Parasym

Noninvasive Nerve Control

Andrew Kuzemczak
June 03, 2025

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TL;DR

Parasym’s Nurosym is a noninvasive, at-home vagus nerve stimulator targeting chronic conditions like ME/CFS, long COVID, and depression, leveraging electrical impulses to modulate the nervous system without surgery or prescriptions.
Clinical studies support the safety and potential effectiveness of vagus nerve stimulation for reducing inflammation, improving heart function, and enhancing brain activity, positioning Parasym strongly in the fast-growing neuromodulation market.
With a focus on serious illnesses carrying massive economic costs, Parasym aims to disrupt traditional drug and implant therapies, but its future success hinges on producing rigorous, high-quality clinical evidence.

Hi friend,

Welcome back to Future Human! I hope you enjoyed last week’s edition (#15) on Makani Science. In the previous 6 days, I have been contacted by the founder, the CEO, and the COO. We discussed the potential for future interviews and podcasts, so look out for that. Future Human may just have to start releasing round two deep(er) dives in the coming months where we revisit startups months or years after we first write about them and provide an even better informed and nuanced analysis. Stay tuned!

As for this edition, I am clearly trying to prepare myself for our fall semester Brain & Behavior unit (neuro section of our curriculum). Five weeks ago, I dove into NeuroBionics, a startup that I characterized as developing a leading minimally invasive option for brain stimulation. Recall:

“The current on-market solution for neuromodulation is deep brain stimulation (DBS). Few can deny its impact, but all must acknowledge that it requires patients to undergo surgery awake with drills burrowing into one’s skull…The startup [NeuroBionics] utilizes hair-thin, flexible bioelectronic fibers that can be delivered endovascularly—that is, through the bloodstream—eliminating the need for the surgery. Once navigated to the target area within the brain's vasculature, these fibers can deliver precise electrical stimulation through the vessel walls to modulate neural activity.”

Andrew Kuzemczak (Me), Future Human

Now, however, I want to take us to the next threshold—noninvasive. Prepare for takeoff!

So with that, let me ask you:

If you could noninvasively stimulate your vagus nerve to calm inflammation, restore balance, and treat chronic disease—would you trust it? And if you did, what else might you unlock by tapping into the body’s own neural circuitry?

The Story

Here at Future Human, we have seen many different pairs start companies together: best friends, colleagues, randos. We have yet to see siblings, however…until today.

In 2015, Nathan and Sophie Dundovic, a British brother and sister duo were mere research associates across UK universities. Despite their early career roles, they held a much more ambitious plan to bridge the gap between their complex clinical research and practical, at-home therapies. Inspired by their academic work, but frustrated by its restricted reach, they founded Parasym.

Parasym is a neurotechnology startup obsessed with noninvasive neuromodulation. Think NeuroBionics, but from outside the body. The siblings have been among the healthtech community’s most prominent champions of bioelectronic medicine (also known as electroceuticals)—a new field that treats disease not with drugs targeting cells, but with electrical impulses that modulate the nerves controlling the body’s organs and functions.¹

"I put a little electrode here in my ear. It stimulates my autonomic nervous system, trying to make my body more parasympathetic, more chill. "

- Bryan Johnson, Don’t Die

For decades, the vagus nerve has been medicine’s quiet powerhouse—regulating inflammation, heart rate, digestion, and even mood. But harnessing it has traditionally required implants, surgery, or bulky tech. Parasym is changing that. The UK-based team has developed a sleek, noninvasive device that stimulates the vagus nerve through the ear, opening the door to treating a wide range of conditions from cluster headaches to long COVID (yeah, that COVID)—all without breaking the skin.

Their current product, Nurosym, which we will dive into in The Tech, deploys targeted electrical impulses via the vagus nerve to counter dysregulation in the nervous system. The device aims to build stress resilience, accelerating recovery from stressful events and stabilizing mood swings.

Sounds too good to be true?

We’ll let the science speak in a moment.

In my reading, it is clear that Parasym fights against pharmaceuticals in the same way NeuroBionics hates (dislikes?) neurosurgery and deep brain stimulation. Why invade the body or risk side effects when you can take the path of least resistance? The Parasym team argues the primary approach of prescription pharmaceuticals for most conditions leaves many at a loss. Less than half will see benefits, and about the same percentage will struggle with side effects.²

The Tech

At Future Human, we are not here to serve as a mouthpiece for founders. Our job is to ask the hard questions and call out the shortcomings when necessary—because if we do not, what value are we actually providing?

So, is this all snake oil?

Parasym lists multiple symptoms as potential targets for their vagus nerve stimulation (VNS):

Anxiety
Chronic tiredness, fatigue, and brain fog
Diarrhea, constipation, bloating
Sleep problems
Pain, headaches
Post-viral symptoms

Before we get into the Nurosym, lets look at the science behind it.³

The vagus nerves are the main nerves of your parasympathetic nervous system (the half of your nervous system that calms you down). This system controls specific body functions such as your digestion, heart rate, and immune system. These functions are involuntary, so you lack conscious control over them.

Okay, now onto stimulation.

Vagus nerve stimulation (VNS) uses electrical impulses to stimulate your left vagus nerve. Why left? Here is your fun fact for the day. Unlike the left side, the right vagus nerve has a stronger influence on the sinoatrial (SA) node—the heart’s natural pacemaker. Stimulating the right vagus nerve can slow your heart rate too much or cause arrhythmias (irregular heartbeat).

Traditional stimulation involves implantation of a small device in your chest with wires running under your skin connecting the device and nerve. You can probably guess what happens from here. The device sends mild electrical signals through your left vagus nerve to your brain. These impulses calm down irregular electrical activity in your brain.

So what has it shown serious, science-backed use for?

The U.S. Food and Drug Administration (FDA) has approved VNS to treat epilepsy and depression that does not respond to standard therapies. It is also being investigated for:⁴

Cluster headaches
Inflammatory bowel disease (IBD)
Post-traumatic stress disorder (PTSD)
Rheumatoid arthritis

Now back to Parasym.

To be clear, Parasym is not an FDA regulated product for provider prescription, but rather a device anyone can buy for at-home use. Consider it one of the most advanced wellness products available today.

Their team is diving straight in by targeting the heart and brain—because why mess around when you can go after the toughest, most vital spots from the get-go? We ran through the randomized clinical trials they cited so you do not have to, and here are the takeaways.

Vagus nerve stimulation (VNS) is safe.⁵

They look to a 2022 study published in Scientific Reports to establish the safety profile of taVNS (transcutaneous auricular vagus nerve stimulation)
A total of 177 studies involving 6,322 subjects were included in the analysis
There were no significant differences in the risk of developing an adverse event between active taVNS and control groups

VNS shows value in atrial fibrillation (AF) treatment.⁶

Using their own device on 53 patients with paroxysmal AF (26 got treatment, 27 control), the median AF burden was 85% lower in the active group compared to the control group (p = 0.011)
Tumor necrosis factor-alpha (TNF-α) levels (inflammation marker) decreased by 23% in the active group (p = 0.0093)
Heart rate variability, a marker of the balance between the sympathetic ("fight or flight") and parasympathetic ("rest and digest") nervous systems, could be altered by active stimulation

VNS can benefit patients with diastolic (heart filling) dysfunction.⁷

Immediate effects of low-level transcutaneous vagus nerve stimulation (LLTS) on cardiac function and autonomic balance in 24 patients with diastolic dysfunction and preserved left ventricular ejection fraction (HFpEF)
Each participant underwent two separate 1-hour sessions (at least one day apart) of active LLTS and sham stimulation
LLTS led to a significant improvement in left ventricular global longitudinal strain by 1.8 ± 0.9% compared to sham stimulation (p = 0.001), indicating enhanced myocardial function, and beneficially changed HRV frequency.

VNS MIGHT improve long-COVID symptoms.⁸

20 patients experiencing long COVID symptoms ALL received 10 daily sessions of VNS
All participants self-reported significant symptom relief during the treatment period
No significant changes were observed in blood inflammatory markers (e.g., CRP, ferritin)
NOTE: no sham/control group and an open-label design are serious flaws in this study

VNS can enhance learning of letter-sound relationships.⁹

37 typically developing adults either received taVNS, sham treatment, or just followed the computer tasks without any intervention
Performance was measured using three tasks:
- Letter Identification (Letter ID): Recognizing individual letters
- Automaticity: Speed and accuracy in processing letter-sound pairs
- Decoding: Ability to read and pronounce novel words formed from the learned letters
The taVNS group showed significant improvements in both Automaticity and Decoding tasks compared to all control groups

After diving deeply into VNS research, I can confidently say there is real potential here. However, not every study is flawless. As I noted with the fourth study, some research lacks rigor—whether due to missing control groups or small sample sizes, many findings need to be re-examined. Parasym has done well with their key publications, but they should be cautious about relying on secondary studies that may be less robust. Maintaining high standards of data quality is essential. While these experimental approaches are promising, they require more thorough investigation and careful scrutiny.

The Market

The vagus nerve stimulation (VNS) market is experiencing rapid growth, fueled by rising awareness of alternative therapies and increasing prevalence of chronic and neurological disorders. Valued at $890 million in 2024, the market is expected to grow to $1.02 billion by 2025—a speedy 14.9% compound annual growth rate (CAGR). This upward trajectory continues through 2029, when the market size is projected to reach $1.76 billion, maintaining a CAGR of 14.6%. Key drivers include an aging population, rising rates of depression and epilepsy, and growing adoption of minimally invasive neurosurgical procedures.¹⁰

Advances such as robot-assisted implantation, novel electrical stimulation devices (think Parasym), and innovative stimulation techniques (think NeuroBionics) are pushing the boundaries of what VNS therapies can achieve. Companies are investing heavily in research and development, improving healthcare infrastructure, and expanding indications for treatment-resistant neurological conditions.

Parasym enters this landscape as one of many players innovating in the VNS space, but they are the most agile team up against inertia-hindered incumbents. The market features established giants like Medtronic, Boston Scientific, and LivaNova, alongside smaller specialists such as NeuroTek, Soterix Medical, and Parasym itself. Parasym’s focus on noninvasive, targeted neuromodulation makes it a standout in a field looking to just meet in the middle with a minimally invasive option. Why not skip the incision all together?

Parallel to the VNS market is the broader wearable brain device market, which grew from $380 million in 2023 to nearly $465 million in 2024, and is projected to hit $1.57 billion by 2030 with a 22.5% CAGR. These devices—ranging from EEG headbands to neurofeedback systems—address mental health, cognitive enhancement, and wellness needs. All aligns well with Parasym’s goal of leveraging our internal circuitry for therapeutic benefit.¹¹

One notable competitor in noninvasive VNS is gammaCore, the first and only FDA-cleared handheld device for treating migraines and cluster headaches. Its strong clinical backing, with over seven randomized controlled trials and numerous peer-reviewed papers, exemplifies the kind of rigorous validation that will be critical for Parasym’s long-term success.¹²

In summary, the VNS market is vibrant and rapidly evolving, with a diverse ecosystem of players and expanding applications. Parasym’s innovative technology and strategic positioning give it a promising foothold—but as the market grows, clinical validation and differentiation will be key to standing out in this competitive field.

The Sick

What if relief was just a button click away?

Imagine living with chronic fatigue so profound that getting out of bed feels like climbing a mountain. Or with brain fog that turns daily conversation into a mental workout. Now imagine that help could come not from a pill or a hospital visit—but from a handheld device used at home. This is the hope Parasym is bringing into focus with its noninvasive vagus nerve stimulation technology.

As described earlier, the vagus nerve is the body’s communication superhighway, connecting the brain to vital organs and regulating inflammation, digestion, and heart rate. When itis not working properly, the ripple effects can be debilitating—nausea, dizziness, even unpredictable shifts in blood pressure or digestion.

Parasym’s device could mean real relief for patients with conditions such as Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS), a condition that affects up to 3.3 million Americans. There is no cure and few effective treatments, leaving people with crushing fatigue, cognitive impairment, and poor sleep.¹³

Similarly, Long COVID sufferers—millions globally—often experience fatigue, brain fog, and breathlessness for months, even years. Seems we all know someone now who has experienced or is experiencing it. Emerging evidence points to inflammation of the vagus nerve and autonomic dysfunction as a root cause.¹⁴^,¹⁵

Beyond these headline conditions, the vagus nerve is implicated in a vast range of illnesses, including treatment-resistant depression, epilepsy, rheumatoid arthritis, and even obesity. It plays a central role in what researchers call the "inflammatory reflex"—a communication loop between the brain and immune system. By stimulating the vagus nerve, studies show it is possible to reduce harmful inflammation and restore balance in the body.¹⁶

Critically, most vagus nerve stimulators today require surgery or a prescription. Parasym’s device stands apart as noninvasive and accessible—lowering the barrier to entry for millions. Not a cure-all, but a step toward reclaiming daily life.

For the sick, the overlooked, and the medically underserved, the promise of a safe, at-home way to calm the body’s chaos is not just exciting—it is revolutionary.

The Economy

Parasym’s Nurosym has the potential to become a breakthrough medical device. At the same time, it may quietly deliver something just as powerful: economic relief on a massive scale.

Take Chronic Fatigue Syndrome (CFS). This debilitating condition affects up to 3.3 million Americans, robbing them of their energy, cognition, and independence—often for years at a time. There’s no cure, and recovery is rare. The financial fallout? An estimated $9.1 billion in lost productivity every year in the U.S. alone. That’s $20,000 per person, every year, for a condition that often goes undiagnosed or misunderstood.¹⁷

Then look at depression, especially treatment-resistant cases. In 2023, the U.S. economic burden of Major Depressive Disorder (MDD) reached $382 billion, driven by healthcare costs, missed work, and reduced quality of life. Imagine a world where even a fraction of those patients had access to affordable, drug-free, at-home treatment options like Parasym’s. In economic modeling, just a 50% response rate from a novel therapy could reduce national MDD costs by nearly 8% in a year—equating to billions saved.¹⁸

Now zoom out. Parasym’s Nurosym is not FDA-approved—yet—but it enters a market already hungry for solutions. Amazon alone carries hundreds of vagus nerve-related products, from wellness gadgets to clinical devices. The public is curious, and the infrastructure for direct-to-consumer healthcare is ready.¹⁹

What sets Parasym apart is its serious medical intent. While some competitors focus on wellness claims, Parasym is tackling complex, underserved conditions like ME/CFS, long COVID, depression, and dysautonomia—conditions with outsized economic impacts. And because Nurosym is noninvasive, prescription-free, and usable at home, it skips many of the access barriers that drive up healthcare costs and delay recovery.

Beyond the U.S., this matters even more. In countries with limited mental health services or stretched hospital systems, the ability to deliver care through a small, scalable device could be transformative. More people treated, fewer resources consumed, better outcomes across the board.

If Parasym can prove durable clinical benefit in these populations, it will not just be a health story. It will be an economic one—a rare example of a startup offering both patient hope and a path to national savings.

My Thoughts

Parasym is not just another wellness gadget dressed up in medical lingo—it is a serious contender in a market desperate for fresh solutions. While others slap electrodes on temples and hope for the best, Parasym is targeting the vagus nerve with precision and clinical intent. This tiny, prescription-free device is not chasing biohacker buzz; it is going after the big disorders: chronic fatigue, long COVID, depression—conditions that wreck lives and budgets.

What makes it exciting? Simplicity. Accessibility. And the audacity to believe that real healing does not have to start in a hospital. With a growing mountain of research and a market tipping toward noninvasive neuromodulation, Parasym might just be the little stimulator that could.

That said, the science has to keep up with the vision. While their cornerstone studies are strong, some of the secondary-condition research still lacks the rigor needed to match the stakes. If Parasym is serious about changing medicine, the bar should be set at the highest level—every study, every claim, every time. When you are aiming to treat the untreatable, credibility is paramount.

To more lives saved,

Andrew

I always appreciate feedback, questions, and conversation. Feel free to reach out on LinkedIn @andrewkuzemczak.