Neuritis is inflammation of a nerve or group of nerves, causing pain, weakness, numbness, or loss of function in the affected area. It can strike almost any nerve in the body, from the optic nerve behind your eye to the network of nerves running down your arms and legs. Some forms hit suddenly and resolve within weeks, while others develop gradually and require long-term management.
The term is broad. Depending on which nerve is inflamed and what triggered it, neuritis can look very different from person to person. Understanding the specific type matters because it shapes both the symptoms you experience and how recovery plays out.
What Happens Inside an Inflamed Nerve
Nerves are insulated by a fatty coating called the myelin sheath, which helps electrical signals travel quickly and smoothly. In neuritis, immune cells infiltrate the nerve and attack either this protective coating, the inner nerve fiber (the axon), or both. When the myelin sheath breaks down, signals slow or short-circuit. When the axon itself is damaged, the nerve may stop transmitting signals altogether.
This immune attack involves several types of inflammatory molecules. White blood cells migrate into the nerve tissue, and the cells that normally maintain the myelin sheath begin to malfunction. The result is a nerve that can no longer do its job properly, whether that job is carrying sensation from your fingertips, controlling a muscle in your shoulder, or transmitting visual information from your eye to your brain.
Common Types of Neuritis
Optic Neuritis
Optic neuritis inflames the nerve that connects your eye to your brain. It typically affects one eye at a time and comes on over hours to days. The hallmark symptom is pain with eye movement, present in about 92% of cases. Vision becomes dim, blurry, and washed out. Colors look dirty or pale through the affected eye, and you may notice a dark spot in the center of your visual field.
One distinctive feature is the Uhthoff phenomenon: your vision temporarily worsens when your body temperature rises, such as after exercise or a hot shower. Two-thirds of patients have visual acuity below 0.5 (roughly 20/40 or worse) during an episode. Most people recover significant vision over weeks to months, but optic neuritis carries an important long-term implication. It accounts for about 43% of the isolated neurological episodes considered potential precursors to multiple sclerosis, and half of all people with typical optic neuritis go on to develop MS within 15 years. A brain MRI at the time of diagnosis helps assess that risk. If no suspicious lesions appear on the scan, only about 25% develop MS. If three or more lesions are visible, that number rises to 78%.
Vestibular Neuritis
This type inflames the vestibular nerve, which connects your inner ear’s balance organs to your brain. It typically causes sudden, severe vertigo, the sensation that the room is spinning around you. Nausea, vomiting, difficulty concentrating, and uncontrollable eye movements often accompany the vertigo in the first few days.
The acute phase lasts up to about a week, with symptoms at their most intense. After that, a chronic phase can linger for weeks to several months, bringing milder dizziness, lightheadedness with head movements, and difficulty walking in busy environments. Vestibular neuritis is often confused with labyrinthitis, but there’s a key difference: labyrinthitis involves inflammation of the inner ear structure itself and typically causes hearing changes, while vestibular neuritis affects only the nerve and spares hearing.
Brachial Neuritis
Also called Parsonage-Turner syndrome, brachial neuritis targets the network of nerves running from the neck through the shoulder and into the arm. It strikes with sudden, severe shoulder pain, often starting on one side. The pain is constant, tends to be worse at night, and can radiate down the arm to the forearm and hand. It is not related to position, so changing how you hold your arm doesn’t help.
After one to two weeks of intense pain, weakness begins to set in, sometimes taking days to weeks to appear after the pain starts. You might have trouble lifting your arm, gripping objects, or performing overhead movements. The pain itself is usually self-limiting, resolving within a couple of weeks, but the weakness and numbness take much longer to recover from. One large natural history study found that 89% of patients had full functional recovery by three years. Nerve regrowth typically begins between six months and one year after onset.
What Causes Neuritis
The underlying trigger varies widely, but most cases fall into a few broad categories.
- Infections: Certain bacteria and viruses can provoke an immune response that damages nerves. The most commonly implicated infections include Campylobacter jejuni (a foodborne bacterium), Epstein-Barr virus, cytomegalovirus, varicella zoster (the virus behind chickenpox and shingles), and influenza. These infections don’t attack the nerve directly. Instead, they trigger an immune overreaction in which your body’s defenses mistake nerve tissue for the invading pathogen.
- Autoimmune conditions: In diseases like multiple sclerosis, the immune system attacks myelin throughout the central nervous system. Guillain-Barré syndrome does the same to peripheral nerves. Chronic inflammatory demyelinating polyneuropathy (CIDP) is a longer-lasting version that can occur alongside diabetes, connective tissue disorders, or HIV.
- Nutritional deficiencies: Vitamin B12 plays a critical role in maintaining the myelin sheath. Levels below 260 pmol/L are considered low and are common in older adults, but research suggests that levels around 400 pmol/L may be necessary for optimal nerve function, nearly three times higher than the standard clinical cutoff for deficiency (148 pmol/L). This means you can have “normal” B12 levels on a lab report and still have enough of a shortfall to affect your nerves.
- Cancer-related immune responses: In rare cases, tumors elsewhere in the body produce proteins that resemble molecules on nerve cells. The immune system attacks the tumor but also damages nerves that share those surface markers. This is called paraneoplastic neuropathy.
Neuritis vs. Neuropathy
These terms overlap and are sometimes used interchangeably, but there’s a meaningful distinction. Neuritis specifically refers to nerve inflammation, an active immune or infectious process damaging the nerve. Neuropathy is a broader term for any nerve damage or dysfunction, including damage from diabetes, toxins, compression, or inherited conditions.
In practice, the difference shows up in how the condition behaves. Inflammatory neuritis tends to come on faster, sometimes within days, and often responds to treatments that calm the immune system. Chronic neuropathy from conditions like type 2 diabetes or genetic disorders develops over months to years and is more likely to be permanent. Neuropathy can also alter pain signaling in ways that make nerves fire pain signals on their own or respond to light touch with disproportionate pain, something that typically worsens over time rather than resolving.
How Neuritis Is Treated
Treatment depends on the type and severity. For many forms of inflammatory neuritis, the first-line approach is high-dose steroids given for three to five days to suppress the immune attack. In optic neuritis, this can speed visual recovery, though some doctors opt to observe without treatment since many cases improve on their own. When neuritis is tied to an autoimmune condition like MS, a slower, longer course of anti-inflammatory medication may be needed to prevent recurrences.
If steroids don’t work, other immune-suppressing strategies come into play. Plasma exchange, which filters harmful antibodies out of the blood, is one option. Intravenous immunoglobulin, a concentrated dose of antibodies from donated blood, is another. For neuritis caused by nutritional deficiency, correcting the underlying shortage, particularly B12, can halt further nerve damage and allow some recovery.
Pain management plays a significant role regardless of the cause. The intense pain of brachial neuritis, for example, often requires medication in the first weeks even though it eventually resolves on its own. Vestibular neuritis may involve vestibular rehabilitation therapy, a form of physical therapy designed to retrain your brain’s balance system.
Recovery and Nerve Regeneration
The timeline for recovery depends on whether the myelin sheath alone was damaged or the underlying nerve fiber was also destroyed. When only myelin is affected, the nerve can often repair itself relatively quickly, over weeks to months. When the axon is damaged, regrowth proceeds at roughly 1 to 3 millimeters per day. That’s about an inch per month, which means recovery from nerve damage in the shoulder or thigh can take many months simply because the new nerve fiber has a long distance to travel.
Most people with vestibular neuritis recover well, though some experience residual balance issues in challenging environments for months. Optic neuritis generally has a good visual outcome, with most patients regaining useful vision, though subtle color perception changes may persist. Brachial neuritis has a favorable long-term outlook, with the vast majority regaining function within three years, though the early months can be frustrating as you wait for reinnervation to begin.
Age, overall health, the severity of the initial damage, and how quickly treatment begins all influence the final outcome. Nerves that are repeatedly inflamed, as can happen in relapsing autoimmune conditions, face a harder road to recovery because each episode leaves cumulative damage that becomes increasingly difficult to repair.