Across randomized trials, adverse events after occipital nerve block have not differed significantly from placebo injections. That is a genuinely reassuring finding, and it is also not the same as saying nothing can go wrong.
What the trial data show
A meta-analysis of seven randomized controlled trials in migraine found no significant difference in adverse events between occipital nerve block and control, with a risk ratio of 0.93 (95% CI 0.52 to 1.65).1 A 2024 meta-analysis in chronic migraine reached the same conclusion, with the caveat that the number of studies and the sample sizes are small enough that rare events would not be detected.2
That caveat matters. Trials of this size are good at telling you that common problems are uncommon. What the procedure itself involves is set out on the occipital nerve block page. They cannot tell you much about a complication that occurs once in several thousand procedures.
Expected effects, not complications
- Numbness over the back of the head on the treated side, wearing off with the anesthetic. This is the intended pharmacology.
- A heavy or odd-feeling scalp for a few hours, sometimes described as the ear or the top of the head feeling strange.
- Soreness at the injection site for a day or two.
- A small bruise. The area is vascular.
- Light-headedness immediately afterward, usually a response to the needle rather than the drug.
The one that drives the technique: the occipital artery
The occipital artery runs alongside the greater occipital nerve. That proximity is the single most important safety consideration, because an injection intended for the nerve can enter the artery instead. Local anesthetic delivered into an artery supplying the head is the mechanism behind the rare reports of seizure or transient neurological symptoms after this procedure.
Ultrasound shows the artery and the nerve at the same time, with Doppler to confirm which is which, and shows the needle as it advances. This is why every injection here is placed under imaging rather than by surface landmarks — see ultrasound and fluoroscopic guidance. It is a safety argument before it is an accuracy argument.
Rare but serious
Infection is the one worth naming specifically. A case report describes occipital osteomyelitis and an epidural abscess developing 16 days after an occipital nerve block in a patient with no underlying medical conditions.3 The authors’ conclusion is the right one: the procedure is safe overall, and strict aseptic technique is not optional.
Practically, that means a spreading redness, fever, or a headache and neck stiffness that is worsening rather than settling over the days after an injection is not something to wait out. Contact us, or if you are unwell, seek care the same day — see headache red flags.
If a steroid is added
Steroid brings its own small set of effects — a flush lasting a day or two, a transient rise in blood sugar that matters if you are diabetic, and with repetition, thinning or a pale patch of skin at the injection site. In one randomized trial, the only side effects reported were in patients who received triamcinolone.4 Whether a steroid is worth adding at all is a real question — see steroid or anesthetic.
Common questions
Can an occipital nerve block cause a stroke?
This is a common worry and the honest answer is that stroke is not a recognized complication of the procedure. The relevant risk is inadvertent injection into the occipital artery, which can cause transient neurological symptoms or a seizure and is the reason the injection is done under ultrasound — see why image guidance matters.
Is an occipital nerve block dangerous?
On the trial evidence, adverse events do not differ significantly from placebo.1,2 The serious complications that exist are rare and are largely addressed by imaging and aseptic technique. It is a superficial injection that takes seconds.
Will I need someone to drive me home?
No. There is no sedation and you drive yourself home — see what to expect from an occipital nerve block.
Can I drink alcohol afterward?
There is no specific interaction with the injection itself. If a steroid was used and you are diabetic, watch your glucose for a couple of days. If you are unsure, ask us at the appointment.
What should make me call you afterward?
Spreading redness or swelling, fever, or a headache with neck stiffness that is getting worse rather than better over the following days.3 Ordinary soreness that improves is expected.
Sources
- 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
- Mustafa MS, Bin Amin S, Kumar A, et al. Assessing the effectiveness of greater occipital nerve block in chronic migraine: a systematic review and meta-analysis. BMC Neurol. 2024;24(1):330. doi:10.1186/s12883-024-03834-6
- Christie SD, Kureshi N, Beauprie I, Holness RO. Occipital osteomyelitis and epidural abscess after occipital nerve block: a case report. Can J Pain. 2018;2(1):57-61. doi:10.1080/24740527.2017.1360725
- Malekian N, Bastani PB, Oveisgharan S, Nabaei G, Abdi S. Preventive effect of greater occipital nerve block on patients with episodic migraine: a randomized double-blind placebo-controlled clinical trial. Cephalalgia. 2022;42(6):481-489. doi:10.1177/03331024211058182
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.