Vagus Nerve: What to Know

Medically Reviewed by Mahammad Juber, MD on October 06, 2022
5 min read

The vagus nerve is an integral part of your autonomic nervous system. This part of your nervous system controls the things your body does without your conscious input, such as breathing, digesting food, and sweating. 

Specifically, the vagus nerve is part of the parasympathetic nervous system, which calms your body after you've been in a stressful situation. The vagus nerve carries signals from your brain to other parts of your body, like your heart or intestines, to initiate this process.

The vagus (vagal) nerve is also known as the 10th cranial nerve or cranial nerve X. It starts in your medulla oblongata, a part of the brain that connects to the spinal cord, and splits off into many branches that extend down through your neck to your vital abdominal organs.

This long nerve makes up 3/4 of the nerve tissue in your parasympathetic nervous system. In fact, the vagus nerve is the longest of any of the 12 cranial nerves.

The vagus nerve helps your body exit its fight-or-flight mode. You can remember what the parasympathetic nervous system helps you to do with little rhymes that describe its functions, like "feed and breed" and "rest and digest." 

The vagus nerve provides signals from your brain to your body, regulating your:

  • Heart rate
  • Taste
  • Speech
  • Skin sensations
  • Muscle sensations
  • Immune response
  • Respiratory rate
  • Blood pressure
  • Mucus production
  • Saliva production
  • Digestion
  • Frequency of urination
  • Mood

The opposite of the parasympathetic nervous system is the sympathetic nervous system. This is another part of the autonomic nervous system. It helps you enter fight-or-flight mode when needed. 

Manipulation of the vagus nerve may also be instrumental in treating certain illnesses:

Treatment-resistant depression. While researchers are still investigating how the vagus nerve is involved in mental health, studies show that vagus nerve stimulation treatments can help depression that is resistant to treatments like talk therapy or prescription drugs. Experts believe this may be due to a connection between mental health and a healthy gut biome. In one study of people with treatment-resistant depression, after 1 year of vagus nerve stimulation treatment, 53% of participants responded to the treatment and 33% went into remission.

Inflammatory bowel disease. IBD is actually a term for two diseases: Crohn's disease and ulcerative colitis. Unfortunately, the medications for these diseases can have some strong and undesirable side effects. Because the vagus nerve typically sends anti-inflammatory signals, experts are exploring vagus nerve stimulation as an alternative option for treatment for those who want to avoid side effects from traditional medications.

Epilepsy. The FDA has approved vagal nerve stimulation therapy for people with epilepsy. This device is implanted into people with epilepsy and sends electronic impulses to calm the vagal nerve and prevent irregular brain activity. While it is not a cure for epilepsy, it may reduce the duration, frequency, or severity of seizures. Doctors are still researching exactly how the vagus nerve relates to epilepsy.

The vagus nerve splits in two as soon as it leaves the medulla oblongata. The left vagal nerve runs down the left side of your neck, and the right vagal nerve runs down your right side. This nerve extends all the way from your brain to the large intestines: down your neck, through your chest, around your heart, around your lungs, and through your abdomen and intestines. Below your esophagus, the two sides join once more to form the "vagal trunk," which goes down into your abdomen before branching off once more.

This nerve's branches provide nerve signals to specific areas of the body:

  • The inferior ganglion branch sends signals to your voice box and throat. 
  • The superior ganglion branch connects to your spine and ears.
  • The vagus nerve branch delivers nerve signals to your esophagus, heart, and lungs.

Because the vagus nerve affects so many bodily functions, there are many signs that you may have a condition that causes vagal nerve dysfunction, including:

  • Acid reflux
  • Abdominal pain
  • Bloating
  • Lack of a gag reflex
  • Difficulty swallowing
  • Dizziness
  • Fainting
  • Hoarse voice
  • Wheezing
  • Unexplained weight loss
  • Loss of appetite
  • Feeling full after eating very little food
  • Nausea
  • Vomiting
  • Chronic mood issues or disorders

Your vagus nerve helps with many functions of the body, so its malfunctioning can cause a wide variety of conditions. Scientists are still studying how it may affect mental health, chronic headaches, and even Alzheimer's.

Other related conditions include:

Gastroparesis. As a result of this condition, food stops moving through your digestive system. Some cases of gastroparesis are caused by a damaged vagus nerve resulting from surgery, diabetes, an infection, or an auto-immune disorder.

Vasovagal syncope. If you have this condition, you are more likely to faint in hot weather, when you are hungry or anxious, or in other uncomfortable conditions. The vagus nerve will overreact to these situations and causes your blood pressure to drop very quickly, making you dizzy or causing a fainting spell.

Keeping your vagus nerve healthy involves doing many of the things you might do to keep yourself healthy in general. Eat a well-balanced diet with plenty of fresh fruits and vegetables. Make sure to exercise for at least 30 minutes several times a week. Manage chronic health conditions like high blood pressure or diabetes. Additionally, practicing mindfulness, meditation, or yoga can help to keep your vagus nerve healthy by calming your nervous system.

Experts believe there is a strong connection between the gut biome and a healthy vagus nerve because the bacteria in our guts can produce neurotransmitters such as dopamine, so they suggest taking prebiotics and probiotics to keep your gut biome healthy.

Singing may also stimulate your vagus nerve, keeping it healthy as vibrations stimulate the parts of the vagus nerve in the back of your throat. If you don't like to sing, gargling has the same effect.