggregationist calculation means cluster headaches become a top global health priority. In particular, we compare the burden of cluster headaches with that of migraine, which is the 4th largest source of Years Lived with Disability (YLD) worldwide and 19th largest source of DALY (GBD, 2024).
• You can access the full simulations here: cluster-headaches.streamlit.app
• The fact that the prevalence of cluster headaches is much lower than that of other major diseases is actually advantageous and presents an attractive opportunity: we can get rid of a significant proportion of the most extreme human suffering worldwide at a small fraction of the cost of addressing more prevalent conditions.
• Philanthropists, donors, charity and tech entrepreneurs, policymakers, and other decision-makers should consider cluster headache relief a strong contender for directing their altruistic efforts. This is particularly true for individuals who care about alleviating the most extreme forms of suffering, but the case can be compelling from nearly any ethical perspective.