The honest answer is that the anesthetic wears off within hours, and the relief frequently does not. That gap between how long the drug lasts and how long the benefit lasts is the most confusing thing about this procedure, and it is also the most interesting thing about it.
Two different clocks
The local anesthetic itself is short-acting. Lidocaine gives a couple of hours; bupivacaine, which is longer-acting, gives several more. Numbness over the back of the head follows that same timeline and wears off with it.
The therapeutic effect runs on a separate clock. In a multicenter double-blind placebo-controlled trial in chronic migraine, patients given bupivacaine blocks went from 18.1 headache days a month to 8.8 after a month of weekly blocks, against 16.9 to 13.2 in the saline group.1 That is a benefit measured in weeks from an injection that stopped being pharmacologically active the same day.
Why relief outlasts the drug
The working explanation is that the greater occipital nerve feeds into the trigeminocervical complex, where sensory input from the neck and the head converges. Interrupting a stream of input into a sensitized system appears to let it settle, and it does not immediately re-sensitize when the anesthetic clears. This is a mechanism argument rather than a proven pathway, and it should be read as the current best explanation rather than a settled one.
What the range actually looks like
Duration varies widely between people, and it is not predictable in advance from the diagnosis, the severity, or how well the injection went. Broadly:
- Hours only. Relief that tracks the anesthetic exactly and then stops. Informative — it confirms the nerve is involved — but it is a diagnostic result more than a treatment.
- Days to a few weeks. The most common pattern.
- Months. Happens, and is more often reported when the underlying problem is occipital neuralgia or a cervicogenic pattern rather than migraine.
- Nothing at all. Also informative, provided the injection was guided. See why image guidance matters.
A caution about the averages
Meta-analyzes consistently find that occipital nerve block reduces pain intensity and the number of headache days.2,3 They also find it does not shorten the duration of an individual headache.2,3 Those are different outcomes, and it is worth being clear which one you are hoping for: this treatment tends to reduce how often and how badly, rather than how long any single attack runs.
How often it can be repeated
There is no fixed course and no magic number. The interval is set by how long the previous block held and by clinical need, not by a protocol. If a block gives six weeks, repeating at six weeks is reasonable. If it gives four days, repeating it on a schedule is the wrong response and the question becomes whether the target is right.
Where a steroid is added, that does place a practical limit on frequency — but the evidence that adding one helps at all is weaker than most people assume. See steroid or anesthetic.
Common questions
How long will my head feel numb?
Usually several hours, tracking the anesthetic. Numbness over the back of the head on the treated side is the expected result of blocking that nerve, not a complication — see what to expect.
My relief only lasted a day. Was it a failure?
Not necessarily. A short but complete response confirms the nerve is carrying the pain, which is useful information. It does mean a plain repeat is unlikely to be the answer — talk to us about what it points toward.
How soon can I have another one?
There is no fixed schedule. It is timed by how long the last one held and by clinical need — see occipital nerve block.
Will it stop an attack I am having right now?
Sometimes, but that is not what it is best at. The trials show reductions in headache frequency and intensity rather than shortening of an individual attack.2,3 For an attack that will not break, see IV migraine therapy.
Sources
- Inan LE, Inan N, Karadaş Ö, et al. Greater occipital nerve blockade for the treatment of chronic migraine: a randomized, multicenter, double-blind, and placebo-controlled study. Acta Neurol Scand. 2015;132(4):270-277. doi:10.1111/ane.12393
- Zhang H, Yang X, Lin Y, Chen L, Ye H. The efficacy of greater occipital nerve block for the treatment of migraine: a systematic review and meta-analysis. Clin Neurol Neurosurg. 2018;165:129-133. doi:10.1016/j.clineuro.2017.12.026
- Tang Y, Kang J, Zhang Y, Zhang X. Influence of greater occipital nerve block on pain severity in migraine patients: a systematic review and meta-analysis. Am J Emerg Med. 2017;35(11):1750-1754. doi:10.1016/j.ajem.2017.08.027
Being seen at Headache Express. We treat migraine, cluster and other severe headaches in St. Louis, usually the same day. Please contact us before coming in so the right treatment is ready when you arrive.