Chronic Migraine and Botox: Who the 15-Day Threshold Is For
OnabotulinumtoxinA is licensed for chronic migraine, defined as 15 or more headache days a month. What that definition means and why it is the gate.
The definition
Chronic migraine means 15 or more headache days per month, of which at least 8 have migraine features, sustained for more than three months. Fewer than 15 is episodic migraine — a different treatment pathway, not a lesser one.
Why the threshold exists
The licence follows the trials, and the trials enrolled a chronic migraine population. Below the threshold the evidence does not support the indication, so the number is a description of who was studied rather than a judgement about how much someone is suffering.
What the protocol involves
- 155 units across 31 fixed injection sites, head and neck
- Repeated every 12 weeks
- Effect is typically assessed after two cycles, not one
Counting days honestly
A headache day is any day with headache lasting four hours or more, or any day treated with acute medication regardless of duration. People routinely undercount, usually because a day that was managed successfully with an acute treatment does not feel like a headache day in retrospect. It is one.
If you are below the threshold
Episodic migraine has its own preventive options, including the oral CGRP antagonists and the anti-CGRP monoclonals. Not qualifying for this treatment is not the end of the pathway.