Is Vagus Nerve Dysfunction Real? Separating Fact from Fiction

As one does when procrastinating, I have been scrolling on TikTok and noticed several posts about vagus nerve dysfunction. I have a master's in Biomedical Sciences, and my bachelor's thesis was focused on neuroscience and neuroanatomy, so I immediately went down that rabbit hole.

The vagus nerve is essential for the parasympathetic nervous system and is one of the main drivers of the ‘rest and digest’ response. It quite literally impacts digestion, stress resilience, heart rate, and breathing. So, with people posting signs of dysfunction and morning routines focused on resetting the vagus nerve, I became interested in what this diagnosis is and how exactly it affects the people posting about it on social media.

Vagus nerve dysfunction is not an officially recognized medical diagnosis but has become a keyword and an umbrella term for issues related to the vagus nerve function. We felt it was important to break down this topic to help you understand what the vagus nerve does and differentiate between influencer or alternative health enthusiast advice and established medical knowledge.

How the vagus nerve works

The vagus nerve starts in the medulla oblongata, located in the brain stem, and travels down the neck and spine, branching off to innervate targeted internal organs. This is why this cranial nerve is sometimes called the ‘wandering nerve.’

The branches innervating the vital organs are made up of efferent and afferent fibers. Efferent fibers carry information from the brain to the organs, influencing their function accordingly. Afferent fibers carry sensory feedback about the organ's function back to the brain, where the information is processed, and adjustments in parasympathetic and sympathetic signaling are made. I have written an in-depth article on vagus nerve function and reflexes if you want more details.

When is vagus nerve dysfunction a medical concern?

While vagus nerve dysfunction is not a medical diagnosis, there are several cases in which the vagus nerve activity may be affected.

1. Vagal nerve injury due to surgery or trauma. Vagal nerve injury is a feared and unlikely complication of antireflux or cardiac surgery, due to its close proximity to the esophagus and heart. It may also occur on rare occasions with a severe upper neck injury, but the survival rate is low.
2. Autonomic nervous system disorder. Conditions such as diabetic neuropathy that affect the autonomic nervous system may impair vagus nerve function.
3. Vasovagal syncope. A temporary overactivation of the vagus nerve can cause vasovagal syncope, which leads to fainting. This may be caused by long periods of standing, overheating, heavy strains, seeing or having blood drawn, etc. While most people recover quickly, frequent fainting and low blood pressure may be signs of an underlying issue.

Numerous symptoms are attributed to vagal nerve dysfunction, but other underlying issues may cause them. The table below shows the proposed symptom, its connection to the vagus nerve function, and other possible causes.

It is important to remember that you must look for patterns and prolonged symptoms where they do not make sense. For example, if your heart is racing, your digestion is impaired, and you feel like you may vomit after sprinting for a bus, this is an unpleasant but normal bodily response. This was a fight-or-flight situation. However, if you repeatedly feel like you may have a panic attack but are at home trying to make some food, this may be a sign of an underlying issue.

Do these symptoms really point to the vagus nerve?

Issues with the vagus nerve have become quite the scapegoat on social media. Digestive issues? Heart rate changes? Neck pain or feeling ‘off’? Yeah, vagus nerve dysfunction.

Unfortunately, it is way more complicated than that, and all symptoms have numerous alternative causes. As I previously mentioned, vagus nerve dysfunction is not a medical diagnosis. The nerve can get damaged during surgery or due to nervous system disorders, but in those cases, the consequences are much more severe than an upset stomach and a headache.

If you look closely at the symptoms attributed to impaired vagus nerve function, you will see an overlapping theme. Most of them can be caused by stress, lack of sleep, diet, hydration, and lifestyle. The good news is that these factors are much easier to address than nerve damage. However, if you are healthy, manage your lifestyle, and are experiencing persistent unexplained symptoms, like severe bloating, anxiety, and high heart rate, you should consult your doctor to check if something is out of order and needs treatment.

The vagus nerve plays a key role in involuntary bodily functions. But just because it is involved in how something works does not mean that vagus nerve dysfunction is why you have symptoms.

Can doctors test for vagus nerve problems?

There are no official medical tests for vagus nerve dysfunction, but there are some ways to assess the parasympathetic system and symptoms involving vagus nerve activity.

These indirect tests include:

• Heart rate variability (HRV). It reflects variation in the time interval between heartbeats, which is influenced by exercise, respiration rate, and metabolic rate. It is directly controlled by the autonomic nervous system. Generally, higher HRV is associated with greater parasympathetic activity, and faster and better recovery after environmental stressors.
• Post-exercise HR recovery. Vagus nerve signaling post-stressors, such as exercise, reduce heart and breathing rate and restore homeostasis. Quicker recovery implies better vagal signaling, but it may also be influenced by fitness levels.
• Pharyngeal gag reflex test. The patient has to open their mouth and say ‘aah’ to see if the palate lifts evenly and the uvula remains centered. The back of the throat on each side is gently touched with a tongue depressor to evoke a gag reflex. If one side does not react, it could indicate glossopharyngeal or vagus nerve damage. However, the absence of the gag reflex can also be normal in some healthy individuals.

Various tests can be used to determine the state and function of the autonomic nervous system to some extent. However, you must remember that feedback relies on receptors, and the brain processes the input and ‘orders’ vagus nerve signaling. Thus, issues could occur in the vagus nerve pathway but not directly due to vagus nerve dysfunction.

Can you really ‘heal’ your vagus nerve?

Several practices, such as breathing exercises, meditation, yoga, and exercise, are being promoted as beneficial for ‘reversing’ vagus nerve dysfunction. While all of these have merit, they are not proven to improve vagus nerve function directly, and you probably do not need to ‘heal’ your vagus nerve because it is not broken. These practices contribute to mental and physical health and help reduce stress for many, promoting relaxation.

If you are experiencing chronic stress, you must look at your lifestyle and sleep patterns and find ways to incorporate more self-care practices. If you feel anxious, stressed, and otherwise unwell despite having a balanced lifestyle, you may have underlying issues and should consult your doctor or may want to consider therapy.

Health and wellness habits aside, vagus nerve stimulators (VNS) are also available. The FDA has approved invasive VNS for drug-resistant epilepsy and treatment-resistant depression only. Transcutaneous VNS is not invasive and available for at-home use, but there are no regulations or standardized guidelines regarding frequency, session timing, or placement.

Bottom line: choose science over simplified labels

The vagus nerve plays a vital role in maintaining homeostasis in the body. It sends feedback from the vital organs to the brain and sends parasympathetic nervous system signals back to the organs accordingly. The vagus nerve connects to internal organs, from the heart rate to the digestive system.

Despite trending on social media, vagus nerve dysfunction is not an official medical diagnosis and often oversimplifies nuanced and complex symptoms and potential underlying medical issues. If you live a healthy and balanced lifestyle but persistently experience symptoms like anxiety, digestive issues, fatigue, or any other unexplained issues, you should consult your healthcare provider to check for nutrient deficiencies or other issues before self-diagnosing with vagus nerve dysfunction.

The bottom line is that we live in an age where knowledge about health and wellness is widely available, which may be helpful in some cases. Still, you should prioritize legitimate medical advice tailored to you and your health history. A healthy and balanced lifestyle should not be complicated, but serious, unexplainable symptoms should not be written off.