Vagus Nerve Stimulation Devices: What Are They And Should You Use Them?

In recent years, there has been a growing interest in neuromodulation techniques or methods to alter nerve activity in order to achieve health benefits. One such technique is vagus nerve stimulation (VNS), which has decades of use and scientific backing for specific therapeutic uses.

While invasive VNS is an FDA-approved method for treatment-resistant depression and epilepsy, non-invasive VNS devices are currently under investigation for an expanding scope of applications. These, among others, include stress and anxiety relief, improved sleep, and reduction of cluster headaches and migraine.

Not all devices reaching the market have the same level of evidence for their safety and efficacy. Thus, familiarizing yourself with the available scientific evidence and potential risks before investing in a vagus nerve stimulation device seems crucial.

What is the vagus nerve?

The vagus nerve is the longest cranial nerve. It branches out to facilitate communication between the brain and a range of internal organs, including the heart, lungs, and gastrointestinal tract, among others. Around 80% of vagus nerve fibers send information about the state of internal organs to the brain, and roughly 20% carry signals from the brain to the body.

Although we call it a nerve, there are, in fact, two vagus nerves in our bodies: the left and right vagus nerves. Both of them are the main components of the 'rest and digest' system, also known as the parasympathetic nervous system (PNS). It counteracts the 'fight or flight' response or the sympathetic nervous system, which typically predominates when an individual is in danger or feels stressed out.

By influencing your heart rate, breathing, and digestion, the PNS, including the vagus nerve, is essential for maintaining the physical and mental balance in our bodies. It allows the body to relax after the danger or stress has passed.

Deep dive into vagus nerve stimulation

Besides VNS use for treatment or management of medical conditions, it has also sparked interest among healthy individuals. This comes as no surprise, considering the role of the vagus nerve in regulating a range of physiological functions. External stimulation methods are being investigated for various therapeutic applications, ranging from weight loss to stress management and mood regulation.

Overall, vagus nerve stimulation methods include:

• Natural methods for stimulating the vagus nerve indirectly
• Invasive VNS
• Non-invasive VNS devices

	Invasive	Non-invasive	Natural
Stimulation type	Surgical procedure: implantable VNS device.	External VNS by the use of electrodes placed against the skin.	Indirect VNS stimulation methods: singing, gargling, cold stimulation.
Approval or clearance by the regulatory body	FDA approved for drug-resistant depression, refractory epilepsy, and post-stroke rehabilitation.	Some* are FDA-cleared (e.g., gammaCore™), or CE-certified medical devices in Europe (e.g., NEMOS®).	N/A
Scientific evidence and potential benefits	Reduced seizure frequency, improved depression, and similar.	Ranging from anxiety and stress relief to management of pain and inflammation.	Mostly anecdotal; studies are limited in quantity and quality.
Potential concerns and considerations	Surgery-related complications; invasive nature; narrow applicability.	The safety and efficacy of most commercially available tVNS devices are not established.	Individual results vary; difficult to assess the effectiveness.

*gammaCore™ is FDA-cleared for managing episodic cluster headaches and migraines. NEMOS® has European certification for the treatment of depression, epilepsy, and pain.

Natural ways

Social media platforms are brimming with advice on possible vagus nerve activation methods, ranging from icing your vagus nerve to massaging it. However, the research on natural stimulation methods is rather scarce.

For example, specific breathing techniques have been found to enhance vagal tone, as measured by heart rate variability (i.e., variation in time between consecutive heartbeats). A 5-minute-long practice of slow and deep breathing was also helpful in relieving self-reported anxiety, especially in older adults. According to the study authors, breathing practice presents itself as a cost-effective and practical way to enhance parasympathetic system activity.

Additionally, some people report having experienced temporary stress relief from vagus nerve massage. However, there is hardly any scientific evidence to suggest that the benefits exceed those of a traditional massage. Moreover, the exact massage techniques and pressure points are poorly documented, and the effectiveness of at-home vagus nerve stimulation methods is not established.

Invasive VNS devices

Invasive or implantable vagus nerve stimulation is a surgical procedure that has been approved by the U.S. Food and Drug Administration (FDA) for the treatment of drug-resistant epilepsy and depression. Recently, it has also been approved for being used along with rehabilitation exercises to treat impaired motor function after stroke.

This invasive procedure requires a pulse generator to be implanted under the skin in your chest, with a wire that is wrapped around the left vagus nerve in the neck. The pacemaker-like device sends electrical impulses to the brain via the vagus nerve in order to influence brain activity. The goal is to reduce seizures or improve depressive symptoms.

For many patients, invasive VNS is a life-long treatment that requires regular medical appointments following the implantation of a vagus nerve stimulator. This is crucial for patient monitoring, as well as the adjustment of the stimulation parameters — a key part of optimizing treatment effectiveness.

Non-invasive VNS devices

The non-invasive VNS devices are designed to send mild electrical pulses through the external electrodes placed against your skin, hence the name transcutaneous VNS (tVNS).

The non-invasive VNS (nVNS) can be divided into the following categories based on the site of stimulation:

• Transcutaneous cervical vagus nerve stimulation (tcVNS) devices aim to stimulate the cervical branch of the vagus nerve at the neck region.
• Transcutaneous auricular vagus nerve stimulation (taVNS) devices aim to stimulate the auricular branch of the vagus nerve. The device is placed against the tragus or concha of the outer ear.

The interest in these devices has soared in recent years due to their non-invasive nature, potential for use in both patients and healthy individuals, as well as convenience. They include both prescription devices (e.g., gammaCore®; NEMOS® in Europe) and commercial tVNS devices that can be bought online and don’t require a doctor’s authorization. However, the latter devices often lack regulatory approval and clinical validation.

tVNS devices differ in terms of application site, stimulation parameters, and the potential benefits they may deliver. No studies have directly compared the effectiveness of different tVNS devices. It is not yet clear how most tVNS devices that reach the market compare to those used in scientific research or clinical settings.

Regulation of VNS devices

Users who are trying to choose the best vagus nerve stimulation device should explore the market cautiously. While the FDA regulates medical devices, most brands that manufacture VNS devices for at-home use have not sought approval from regulatory authorities.

Those that have typically chose the 510(k) clearance pathway. This is the FDA regulation that is commonly sought for Class II medical devices before they reach the market. It requires performance testing to determine if the device is safe and substantially equivalent to its predicate device(s).

This is different from the FDA-approval, which is granted for Class III medical devices that sustain or support life, pose significant health risks, or are implantable (such as invasive VNS systems).

While invasive VNS devices are FDA-approved for the treatment of medical conditions, most commercial VNS devices have not been cleared by the FDA or any other regulatory body. This poses questions about the safety and effectiveness of such devices.

Are vagus nerve stimulation devices effective?

Invasive VNS is a neuromodulation technique that is backed by scientific evidence and is being used effectively in clinical settings to treat medical conditions. In contrast, non-invasive VNS devices have emerged more recently. The scarcity of research limits our understanding of who would be the most suitable candidate for tVNS and how effective it is for different health concerns.

The effectiveness of tVNS is likely to vary based on several factors. These include:

• Specific parameters of the device
• Individual health characteristics
• Health concerns being targeted with tVNS
• Clinical evidence to back up the proposed benefits

Despite the emerging clinical evidence showing the effects of tVNS, there is no consensus on the optimal stimulation parameters (e.g., intensity, waveform, frequency), session duration, or frequency. The effectiveness of tVNS devices requires further research to substantiate the proposed benefits.

Individuals who are interested in trying out tVNS should seek professional advice to help determine if this neuromodulation technique is right for them.

Vagus nerve stimulation device benefits

While the vagus nerve does contribute to important physiological functions in our bodies, the research on non-invasive VNS is still in its infancy. Yet, based on the theoretical understanding of the vagus nerve anatomy and its functions in our body, as well as the emerging clinical evidence, several benefits have been proposed.

Depression treatment

In both Europe and the United States, invasive VNS is approved as an adjunct treatment for drug-resistant depression. Following this, researchers have been trying to determine whether transcutaneous VNS can be considered a safer, more accessible alternative for depression treatment.

A small pilot study examined the effects of daily tVNS in individuals diagnosed with major depression. Reduction in depressive symptoms was observed following auricular vagus nerve stimulation for two weeks.

A meta-analysis of 12 randomized controlled trials suggests that taVNS may be considered an effective and safe method for depression treatment. However, the authors note that in most of the included studies, the participants had mild to moderate depression. This limits our understanding of whether taVNS may be effective for more severe cases of depression.

Moreover, in a systematic review with more robust study selection criteria, a different conclusion was reached. According to the authors, more high-quality research is needed before tVNS can be recommended for the treatment of depressive symptoms or anxiety.

Stress management

As shown by studies utilizing brain imaging, blood biomarkers, and wearable sensing devices, tVNS holds promise for managing stress-related health conditions. The pathways in which tVNS may influence stress physiology include:

• Enhanced autonomic nervous system function
• Reduced inflammation
• Modulation of brain circuits implicated in emotion and stress regulation

The influence of these pathways is particularly relevant to psychiatric disorders, including post-traumatic stress disorder and depression. In fact, the physiological response to stress was found to be modulated by the tcVNS in individuals with post-traumatic stress disorder (PTSD). The beneficial effects included lowered heart rate and increased dilation of peripheral blood vessels, among others. This points to enhanced recovery after traumatic stress.

A recent pilot study has shown the potential of tcVNS to influence autonomic and hormonal responses to stress. The levels of ghrelin (known as a hunger hormone that gets elevated in times of stress) were reduced after exposure to stressful stimuli in the tcVNS group as compared to the sham group that received no treatment.

Although limited in quality and quantity, these findings highlight the potential role of taVNS in attenuating physiological responses to stress.

Cluster headache and migraine relief

Both animal and human studies suggest that VNS may produce analgesic effects. It has been proposed that VNS inhibits the transmission of pain signals and has anti-inflammatory effects.

In 2017, the first non-invasive VNS device was cleared by the FDA for the treatment and prevention of episodic cluster headaches and migraine. gammaCore® is currently available only by prescription, as your healthcare provider should determine whether this device is right for you.

In a systematic review published in 2022, both cervical and auricular tVNS have been shown to have a positive effect on migraine control and pain reduction. A more recent review suggests that some of the beneficial effects partially depend on the stimulation site. The effects somewhat differ depending on whether you stimulate the auricular or cervical branch of the vagus nerve.

While the underlying mechanism of how VNS may improve migraine is not fully understood, it has been suggested that VNS may inhibit cortical spreading depression. This is a slow-moving wave of electrical activity in the brain that has been linked to migraine auras. Other theoretical explanations include the influence on neurotransmitter systems, suggested to play a role in the emergence of migraine, as well as the anti-inflammatory effects of VNS.

Sleep

According to one cohort study, individuals over the age of 55 reported improved quality of life, sleep, and mood after two weeks of daily tVNS. Furthermore, the participants showed improvement in certain indicators of vagal tone and, as the study authors postulate, the shift toward parasympathetic nervous system activity. Although the study has some limitations, such as a lack of a control group, it sheds some light on the link between tVNS and sleep.

In another study, tVNS was administered for four weeks to people living in high altitudes and suffering from insomnia. In addition to reduced anxiety levels, tVNS was associated with improved sleep quality. The benefits, as measured by polysomnography (a diagnostic test administered while you are asleep), included taking a shorter time to fall asleep, as well as a longer duration of deep sleep.

While the studies are limited in quantity, they provide some preliminary evidence for the role of tVNS in improving sleep quality.

Cognitive benefits: enhanced memory and attention

The link between vagus nerve stimulation and memory enhancement has been observed in trials with depression and epilepsy patients. Animal studies show that VNS may impact neural pathways of memory by influencing neurotransmitters in the brain.

According to a recent systematic review, there is some limited evidence to suggest that VNS may improve memory and attention in epilepsy patients. Yet the evidence for patients with mood disorders is mixed.

While the above evidence comes from invasive VNS, non-invasive devices have also been used to study memory enhancement in healthy people. For example, in a study with 48 healthy young adults, taVNS was found to improve certain aspects of working memory. This type of memory is related to short-term memory and is required for carrying out cognitive tasks.

Finally, a review of 19 studies looked at the effect of the auricular tVNS on cognitive functioning in healthy individuals. It was concluded that taVNS may positively impact cognition, especially executive functions. Yet more research is needed to determine the optimal stimulation parameters.

Are there any risks of vagus nerve stimulation devices?

While VNS therapy itself is generally considered safe, it is nevertheless associated with several risks. The adverse effects are typically linked to the vagus nerve stimulation itself, surgery-related complications (e.g., infection and inflammation at the site of surgery), or device malfunction.

The most commonly reported side effects include cough, shortness of breath, tingling, prickling or numbness in the skin, voice alteration, headache, and pain.

When it comes to non-invasive VNS, the following side effects have been observed in clinical trials:

• Tingling, redness, or skin irritation at the site of stimulation
• Headache
• Dizziness
• Nausea
• Nasopharyngitis (inflammation of the nasal passages or throat)
• Facial drooping

Contraindications and safety precautions:

• VNS devices should not be used by pregnant or breastfeeding individuals or those under the age of 18.
• If you have a medical condition, are currently taking medication, or have any implantable device (e.g., hearing aid implant, pacemaker, and similar), you should seek medical advice before using tVNS.

Also, note that it is hard to evaluate the risks of most commercial tVNS devices that one can buy online. Most of them have not been tested for safety or efficacy. Moreover, it is not clear how these devices compare to clinical tVNS devices.

In clinical trials, vagus nerve stimulation is performed in a controlled environment by highly skilled research professionals who are familiar with the anatomy and physiology of the vagus nerve. The clinical VNS device is likely to have undergone a careful developmental process and scrutiny before being used. This, unfortunately, is not always the case with all commercial tVNS devices.

How to correctly use vagus nerve stimulation devices?

tVNS devices differ considerably in terms of their parameters, functionality, and application site. Ideally, you should be using a tVNS device under the supervision of a healthcare provider who is familiar with the VNS technique. In order to use the device correctly, consider the following recommendations:

1. Adhere to the recommended usage guidelines that are specific to each device.
2. Familiarize yourself with stimulation points that should be clearly indicated in the user manual of each device. The most commonly used stimulation sites include the tragus or concha of the ear and the side of the neck. Pay attention to the instructions on which ear (or side of the neck) you should be aiming to stimulate.
3. If required, make sure to apply the conductive gel (usually provided with the device) to the stimulation surface. This helps the electrical signal to effectively reach its target.
4. Do not exceed the recommended session duration. This may vary from less than two minutes to half an hour or, in some cases, even an hour.
5. Familiarize yourself with contraindications and seek medical advice if in doubt about whether tVNS is right for you.

Further reading on vagus nerve stimulation devices

If you are interested in reading more about vagus nerve stimulation, consider the following review papers.

• For a deeper understanding of the differences between invasive versus non-invasive vagus nerve stimulation devices, turn to the review paper published in the European Journal of Neurology. Learn more about the advantages and drawbacks of each stimulation method.
• According to a recent in-depth review, medical applications of taVNS include epilepsy, depression, tinnitus, and post-stroke rehabilitation. Familiarize yourself with clinical trials that utilized taVNS for the management of these conditions.
• Both animal and human studies suggest that VNS may have pain-relieving effects. Find out more about the proposed mechanisms of action, including inhibition of pain signals and anti-inflammatory effects.
• taVNS is considered a safe method for clinical interventions, yet not without potential side effects. For further reading on the safety of taVNS, turn to the systematic review and meta-analysis assessing the incidence rate of adverse effects of taVNS.
• Learn more about the anti-inflammatory properties of vagus nerve stimulation. While animal studies show promising results, there is currently insufficient evidence from human clinical trials.

How to choose the best vagus nerve stimulation device

If you are interested in exploring the options of at-home vagus nerve stimulation devices, there are certain factors to consider. Bear in mind that the devices differ in terms of their technical features, scientific backing, user-friendliness, and customer reviews. Consider what matters most to you, and choose accordingly.

Clinical validation. Having a device tested in a clinical trial provides some reassurance that the device is effective and safe for use. Clinical studies can also inform us about any adverse effects that one may experience when using the device.

Regulatory approval. Devices that are approved by the European Medicines Agency (EMA) or cleared by the U.S. Food and Drug Administration (FDA) should be prioritized. This gives the reassurance that the device meets the quality and safety standards set by the regulatory bodies.

Personalization. The option to choose stimulation parameters, such as stimulation intensity or mode, is important for making VNS tailored to your individual needs.

Customer service. Choosing a brand with well-regarded customer service comes in handy if any questions arise regarding the tVNS device use.

📝Healthnews editor's top picks

While the market is brimming with non-invasive vagus nerve stimulation devices that can be used at home, finding the right one for you may be challenging. Hence, we have curated a list of three tVNS devices that, in our opinion, are worth trying.