The usual side effects of an occipital nerve block are numbness over the back of the head, soreness or a small bruise at the injection site, and brief light-headedness. The serious risks are injection into the occipital artery and infection. These are rare. Ultrasound guidance and strict aseptic (germ-free) technique address them.
Across randomized trials, adverse events after occipital nerve block have not differed significantly from placebo injections. That is a truly reassuring finding. But it is not the same as saying nothing can go wrong.
How safe is an occipital nerve block?
One meta-analysis pooled seven randomized controlled trials in migraine. It 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. It added a caveat: the number of studies and the sample sizes are small. They 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. They cannot tell you much about a complication that happens once in several thousand procedures.
What are the common side effects of an occipital nerve block?
- 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 closeness is the single most important safety issue. That is because an injection meant for the nerve can enter the artery instead. Local anesthetic delivered into an artery that supplies the head is the mechanism behind the rare reports of seizure or transient (short-lived) neurological symptoms after this procedure.
Ultrasound shows the artery and the nerve at the same time. Doppler (a blood-flow view) confirms which is which. It also shows the needle as it moves forward. This is why every injection here is placed under imaging, not by surface landmarks — see ultrasound and fluoroscopic guidance. It is a safety argument before it is an accuracy argument.
Can an occipital nerve block cause an infection?
Infection is the one worth naming specifically. A case report describes two problems 16 days after an occipital nerve block: occipital osteomyelitis (bone infection) and an epidural abscess. The patient had no underlying medical conditions.3 The authors’ conclusion is the right one: the procedure is safe overall, and strict aseptic technique is not optional.
In practice, some signs are not something to wait out in the days after an injection. That means spreading redness, fever, or a headache and neck stiffness that is getting worse rather than settling. Contact us, or if you are unwell, seek care the same day — see headache red flags.
What side effects does a steroid add?
Steroid brings its own small set of effects. These are a flush lasting a day or two, a brief 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. The honest answer is that stroke is not a recognized complication of the procedure. The relevant risk is accidental injection into the occipital artery. That can cause transient neurological symptoms or a seizure. It 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. They are largely addressed by imaging and aseptic technique. It is a shallow injection that takes seconds.
A short-lived flare of the headache in the first days after a block is covered in Can an occipital nerve block make a headache worse?
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, not better, over the following days.3 Ordinary soreness that improves is expected.
The warning signs that need same-day care are listed in headache red flags.
How long do occipital nerve block side effects last?
Most are short. The numbness over the back of the head wears off as the anesthetic does. A heavy or odd feeling in the scalp usually lasts a few hours. Soreness at the injection site lasts a day or two. If a steroid was added, a flush can last a day or two. Blood sugar can also run higher for a couple of days if you are diabetic.
Does an occipital nerve block have long-term side effects?
The usual effects wear off within hours to a couple of days. The lasting one to know about comes from steroid. With repeated injections at the same spot, the skin can thin or form a pale patch. That is part of why adding a steroid at all is a real question. Infection is the rare serious risk. That is why strict aseptic technique is not optional.
Why do I feel light-headed after an occipital nerve block?
Brief light-headedness right after the injection is common. It is usually a response to the needle, not the drug. It passes quickly. It is not the same as the rare reaction caused by anesthetic entering the occipital artery. Ultrasound guidance prevents that risk by showing the artery, the nerve and the needle at the same time.
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
Side effects from an occipital nerve block are usually brief, and you leave knowing what to watch for. It is done in the office at our headache clinic in St. Louis, under image guidance when the target calls for it.