An SPG block works because the sphenopalatine ganglion sits close to the nasal lining. That means anesthetic can reach it through the nostril. That accident of anatomy makes it one of the least invasive nerve blocks in medicine.
![Lateral fluoroscopic view during a sphenopalatine ganglion block, labeled to show the SphenoCath [soft nasal catheter] in position, the spheno-ethmoid recess and the Vidian or petrosal canal](https://headache.express/wp-content/uploads/2026/08/spg-fluoro-landmarks-v2.jpg)
What is the sphenopalatine ganglion?
It is a small collection of nerve cell bodies behind the nose, about level with the middle of the cheekbone. It is the relay for much of the autonomic supply to the face. The tearing, the blocked nostril, the flushing and the drooping eyelid of a cluster attack are that system firing.
It also carries sensory fibers relevant to migraine and to facial pain. That is why the block has uses beyond cluster.
How is an SPG block done?
You lie back or recline. A thin soft catheter (tube) is passed along the floor of the nostril. Local anesthetic is placed against the lining over the ganglion. It is held there for a few minutes. Then the other side is done.
Most people describe pressure and a bitter taste at the back of the throat rather than pain. The whole thing takes about fifteen minutes. No injection into the face, no imaging, no recovery period beyond sitting up slowly.
How well does an SPG block work?
The evidence for SPG blocks is real but more modest than for oxygen in cluster headache. Trials have generally shown a meaningful drop in pain scores over the days after treatment. They have not shown a reliable instant stop. The size of the effect varies considerably between studies and between people.
It is a reasonable option in these cases: a headache is not responding to first-line treatment, you cannot tolerate the usual drugs, or you want to avoid an injection. It is not a guaranteed switch. We say that rather than oversell it.
Who is an SPG block good for?
- People in a cluster bout who need something in addition to oxygen
- Migraine with a strong autonomic component — the attacks that feel most “sinus-like”
- People who cannot take the usual acute drugs, including some who are pregnant
- Head and neck cancer pain in the midface, nose or palate, where the mouth may be too painful or too restricted for other approaches
- Upper-jaw distributions of persistent pain after dental treatment
That fourth case is worth dwelling on. Radiation fibrosis (scarring) or surgery can limit how far the mouth opens. Then a treatment given through the nostril is not just convenient. It may be the only comfortable route.
What are the side effects of an SPG block?
Minor and short-lived: a numb throat for an hour or so, a bitter taste, and occasionally a brief nosebleed. You should not eat or drink until the throat numbness has gone away.
It is avoided if you have an active nasal infection or a recent nasal fracture.
Common questions
Does it involve a needle at all?
No. The anesthetic is delivered topically through a soft catheter in the nostril. See sphenopalatine ganglion block.
How soon would I know if it worked?
Some people notice a change during the appointment. More often the benefit shows over the next few days. It is judged over days rather than minutes, unlike oxygen in cluster. See oxygen therapy.
Can I eat afterwards?
Not until the throat numbness has gone, usually about an hour. Swallowing with a numb throat is an aspiration risk (food or drink can slip into the airway). See SPG block.
Is it safe if I get frequent nosebleeds?
Tell us. Occasional minor bleeding is a known after-effect. A bleeding tendency or a recent nasal injury changes the calculation. Contact us to discuss.
Does an SPG block hurt?
Most people describe pressure and a bitter taste at the back of the throat rather than pain. There is no needle and no injection into the face. A thin soft catheter passes along the floor of the nostril. The anesthetic is held against the lining over the ganglion for a few minutes. Then the other side is done. See do nerve blocks for headache work.
How long does an SPG block take?
About fifteen minutes from start to finish. You lie back or recline, each side is treated for a few minutes, and there is no recovery period beyond sitting up slowly. Plan to wait about an hour before you eat or drink, until the numbness in your throat has gone. See sphenopalatine ganglion block.
Can an SPG block help migraine?
Yes, for the right attacks. The ganglion carries sensory fibers relevant to migraine. The block suits migraine with a strong autonomic component, the attacks that feel most “sinus-like.” It is also a reasonable option when an attack is not responding to first-line treatment or you cannot take the usual drugs. Expect the benefit to show over days. See when a migraine will not break.
Who should not have an SPG block?
The block is avoided if you have an active nasal infection or a recent nasal fracture. A bleeding tendency or a recent nasal injury also changes the calculation. That is because occasional minor nosebleeds are a known after-effect. Tell us about any of these before the appointment so we can plan the right treatment for you. See contact us.
The SPG block goes in through the nose, with no needle and no sedation, and most people drive themselves home. It is among the fastest options at our St. Louis headache clinic; details are on the SPG block page.
Sources
- Cady R, Saper J, Dexter K, et al. A double-blind, placebo-controlled study of repetitive transnasal sphenopalatine ganglion blockade with tx360(®) as acute treatment for chronic migraine. Headache, 2014. PMID 25338927. pubmed.ncbi.nlm.nih.gov
- Barad M, Ailani J, Hakim SM, et al. Percutaneous Interventional Strategies for Migraine Prevention: A Systematic Review and Practice Guideline. Pain medicine (Malden, Mass.), 2022. PMID 34382092. pubmed.ncbi.nlm.nih.gov