You may have come across social media posts at some point that talk about a nerve whose stimulation could solve all your physical and mental health problems. Its name seems to contradict all that potential filling reels on Instagram, infographics on Facebook, popular science books, and scientific articles. How can that nerve that seems miraculous be lazy? And how much truth is there in all that attributed to it?
Let’s start with its name. That adjective by which the tenth cranial nerve is known (there are twelve in total) does not refer to supposed idleness: vagus means wandering or vagabond in Latin and names this nerve for being “the most extensive of the cranial nerves,” explains Jaime Gonçalves Sánchez, PhD from the University of Salamanca with a thesis on its stimulation. That extension is better understood by listing some of the organs it innervates: “epiglottis, larynx, pharynx, esophagus, trachea, lungs, heart, gastrointestinal organs up to the ascending colon,” notes the expert, who adds that all this makes it participate in such diverse processes “as the regulation of cardiac function, phonation, or digestion.”
The vagus nerve is the main nerve of the parasympathetic nervous system, one of the major divisions of the autonomic nervous system, points out Judith Navarro, neurologist and coordinator of the research group Vagus nerve stimulation in autoimmune diseases at the Hospital Clínic of Barcelona. “It originates from a part of our body called the brainstem, which is in the area that connects the brain with the spinal cord. From there it travels giving smaller branches responsible for moving the vocal cords, the mobility of the esophagus, stomach, and a large part of the intestine; it reaches the lungs, gives branches that regulate heart rate, and so on.” But it not only sends information: it is also “a pathway” through which sensations from our body (having a full stomach, for example) reach the brainstem to adjust its functioning. “We can think of the vagus nerve as a two-way highway, bringing information from the organs and immune cells and carrying automatic orders from the brain to the body,” she notes.
The length of that highway, the multiple exits it has, the fact that it passes through so many organs, and that two-way direction make the vagus nerve a very studied part of our body. There is research that unravels and analyzes its role in digestion, in cardiac function, in various neurological diseases, in stress… “The most novel thing in recent years is that the participation of the vagus nerve in the modulation of systemic inflammation can be considered. That may be of interest for inflammatory autoimmune diseases such as rheumatoid arthritis or inflammatory bowel disease,” explains Javier Camiña, board member of the Spanish Society of Neurology (SEN).
The great promise of neuromodulation
The vagus nerve, also known as the pneumogastric nerve (due to its connection with lungs and stomach), touches and influences so many functions of the body that managing to control its activity “opens the doors to the treatment of many diseases that a priori have nothing to do with each other,” indicates Gonçalves, who is also an associate professor at the University of Salamanca. However, caution is needed, as for many of those pathologies there are still no “clinically approved therapies based on modulating vagus nerve activity,” he clarifies.
Among the techniques that are approved is modulation through electrical stimulation to treat “refractory or pharmacoresistant epilepsy (for those not candidates for other surgeries).” This has been used for many years. Also, in cases of pharmacoresistant depression, this type of modulation is being applied “with good results.” In both situations, it is an adjunct therapy, meaning it usually does not replace the use of drugs. What does it consist of? It involves intermittent electrical stimulation of the left vagus nerve. For this, “a simple minor surgery is necessary in which a neurostimulator or neurological pacemaker is implanted in a subcutaneous pocket in the patient’s clavicular area and a stimulation electrode on the left cervical vagus nerve.”
There are other approved and less invasive forms of modulation, through transcutaneous devices usually placed on the ear. “In Europe, there are non-invasive vagus nerve stimulation devices approved for the treatment of some headaches (migraine and cluster headache). They aim to send stimuli to the brainstem so that from there they travel to other brain areas related to pain,” explains Judith Navarro.
Returning to the idea of the two-way highway, the expert mentions that in recent years, especially after COVID-19, there is much interest in non-invasively stimulating the vagus nerve in the other direction: instead of towards the brain, from it. The idea is to modulate proinflammatory states, common in cases of post-viral fatigue that have increased after the pandemic. “There are already studies with positive results in autoimmune diseases, where the body attacks itself, such as for example lupus, although nowadays the use of non-invasive vagus nerve stimulation cannot be generally recommended,” Navarro states.
Finally, if we pay attention to posts seen on social media about this nerve, it could be activated without any device, using techniques such as breathing, massages, or splashing cold water on the face. What is true about this? “The vagus nerve is a very important component of the parasympathetic nervous system, whose function is relaxation, in opposition to the sympathetic system, which has opposite activation effects. That is why social media say that some of these activities can activate or stimulate the vagus. Probably, in most specific cases, they simply refer to achieving a state of relaxation. It has nothing to do with electrical and therapeutic stimulation directed at the nerve itself. These are different concepts and should not be confused,” warns Gonçalves.
That does not mean that the relationship between aspects such as heart rate or breathing and the vagus nerve is not being studied. “We know how many beats per minute the heart rate of a healthy person changes when the vagus nerve is activated,” points out Judith Navarro. However, it is unknown what long-term effects performing vagus nerve activation sessions through breathing might have. “An article was published in 2025 in which a team of researchers measured different data on how the vagus nerve functions before and after stimulating it with a commercial device or with deep breathing, finding similar changes in both situations. But we do not know what would happen if those people did it every day at home for weeks,” she assures.
And what about cold water on the face? What is activated, Navarro explains, is another nerve that in turn activates the vagus and causes the heart rate to drop. However, it is an immediate reflex, not something that can be done continuously for hours. “In a moment of acute stress in which your sympathetic system is very activated, it might make some sense to use this method, but not if we seek long-term effects,” she elaborates.
Regarding the possibility of massages, she warns of their danger, especially if done on the neck. “It is a maneuver we perform in hospitals together with cardiologists in some patients with syncope (fainting) in whom we believe there may be a problem of increased sensitivity of pressure receptors in the neck, but it can cause the heartbeats to become dangerously slow.” Outside of this test, which should only be done by medical professionals, she does not recommend trying it “under any circumstances.”
It is not surprising that this nerve, which touches so many functions and has so much potential, has become fashionable. Javier Camiña, from the SEN, relates this popularity to a moment in medicine when there are “various trends towards integrating therapies that affect different levels.” If it can also be done non-invasively or non-pharmacologically, the interest is greater. For Gonçalves, it has to do with the “large number” of potential applications that its modulation could have. “Among those potential applications are topics that are very trendy, such as mental health, stress, or the gut-brain axis, in which the vagus nerve can participate. However, many media or social networks fall into a simplification that can lead to using incorrect terms or those lacking sufficient scientific evidence,” he points out. The degree of truth in the promises of the nerve will be seen in the coming years.
It also affects that we live in a societal model based on a state of constant fight or flight, adds Navarro. “There are no hungry lions in the streets, but there are jobs with impossible schedules, external demands, and self-demands to be at the same time the best professional, best partner, best friend, best child, and best father or mother. Facing this prosympathetic state, the search to activate the vagus seems a logical response,” she reflects. For now, neurologists know it is a powerful tool in epilepsy and some headaches. “Hopefully, studies will continue to emerge with which we can learn to activate it to fight other diseases and it becomes one more tool, included in official guidelines and available to those who need it,” she concludes.
Neurostimulation or neuromodulation?
Both terms can be used as synonyms, but the use of neuromodulation is becoming more common compared to the more traditional neurostimulation. “When doing neuromodulation or neurostimulation, it may be of interest not to activate but to inhibit the activity of the target region or other related areas (depending on the technique and its objective or the disease to be treated). That is why it is usually preferred to say (neuro)modulation rather than stimulation, because the latter can be excitatory or inhibitory and the word stimulation is usually associated more with activation,” explains Dr. Jaime Gonçalves Sánchez, vagus nerve specialist. Still, there are many techniques that inhibit the activity of the target and are still called stimulation. “We are really regulating or modulating the function; it is not always activating or what any person understands by stimulating. The term vagus nerve stimulation was coined initially when the technique for epilepsy was described and will not be changed. But when it is used or researched for other pathologies, the way of stimulating can change a lot compared to the originally described one (in terms of the effect pursued, electrical parameters, anatomical location, and direction of stimulation, etc.),” he explains.