By Lana Barhum 

 Medically reviewed by David Ozeri, MD

Multiple sclerosis (MS) and reactive arthritis are conditions that cause joint pain and swelling. MS is an autoimmune disease that occurs when the immune system malfunctions and starts to attack healthy tissues. MS will target the brain and spinal cord, attacking the myelin sheath—the protective coating surrounding nerve fibers.

Researchers believe that reactive arthritis is also an autoimmune disorder triggered by an infection that induces an immune system response.1 Bacteria can travel from the site of infection through the bloodstream to the synovial tissue (lining of the joints), leading to the development of reactive arthritis.

MS and reactive arthritis might share similar symptoms and, possibly, immune system processes. But they are two very different conditions.

This article covers the similarities and differences between MS and reactive arthritis, along with diagnosis, treatment, and prevention.

AsiaVision / Getty Images

Symptoms

The main difference between MS and reactive arthritis is the areas of the body affected. With MS, there is damage to the brain and spinal cord. In reactive arthritis, the joints are targeted.

People with MS will experience different types of pain, including joint and back pain. But most of the pain they experience is stabbing pain that results from faulty nerve signals due to MS lesions on the brain and spinal cord.2

There are some additional symptom similarities between the two conditions, although many are different. Symptoms of MS and reactive arthritis include:31

Multiple Sclerosis

Dysesthesia (squeezing sensation around the torso)

Gait (walking) troubles

Muscle spasms

Fatigue

Muscle weakness

Numbness and tingling

Vertigo and dizziness

Bladder and bowel problems

Sexual dysfunction

Eye inflammation

Joint and muscle pain

Reactive Arthritis

Joint pain and swelling

Sacroiliitis (inflammation of the  sacroiliac joints) leading to buttock and low back pain

Urinary problems

Eye inflammation

Skin rash

Heel pain and heel spurs

Spondylitis (spine inflammation)

Tendinitis (tendon swelling)

Enthesitis (swelling of the tendons and ligaments in the areas where they meet bone)

Causes

Much like other autoimmune conditions, there are no definitive causes for MS and reactive arthritis.

One popular theory among researchers is that some types of bacteria or viruses might trigger changes in the immune system that cause it to malfunction.4 This is often the case for people who have mutated genes that make them susceptible to autoimmune disorders.

Multiple Sclerosis

In people with MS, your malfunctioning immune system attacks the myelin sheath. With that damage, nerve fibers become exposed, causing the messages that travel along those nerves to be slowed or blocked.5

Researchers don't know why this occurs or why it develops in some people and not others. What they do know, however, is that a combination of genetics and environmental triggers (such as chronic stress, trauma, and illness) might be to blame.

MS is also linked to certain risk factors, including:

• Age: While anyone can get MS, it is commonly diagnosed between the ages of 20 and40.5

• Sex: Females are 3 times more likely to have MS than males.6

• Some infections: These include Epstein-Barr, the virus responsible for infectious mononucleosis, which might trigger MS to develop.

• Other autoimmune diseases: If you have one or more autoimmune diseases, your risk for MS increases.

• Smoking: People who smoke have a higher risk for MS compared to nonsmokers.7

People who are White are more often diagnosed with MS than people of other races.8

Reactive Arthritis

A specific underlying cause of reactive arthritis is unknown. However, researchers believe that the condition is linked in some way to genetic predisposition. This is because many people who get the condition will test positive for HLA-B27.1

HLA-B27 is a genetic marker linked to a group of disorders known as spondyloarthritis, types of inflammatory arthritis that affect the spine and cause low back and sacroiliac (SI) joint pain.

Reactive arthritis tends to occur after exposure to specific types of bacteria, especially those that lead to sexually transmitted infections (STIs) and gastrointestinal (GI) infections. Examples of such bacteria are:1

• Campylobacter

• Chlamydia

• Salmonella

• Shigella

• Yersinia

Reactive arthritis might also be triggered after a SARS-CoV-2 infection causing COVID-19.9 There are numerous individual cases in medical literature citing examples of people who develop reactive arthritis while recovering from COVID-19 or after they have recovered.

Diagnosis

Diagnosing MS and reactive arthritis is complicated because there is no single test to confirm either condition. In order to determine the cause of your symptoms, your healthcare provider will gather information based on symptoms, medical and family history, lab work, and imaging.

Multiple Sclerosis

In diagnosing MS, your healthcare provider will start with your medical history and a physical examination. Your medical history will include past and present symptoms, family history, and any conditions you have or previously had.

A physical exam will be performed. A neurological exam for MS generally includes an assessment of vision, facial sensations, strength, swallowing reflexes, walking, and balance.10

Providing a medical history and having a neurological exam are generally enough to diagnose MS.10 Other tests might be done to confirm the diagnosis or to rule out other possible causes of symptoms.

Additional testing might include:

• Blood work: While there is not just one test to confirm MS, blood tests might be able to rule out other conditions that cause similar symptoms, such as rheumatoid arthritis or reactive arthritis.

• Spinal tap: Also called a lumbar puncture, this test removes a small amount of cerebrospinal fluid from the spinal canal for lab testing. The fluid can show abnormalities in antibodies specific to MS. It can also rule out infections and other conditions that cause similar symptoms.

• Magnetic resonance imaging (MRI): An MRI can reveal MS lesions on the brain and spinal cord.

• Evoked potential tests: These tests look for reduced electrical signals from the nerves in response to stimuli. With this test, your healthcare provider looks to see how quickly information travels on nerve pathways. Signals will be slower or blocked if there is damage to those pathways.

MS is a progressive condition, which means it will get worse over time. You should reach out to your healthcare provider as soon as you start experiencing symptoms. An early diagnosis means early treatment, and both improve the chance of slowing down the disease.

Reactive Arthritis

Much like MS, more than one test is needed to diagnose or confirm reactive arthritis. A diagnosis can be difficult because of the way symptoms present and the timeline of those symptoms.

Symptoms of reactive arthritis can last anywhere from three to 12 months and can come and go.1 For 30%–50% of people who develop reactive arthritis, the condition can return and become chronic (lasting more than six months).

A diagnosis becomes less complicated if a person experiences eye, joint, and urinary tract symptoms all at once or close together in time.

In determining the cause of your symptoms, your healthcare provider may use the following:

• Perform a physical exam of your joints, spine, and eyes

• Ask about your medical history, including recent infections or illnesses

• Request blood work for infections and arthritis conditions

• Request imaging, including X-rays and MRI

• Request a urinalysis if you have urinary symptoms

• Perform a joint aspiration to rule out infections or gout

If you develop joint or low-back pain a few weeks after experiencing an infection, reach out to your healthcare provider. It is important to get treatment right away so that reactive arthritis does not become chronic and lead to joint damage.

Treatment

MS is a lifelong condition without a cure, but it is treatable. It is possible to slow down its effects and reduce the potential for disease complications. Reactive arthritis, on the other hand, might not return after the initial outbreak, or it may become chronic and eventually cause joint damage.

Multiple Sclerosis

There are many treatment options to help people with MS manage symptoms and slow down disease progression. You should work closely with your healthcare provider to find a treatment plan that works for you and causes the least amount of side effects.

Medicines used to treat MS include:

• Disease-modifying antirheumatic drugs (DMARDs) to slow down the immune system and keep it from attacking myelin

• Beta interferons to ease symptoms and reduce MS flare-ups (periods of increased disease activity and symptoms)

• Medicines like Mavenclad (cladribine) or Tecfidera (dimethyl fumarate) that affect the immune system to reduce symptoms

• Chemotherapy drugs, including Lemtrada (alemtuzumab) and Novantrone (mitoxantrone) to stop your immune system's attacks on the myelin

• Corticosteroids to treat MS flare-ups

• Additional medicines to manage specific symptoms, including fatigue and bladder symptoms

Plasma exchange may be performed for flare-ups that do not respond to corticosteroids. In this procedure, blood is drawn as in a blood donation. The blood cells are returned to you, but the liquid portion of your blood is discarded.

Your healthcare provider might recommend physical therapy to manage MS pain and symptoms. A physical therapist can show you safe ways to keep moving and how to use assistive devices to get around.

Reactive Arthritis

If your healthcare provider can determine a bacterial infection has triggered your reactive arthritis, they might prescribe an antibiotic. The antibiotic prescribed will depend on what type of bacteria is present.

Symptoms of reactive arthritis can be managed with:

• Nonsteroidal anti-inflammatory drugs (NSAIDs): Your healthcare provider might prescribe a strong NSAID, such as a high-dose ibuprofen, to relieve pain and inflammation linked to reactive arthritis.

• Corticosteroid injections into affected joints to reduce inflammation

• Steroid eye drops for eye symptoms

• Steroid creams for skin rashes

If reactive arthritis becomes chronic, your healthcare provider may treat it with a DMARD like Trexall (methotrexate). They might also recommend physical therapy to manage joint pain and stiffness.

Prevention

Autoimmune diseases like MS are generally not preventable. However, it might be possible to prevent reactive arthritis by managing its risk factors.

Multiple Sclerosis

MS generally cannot be prevented as some risk factors for the condition such as age, sex, and genetic predisposition cannot be changed. However, it is possible to reduce your risk by not smoking and managing any other autoimmune conditions you might have.

Reactive Arthritis

Reactive arthritis might be preventable. The most effective way to prevent the condition is to reduce your risk of STIs and GI infections.

STIs are preventable with safe sex practices, including using condoms. To avoid gastrointestinal infections, make sure you practice good hygiene when storing and preparing food.

Summary

Multiple sclerosis and reactive arthritis share some similar symptoms, including joint pain and fatigue, but their similarities stop there.

MS is an aggressive autoimmune disease that, if left untreated, will get progressively worse. Researchers think that reactive arthritis might also be an autoimmune disease because it is triggered by certain types of bacteria that create a response in the immune system leading it to malfunction.

Diagnosing MS or reactive arthritis is sometimes complicated because they share symptoms with other types of autoimmune diseases. You should reach out to your healthcare provider as soon as you start to experience symptoms of either condition.

MS is generally not preventable. However, it is possible to prevent reactive arthritis by managing risk factors for the condition, including those that lead to sexually transmitted infections and gastrointestinal infections.

Sources

National Organization for Rare Disorders. Reactive arthritis.

MS International Foundation. Pain.

National Multiple Sclerosis Society. MS signs and symptoms.

MedlinePlus. Autoimmune disorders.

National Institute of Neurological Disorders and Stroke. Multiple sclerosis: Hope through research.

National Multiple Sclerosis Society. Who gets MS?

Taan M, Al Ahmad F, Ercksousi MK, Hamza G. Risk factors associated with multiple sclerosis: a case-control study in Damascus, Syria. Mult Scler Int. 2021;2021:8147451. doi:10.1155/2021/8147451

National Multiple Sclerosis Society. MS prevalence.

Ono K, Kishimoto M, Shimasaki T, et al. Reactive arthritis after COVID-19 infection. RMD Open. 2020;6(2):e001350. doi:10.1136/rmdopen-2020-001350

National Multiple Sclerosis Society. How MS is diagnosed.

By Lana Barhum
Lana Barhum has been a freelance medical writer since 2009. She shares advice on living well with chronic disease.