What You Should Know About Reactive Arthritis. 

 April 3, 2024

By  Linda Rook

inflammation of the knee


Reactive arthritis, previously known as Reiter's syndrome, is a type of rheumatic disease with complex origins. It falls under the category of rheumatoid arthritis, an inflammatory condition that can develop in your joints, eyes, and urinary tract.

Reactive arthritis usually occurs following an infection that passes through your gut, manifesting several weeks to months later.

This condition typically affects young adults, more commonly boys than girls, with genetics playing a significant role in its development.

Understanding reactive arthritis.

Reactive arthritis is a type of inflammatory arthritis linked to both infections and autoimmune responses in the body. It falls under the rheumatoid arthritis category, affecting joints as well as other organs like the eyes and urinary tract. While the classic symptoms of reactive arthritis include arthritis, urethritis, and conjunctivitis, it can appear differently in each person, ranging from mild joint discomfort to severe inflammation with pain and swelling.

Additional symptoms like skin lesions, mucosal ulcers, and enthesitis further complicate its diagnosis and management. Genetic predisposition and environmental triggers interact to cause reactive arthritis, with infections, especially bacterial ones, being the most common triggers.

The main cause of reactive arthritis is infection. Certain bacteria, like Chlamydia trachomatis, have been found to trigger an abnormal immune response leading to joint inflammation and other systemic symptoms. These bacteria can provoke inflammatory reactions in your body genetically liable to reactive arthritis. The exact mechanisms through which Chlamydia trachomatis triggers this condition are still being studied, with theories including molecular mimicry and abnormal immune responses. 

Chlamydia Trachomatis: A Leading Culprit in Reactive Arthritis.

1.Chlamydia trachomatis: a type of bacteria that causes a sexually transmitted infection called chlamydia, is a common cause of reactive arthritis. This condition occurs when the immune system reacts to the infection by attacking not only the genital area but also the joints, leading to joint pain and swelling. 

Chlamydia trachomatis, or genital disease.

Although not everyone with a chlamydia infection develops reactive arthritis, it is essential to consider these bacteria when evaluating patients with joint symptoms after a genital infection. Research is still ongoing to understand how Chlamydia trachomatis causes reactive arthritis, but one theory suggests that the bacteria's proteins may resemble the body's own proteins found in joints, leading to an autoimmune response attacking the joints.

2.Pathogenesis: When a person gets a Chlamydia infection, it can lead to reactive arthritis, where the body's immune system mistakenly attacks the joints. This happens because the bacteria look similar to substances found in the joints, causing the immune system to start attacking the joints. The bacteria can also hide from the immune system, making the inflammation in the joints last for a long time.

Reactive arthritis caused by Chlamydia infection usually shows up as joint pain in a few large joints like knees, ankles, and wrists. It happens weeks to months after the initial infection. Along with joint pain, people may also have issues like pain when peeing, eye redness, and other symptoms. However, not everyone will have all these symptoms. Because there can be a variety of symptoms, a doctor needs to suspect this condition and test for Chlamydia in patients with similar symptoms.

4.Diagnostic Considerations:
When trying to figure out if Chlamydia is causing reactive arthritis, doctors need to do a thorough evaluation including asking about your medical history, doing a physical exam, and running some tests. These tests may check for specific antibodies related to Chlamydia and may also look for Chlamydia DNA in joint fluid or tissue. Doctors will also need to make sure there isn't another reason for the arthritis before giving a proper diagnosis.

5.Treatment and management
Treatment for Chlamydia-related arthritis involves taking antibiotics like azithromycin or doxycycline to get rid of the infection. Nonsteroidal anti-inflammatory drugs can be used to reduce joint pain and swelling. In severe cases, special drugs may be needed to prevent long-term damage to the joints.

Other Infections That Can Cause Reactive Arthritis.

Apart from Chlamydia trachomatis, other germs like bacteria, viruses, and parasites can also trigger reactive arthritis. These germs can cause an unusual immune response that leads to joint swelling and other symptoms of reactive arthritis. Understanding these infection triggers is important for diagnosing and treating the condition effectively.

1. Salmonella. 

2. Shigella.

3. Campylobacter.

4. Yersinia. 

5. Viral infection.

6. Pathogenic Infections.


Clinical Appearances and Diagnosis

The clinical appearances of reactive arthritis are varied and include joint inflammation that arises from an infection elsewhere in the body. Although the traditional triad of symptoms—conjunctivitis, arthritis, and urethritis—offers a framework for diagnosis, the condition frequently manifests in a wider range of ways, making diagnosis difficult but necessary for effective treatment.

1. Joint Involvement: The main cause of reactive arthritis is arthritis, which usually shows as asymmetric Oligoarthritis affecting the lower limbs. Joint pain, swelling, and stiffness are the most common symptoms, and large joints like the knees, ankles, and wrists are frequently affected. 

2. Urethritis: Usually seen in males, urethritis is found to have inflammation of the urethra and is a typical distinction of reactive arthritis. Symptoms of urethritis can include frequent urination, dysuria, and urethral discharge. Although it affects men more frequently, female patients can also get urethritis, but it does so less frequently.

3. Conjunctivitis: Another defining mark of reactive arthritis is conjunctivitis or inflammation of the conjunctiva. Usually, it manifests as a bilateral conjunctival injection that has no puss and is accompanied by mild discomfort and photophobia. y goes away on its own, topical lubricants or anti-inflammatory eye solutions can help with symptoms.

4. Other Conditions: Reactive arthritis can present with a range of other conditions to the conventional three above could also include mouth ulcers, nail alterations, and mucocutaneous lesions such keratoderma blennorrhagias and circinate balanitis. Even though they are less frequent, these extra symptoms might offer crucial hints for the diagnosis of reactive arthritis, especially in cases when the patient has unusual symptoms.

5. Diagnosis: A combination of imaging investigations, laboratory testing, and clinical examination is used to diagnose reactive arthritis. To start a diagnosis the medical team may need a comprehensive medical history that includes a complete examination of symptoms and possible exposures to viral triggers.  A physical examination may find symptoms such as enthesitis, and asymmetric Oligoarthritis.

6.Laboratory Investigations: Testing in the lab can help rule out alternative causes of joint inflammation and confirm the diagnosis of reactive arthritis. To determine the underlying infectious cause, serologic testing for particular infections, such as Chlamydia trachomatis, may be carried out. 

MRI scan

7. Imaging Studies: This can look for signs of joint inflammation, synovitis, and structural damage, imaging studies such as X-rays, ultrasounds, and magnetic resonance imaging (MRI) may be carried out.

8. Differential Diagnosis:
To accurately diagnose reactive arthritis, other possible causes of joint inflammation, both infectious and non-infectious, must be carefully taken into account. Reactive arthritis can have symptoms that are similar to those of other conditions such as psoriatic arthritis, ankylosing spondylitis, and rheumatoid arthritis. These conditions need to be ruled out with the right diagnostic testing.

Treatment Strategies.

Reactive arthritis treatment attempts  to find the underlying infection or immune response, reduce inflammation, and relieve symptoms. Depending on the severity of the condition in each person, treatment plans usually combine pharmaceutical medications, supportive care, and focused interventions.

1. Antibiotic Therapy: The purpose of antibiotic therapy is to eliminate the underlying infection and stop it from spreading, which will lessen the likelihood of recurring episodes and inflammatory reactions.

2. NSAIDs, or nonsteroidal anti-inflammatory drugs: these could be Ibuprofen, naproxen, and indomethacin are a few examples of nonsteroidal anti-inflammatory medicines NSAIDs that are frequently used to treat reactive arthritis-related joint pain, swelling, and stiffness. 


3. DMARDs, or disease-modifying antirheumatic medications: Disease-modifying antirheumatic medications (DMARDs) however may be taken into consideration in situations of severe or resistant arthritis to decrease the underlying immune response and avoid long-term joint damage. DMARDs such as methotrexate, hydroxychloroquine, and sulfasalazine are frequently used in the treatment of reactive arthritis.

4. Biologic medicines: In situations of severe or stubborn  arthritis that do not respond to traditional DMARD therapy, biologic medicines, including interleukin (IL) inhibitors and tumour necrosis factor (TNF) inhibitors, may be prescribed

5. Physical Therapy:
By enhancing joint function, strength, and mobility, physical therapy is essential to the management of reactive arthritis. Manual therapy such as stretches, and therapeutic exercises can assist increase the range of motion, lessen discomfort, and improve general physical function.

7. Psychosocial Support: Patients who are dealing with the social, emotional, and physical difficulties brought on by reactive arthritis may find great assistance from psychosocial resources, such as counselling and support groups. Anxiety, despair, and social isolation that are frequently felt by people with chronic inflammatory illnesses, can be lessened by promoting open communication, offering emotional support, and putting patients in touch with community-based resources.


This section I will explore the various manifestations that patients may experience:

Joint Pain:

1.    Intensity: The hallmark symptom of infectious arthritis is often severe joint pain, which can range from mild discomfort to debilitating agony. The pain may be constant or worsen with movement, weight-bearing, or palpation of the affected joint.

2.    Location: The site of joint pain depends on the specific joint(s) affected by the infection. Commonly involved joints include the knee, hip, shoulder, wrist, and ankle. In some cases, multiple joints may be affected simultaneously, particularly in disseminated infections.

Joint Swelling and Warmth:

1.    Swelling (Effusion): Infectious arthritis typically leads to the accumulation of fluid within the affected joint, resulting in visible swelling or fullness around the joint. The degree of swelling can vary depending on the severity of inflammation and the extent of joint involvement.

left knee inflamed and painful.

2.    Warmth: Inflammation within the joint often produces localized heat or warmth, which can be felt upon touching the affected area. This increased temperature is a result of increased blood flow to the inflamed joint as part of the body's immune response.

Limited Range of Motion:

1.    Stiffness: Infectious arthritis can cause stiffness in the affected joint, resulting in reduced flexibility and mobility. Patients may experience difficulty moving the joint through its full range of motion, particularly in the presence of significant swelling and pain.

2.    Functional Impairment: As the inflammation progresses, the joint's limited range of motion may significantly impair daily activities such as walking, climbing stairs, or performing tasks that require manual dexterity. Severe cases may render the joint immobile.


Systemic Symptoms:

1.    Fever: Many individuals with infectious arthritis develop fever, which is typically low to moderate-grade but may be higher in severe cases or in the presence of systemic infection. Fever is an indication of the body's systemic inflammatory response to the infection.

2.    Chills: Patients may experience episodes of chills or rigors, often accompanying fever, as the body attempts to raise its core temperature to combat the infection. Chills are a common symptom of systemic inflammatory conditions.

Skin Changes:

1.    Redness: Inflammation of the joint may lead to redness or erythema over the affected area. The skin surrounding the joint may appear flushed or discoloured due to increased blood flow and vasodilation in response to inflammation.

2.    Warmth: In addition to warmth localized to the joint, the surrounding skin may feel warm to the touch due to the inflammatory process. This warmth is a result of increased blood flow to the area, contributing to the sensation of heat.

Rash on the arm or psoriasis.

Other Symptoms:

1.    Fatigue: Systemic infection and inflammation associated with infectious arthritis can cause fatigue or malaise, which may persist even after the joint symptoms improve. Fatigue is a common nonspecific symptom of many infectious and inflammatory conditions.

2.    Generalized Symptoms: Depending on the underlying cause of the infectious arthritis, patients may experience additional symptoms such as skin rash, oral ulcers, genital lesions, respiratory symptoms, or gastrointestinal complaints. These symptoms may provide clues to the specific infectious agent involved.


Diagnosing and treating reactive arthritis, is a complicated inflammatory disease, brought on by infections elsewhere in the body, and can be difficult for medical professionals to diagnose.

Reactive arthritis is mainly caused by a complex interaction between your immune system, genetics, and viral infections.   When it comes to diagnostic examination and the treatment, it includes antibiotic medication where necessary, the identification of particular infectious triggers is critical.

Reactive arthritis is still a mysterious illness, due to its complexity.  More studies need to be done before clarifying the underlying causes, improve diagnostic techniques, and create more potent treatments. 

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Linda Rook

Linda is now retired and has suffered from Osteoarthritis for about 40+ years.  She struggled with her weight until she found the correct one that also helped with her arthritic pain.  Linda was in terrible pain until the physician thought her right hip needed replacement. 

Now Linda has an artificial right hip, which has left her with the left leg shorter than the right.  Therefore, her spine is now wonky, and has arthritis of the lower back, also it seems to be going all over the body, her pain is now in the knees, elbow, wrist, fingers and both hips.

Linda now spends her days writing information to help others with the same conditions, so they do not suffer like Linda.

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