Symptoms of JIA are often nonspecific initially, and include lethargy, reduced physical activity, and poor appetite. The first manifestation, particularly in young children, may be limping. Children may also become quite ill, presenting with flu-like symptoms that persist. The cardinal clinical feature is persistent swelling of the affected joint(s), which commonly include the knee, ankle, wrist, and small joints of the hands and feet. Swelling may be difficult to detect clinically, especially for joints such as those of the spine, sacroiliac joints, shoulder, hip, and jaw, where imaging techniques such as ultrasound or MRI are very useful.

Pain is an important symptom. Morning stiffness that improves later in the day is a common feature (this implies inflammatory-type joint pain versus mechanical-type joint pain). Late effects of arthritis include joint contracture (stiff, bent joint due to fibrosis) and joint damage. Children with JIA vary in the degree to which they are affected by particular symptoms. Symptoms may also differ between sexes, affecting girls and boys differently among different geographic locations. This is predicted to be due to biological differences in different geographic regions. Children may also have swollen joints (inflammatory swelling, or in chronic arthritis due to synovial proliferation and thickening, and periarticular soft-tissue swelling).

Eye disease: JIA is associated with inflammation in the front of the eye (specifically iridocyclitis, a form of chronic anterior uveitis), which affects about one child in five who has JIA, most commonly girls. This complication is usually asymptomatic and can be detected by an experienced optometrist or ophthalmologist using a slit lamp. Later slit lamp features include synechiae. Most children with JIA are enrolled in a regular slit lamp screening program, as poorly controlled chronic anterior uveitis may result in permanent eye damage, including blindness.

Growth disturbance: Children with JIA may have reduced overall rate of growth, especially if the disease involves many joints or other body systems. Paradoxically, individually affected large joints (such as the knee) may grow faster, due to inflammation-induced increased blood supply to the bone growth plates situated near the joints. This can result in leg length discrepancy, and also deformities such as genu valgum. Asymmetrical growth can also affect other bones e.g. discrepancy in digit length. Marked differences in bone age (skeletal maturation) may be seen.

Three types of juvenile arthritis exist—juvenile rheumatoid arthritis (JRA), juvenile chronic arthritis (JCA), and juvenile idiopathic arthritis (JIA), of which JRA is the most common.

JRA again can be divided into three main forms: The classification is based upon symptoms, number of joints involved and the presence of certain antibodies in the blood.

1. Polyarticular arthritis is the first type of arthritis, which affects about 30–40% of children with arthritis and is more common in girls than boys. Typically five or more joints are affected (usually smaller joints such as the hands and feet but many also affect the hips, neck, shoulders and jaw).

2. Oligoarticular (aka pauciarticular) arthritis can be early or late onset and is the second type of arthritis, affecting about 50% of children with juvenile arthritis. This type affects fewer than four joints (usually the large joints such as knees, ankles or wrists) and may cause eye inflammation in girls with positive anti-nuclear antibodies (ANA). Girls younger than eight are more likely to develop this type of arthritis.

3. Systemic disease is the least common form, with 10–20% of children (boys and girls equally) being affected with limited movement, swelling and pain in at least one joint. A common symptom of this type is a high, spiking fever of or higher, lasting for weeks or months, and a rash of pale red spots on the chest, thighs or other parts of the body may be visible.

Pain, which can vary in severity, is a common symptom in virtually all types of arthritis. Other symptoms include swelling, joint stiffness and aching around the joint(s). Arthritic disorders like lupus and rheumatoid arthritis can affect other organs in the body, leading to a variety of symptoms. Symptoms may include:

- Inability to use the hand or walk

- Stiffness, which may be worse in the morning, or after use

- Malaise and fatigue

- Weight loss

- Poor sleep

- Muscle aches and pains

- Tenderness

- Difficulty moving the joint

It is common in advanced arthritis for significant secondary changes to occur. For example, arthritic symptoms might make it difficult for a person to move around and/or exercise, which can lead to secondary effects, such as:

- Muscle weakness

- Loss of flexibility

- Decreased aerobic fitness

These changes, in addition to the primary symptoms, can have a huge impact on quality of life.

In most cases, juvenile arthritis is caused by the body attacking its own healthy cells and tissues, i.e. autoimmunity, causing the joint to become inflamed and stiff. Once the joint has become inflamed and stiff, damage is done to the joint and the growth of the joint may by changed or impaired.

The signs and symptoms of ankylosing spondylitis often appear gradually, with peak onset being between 20 and 30 years of age. Initial symptoms are usually a chronic dull pain in the lower back or gluteal region combined with stiffness of the lower back. Individuals often experience pain and stiffness that awakens them in the early morning hours.

As the disease progresses, loss of spinal mobility and chest expansion, with a limitation of anterior flexion, lateral flexion, and extension of the lumbar spine, are seen. Systemic features are common, with weight loss, fever, or fatigue often present. Pain is often severe at rest but may improve with physical activity, but inflammation and pain to varying degrees may recur regardless of rest and movement.

AS can occur in any part of the spine or the entire spine, often with pain referred to one or the other buttock or the back of the thigh from the sacroiliac joint.

Arthritis in the hips and shoulders may also occur. When the condition presents before the age of 18, it is more likely to cause pain and swelling of large lower limb joints, such as the knees. In prepubescent cases, pain and swelling may also manifest in the ankles and feet where heel pain and enthesopathy commonly develop. Less commonly ectasia of the sacral nerve root sheaths may occur.

About 40% of people with AS will also experience inflammation of the anterior chamber of the eye, causing eye pain, redness, floaters and sensitivity to light. This is thought to be due to the association that both AS and uveitis have with the inheritance of the HLA-B27 antigen.

Inflammation of the prostate occurs with increased frequency in men.

Cardiovascular involvement may include inflammation of the aorta, aortic valve insufficiency or disturbances of the heart's electrical conduction system. Lung involvement is characterized by progressive fibrosis of the upper portion of the lung.

Pain, swelling, or stiffness in one or more joints is commonly present in psoriatic arthritis. Psoriatic arthritis is inflammatory, and affected joints are generally red or warm to the touch. Asymmetrical oligoarthritis, defined as inflammation affecting one to four joints during the first six months of disease, is present in 70% of cases. However, in 15% of cases, the arthritis is symmetrical. The joints of the hand that is involved in psoriasis are the proximal interphalangeal (PIP), the distal interphalangeal (DIP), the metacarpophalangeal (MCP), and the wrist. Involvement of the distal interphalangeal joints (DIP) is a characteristic feature and is present in 15% of cases.

In addition to affecting the joints of the hands and wrists, psoriatic arthritis may affect the fingers, nails, and skin. Sausage-like swelling in the fingers or toes, known as dactylitis, may occur. Psoriasis can also cause changes to the nails, such as pitting or separation from the nail bed, onycholysis, hyperkeratosis under the nails, and horizontal ridging. Psoriasis classically presents with scaly skin lesions, which are most commonly seen over extensor surfaces such as the scalp, natal cleft and umbilicus.

In psoriatic arthritis, pain can occur in the area of the sacrum (the lower back, above the tailbone), as a result of sacroiliitis or spondylitis, which is present in 40% of cases. Pain can occur in and around the feet and ankles, especially enthesitis in the Achilles tendon (inflammation of the Achilles tendon where it inserts into the bone) or plantar fasciitis in the sole of the foot.

Along with the above-noted pain and inflammation, there is extreme exhaustion that does not go away with adequate rest. The exhaustion may last for days or weeks without abatement. Psoriatic arthritis may remain mild or may progress to more destructive joint disease. Periods of active disease, or flares, will typically alternate with periods of remission. In severe forms, psoriatic arthritis may progress to arthritis mutilans which on X-ray gives a "pencil-in-cup" appearance.

Because prolonged inflammation can lead to joint damage, early diagnosis and treatment to slow or prevent joint damage is recommended.

Infectious arthritis is another severe form of arthritis. It presents with sudden onset of chills, fever and joint pain. The condition is caused by bacteria elsewhere in the body. Infectious arthritis must be rapidly diagnosed and treated promptly to prevent irreversible joint damage.

Psoriasis can develop into psoriatic arthritis. With psoriatic arthritis, most individuals develop the skin problem first and then the arthritis. The typical features are of continuous joint pains, stiffness and swelling. The disease does recur with periods of remission but there is no cure for the disorder. A small percentage develop a severe painful and destructive form of arthritis which destroys the small joints in the hands and can lead to permanent disability and loss of hand function.

Symptoms of inflammatory arthritis include stiffness, pain, and swelling of the joints, restricted motions, and reduced physical strength. Other symptoms may include systemic complaints including fatigue.

Inflammation of the cartilage of the ear is a specific symptom of the disease and affects most people. It is present in about 20% of persons with RP at presentation and in 90% at some point. Both ears are often affected but the inflammation may alternate between either ear during a relapse. It is characteristic for the entire outer part of the ear except the earlobe to be swollen, red, or less often purplish, warm and painful to light touch.

The inflammation of the ear usually lasts a few days or more, rarely a few weeks, and then resolves spontaneously and recurs at various intervals. Because of the loss of cartilage, after several flares cauliflower ear deformity may result. The outer part of the ear may be either floppy or hardened by calcifications of the scar tissue that replaces the cartilage. These cauliflower ear deformities occurs in about 10% of persons with RP.

The second most common clinical finding of this disease is joint pain with or without arthritis, after chondritis.

All synovial joints may be affected.

At presentation, around 33% of people have joint symptoms that involve Polyarthralgia and/or polyarthritis or oligoarthritis that affects various parts of the body and often appears to be episodic, asymmetric, migratory and non-deforming. The most common sites of involvement are the metacarpophalangeal joints, proximal interphalangeal joints and knees. After which is followed by the ankles, wrists, metatarsophalangeal joints and the elbows. Any involvement of the axial skeleton is considered to be very rare. Tests for rheumatoid factor are negative in affected persons with RP, unless there is a co-morbidity with RA.

Less often it has been reported that persons may experience arthralgia, monoarthritis, or chronic polyarthritis that mimics rheumatoid arthritis, leading to a difficult diagnosis for this disease. The appearance of erosions and destruction, however, is exceedingly rare and this may point instead to rheumatoid arthritis as a cause.

Diseases and inflammation of tendons have been reported in small numbers of people with RP. During the course of the disease, around 80% of people develop joint symptoms.

There are five main types of psoriatic arthritis:

- Oligoarticular: This type affects around 70% of patients and is generally mild. This type does not occur in the same joints on both sides of the body and usually only involves fewer than 3 joints.

- Polyarticular: This type accounts for around 25% of cases, and affects five or more joints on both sides of the body simultaneously. This type is most similar to rheumatoid arthritis and is disabling in around 50% of all cases.

- Arthritis mutilans (): Affects less than 5% of patients and is a severe, deforming and destructive arthritis. This condition can progress over months or years causing severe joint damage. Arthritis mutilans has also been called chronic absorptive arthritis, and may be seen in rheumatoid arthritis as well.

- Spondyloarthritis (): This type is characterized by stiffness of the neck or the sacroiliac joint of the spine, but can also affect the hands and feet, in a similar fashion to symmetric arthritis.

- Distal interphalangeal predominant (): This type of psoriatic arthritis is found in about 5% of patients, and is characterized by inflammation and stiffness in the joints nearest to the ends of the fingers and toes. Nail changes are often marked.

Spondyloarthropathy or spondyloarthrosis refers to any joint disease of the vertebral column. As such, it is a class or category of diseases rather than a single, specific entity. It differs from spondylopathy, which is a disease of the vertebra itself. However, many conditions involve both spondylopathy and spondyloarthropathy.

Spondyloarthropathy with inflammation is called axial spondyloarthritis. In the broadest sense, the term spondyloarthropathy includes joint involvement of vertebral column from any type of joint disease, including rheumatoid arthritis and osteoarthritis, but the term is often used for a specific group of disorders with certain common features, the group often being termed specifically seronegative spondylarthropathies. They have an increased incidence of HLA-B27, as well as negative rheumatoid factor and ANA. Enthesopathy is also sometimes present in association with seronegative.

Non-vertebral signs and symptoms of degenerative or other not-directly-infected inflammation, in the manner of spondyloarthropathies, include asymmetric peripheral arthritis (which is distinct from rheumatoid arthritis), arthritis of the toe interphalangeal joints, sausage digits, Achilles tendinitis, plantar fasciitis, costochondritis, iritis, and mucocutaneous lesions. However, lower back pain is the most common clinical presentation of the causes of spondyloarthropoathies; this back pain is unique because it decreases with activity.

When monoarthritis is caused by "pseudogout" (calcium pyrophosphate deposition disease, CPPD), the inflammation usually lasts days to weeks, and involves the knees in half of all attacks. Like gout, attacks can occur spontaneously or with physical trauma or metabolic stress. Patients may feel well in between pseudogout attacks, and 5% present with pseudo-rheumatoid symptoms.

Treatments for inflammatory arthritis vary by subtype, though they may include drugs like DMARDs (disease-modifying anti-rheumatic drugs) and tumor necrosis factor inhibitors.

The disorder is more common in older adults. The disease is often occult until crystal deposits are coincidentally detected and diagnosed by a pathologist in various orthopedic specimens. It may be asymptomatic, or it can be associated with osteoarthritis, or it can present as an acute or chronic inflammatory arthritis that causes pain in one or more joints. The white blood cell count is often raised.

The arthritis is usually polyarticular (i.e., it leads to an inflammation of several joints in the body), although it may begin as monoarticular (i.e., confined to just one joint). CPPD crystals tend to form within articular tissues. In theory, any joint may be affected, but statistics show that the knees are the most commonly affected joints, as well as wrists and hips.

In many instances, patients may also have signs of carpal tunnel syndrome. This condition can also be associated with Milwaukee shoulder syndrome.

The following conditions are typically included within the group of "seronegative spondylarthropathies":

Some sources also include Behcet's disease and Whipple's disease.

Systemic JIA is characterized by arthritis, fever, which typically is higher than the low-grade fever associated with polyarticular and a salmon pink rash. It accounts for 10-20% of JIA and affects males and females equally, unlike the other two subtypes of JIA, and affects adolescents. It generally involves both large and small joints. Systemic JIA can be challenging to diagnose because the fever and rash come and go. Fever can occur at the same time every day or twice a day (often in late afternoon or evening) with a spontaneous rapid return to baseline (vs. septic arthritis of continuous fever). The rash often occurs with fever. It is a discrete, salmon-pink macules of different sizes. It migrates to different locations on skin, rarely persisting in one location more than one hour. The rash is commonly seen on trunk and proximal extremities or over pressure areas.

Arthritis is often absent in the first weeks or even 6–8 months into the illness.

Systemic JIA may have internal organ involvement such as hepatosplenomegaly, lymphadenopathy, serositis, hepatitis, or tenosynovitis.

A polymorphism in macrophage migration inhibitory factor has been associated with this condition.

Palindromic rheumatism is a rare type of inflammatory arthritis which causes sudden inflammation in one or several joints, lasts a few hours or up to a few days, and then goes away completely. The problem usually involves 2 or 3 joints, which have onset over hours and last days to weeks, before subsiding. However episodes of recurrence form a pattern, with symptom-free periods between attacks lasting for weeks to months. The large joints are most commonly involved. Constitutionally, there may or may not be a fever, and swelling of the joints. The soft tissues are involved with swelling of the periarticular tissues, especially heel pads and finger pads. Nodules may be found in the subcutaneous tissues.Attacks may become more frequent with time but there is no joint damage after attacks.

It typically affects people between the ages of 20 and 50. One study showed an average age of onset of 49.

Occurs in 5-10% of patients who have psoriasis.Classic presentation involves the DIP(distal inerphalangeal joints).Morning stiffness is present.Deformity of involved joints,dactylitis and nail involvement are common.Well demarcated red plaques with silvery scaling - the classic lesions of psoriasis are seen on the dorsum of the hand.

For a person with arthritis mutilans in the hands, the fingers become shortened by arthritis, and the shortening may become severe enough that the hand looks paw-like, with the first deformity occurring at the interphalangeal and metacarpophalangeal joints. The excess skin from the shortening of the phalanx bones becomes folded transversely, as if retracted into one another like opera glasses, hence the description "la main en lorgnette". As the condition worsens, luxation, phalangeal and metacarpal bone absorption, and skeletal architecture loss in the fingers occurs.

People suffering from sacroiliitis can often experience symptoms in a number of different ways, however it is commonly related to the amount of pressure that is put onto the sacroiliac joint. Sacroiliitis pain is typically axial, meaning that the location of the condition is also where the pain is occurring. Symptoms commonly include prolonged, inflammatory pain in the lower back region, hips or buttocks.

However, in more severe cases, pain can become more radicular and manifest itself in seemingly unrelated areas of the body including the legs, groin and feet.

Symptoms are typically aggravated by:

- Transitioning from sitting to standing

- Walking or standing for extended periods of time

- Running

- Climbing stairs

- Taking long strides

- rolling over in bed

Mortality is increased in people with AS and circulatory disease is the most frequent cause of death. AS patients have an increased risk of 60% for cerebrovascular mortality, and an overall increased risk of 50% for vascular mortality. About one third of those with Ankylosing spondylitis have severe disease, which reduces life expectancy.

As increased mortality in ankylosing spondylitis is related to disease severity, factors negatively affecting outcomes include:

- Male sex

- Plus 3 of the following in the first 2 years of disease:

- Erythrocyte sedimentation rate (ESR) >30 mm/h

- Unresponsive to NSAIDs

- Limitation of lumbar spine range of motion

- Sausage-like fingers or toes

- Oligoarthritis

- Onset <16 years old

Reactive arthritis, also known as Reiter's syndrome, is a form of inflammatory arthritis that develops in response to an infection in another part of the body (cross-reactivity). Coming into contact with bacteria and developing an infection can trigger the disease. By the time the patient presents with symptoms, often the "trigger" infection has been cured or is in remission in chronic cases, thus making determination of the initial cause difficult.

The arthritis often is coupled with other characteristic symptoms; this has been called Reiter's syndrome, Reiter's disease or Reiter's arthritis. The term "reactive arthritis" is increasingly used as a substitute for this designation because of Hans Conrad Julius Reiter's war crimes with the Nazi Party. The manifestations of reactive arthritis include the following triad of symptoms: an inflammatory arthritis of large joints, inflammation of the eyes in the form of conjunctivitis or uveitis, and urethritis in men or cervicitis in women. Arthritis occurring alone following sexual exposure or enteric infection is also known as reactive arthritis. Patients can also present with mucocutaneous lesions, as well as psoriasis-like skin lesions such as circinate balanitis, and keratoderma blennorrhagicum. Enthesitis can involve the Achilles tendon resulting in heel pain. Not all affected persons have all the manifestations.

The clinical pattern of reactive arthritis commonly consists of an inflammation of fewer than five joints which often includes the knee or sacroiliac joint. The arthritis may be "additive" (more joints become inflamed in addition to the primarily affected one) or "migratory" (new joints become inflamed after the initially inflamed site has already improved).

Reactive arthritis is an RF-seronegative, HLA-B27-linked arthritis often precipitated by genitourinary or gastrointestinal infections. The most common triggers are intestinal infections (with "Salmonella", "Shigella" or "Campylobacter") and sexually transmitted infections (with "Chlamydia trachomatis").

It most commonly strikes individuals aged 20–40 years of age, is more common in men than in women, and more common in white than in black people. This is owing to the high frequency of the HLA-B27 gene in the white population. It can occur in epidemic form. Patients with HIV have an increased risk of developing reactive arthritis as well.

A large number of cases during World Wars I and II focused attention on the triad of arthritis, urethritis, and conjunctivitis (often with additional mucocutaneous lesions), which at that time was also referred to as Fiessenger-Leroy-Reiter syndrome.

Enthesitis can assist in differentiating arthritis mutilans' parent condition psoriatic arthritis from rheumatoid arthritis and osteoarthritis, with evidence in plain radiographs (x-rays) and MRI as periostitis, new bone formation, and bone erosions. Dactylitis, spondylitis and sacroiliitis are common with the parent condition psoriatic arthritis, but are not in rheumatoid arthritis. MRI bone edema scores are high in arthritis mutilans and correlate with radiographic measures of joint damage, although they may not correlate with disease activity. A source of significant pain, bone marrow edema (or lesions, using newer terminology), can be detected on MRI or with ultrasonography by signals of excessive water in bone marrow. Specifically, bone marrow edema can be detected within bone on T1-weighted images as poorly defined areas of low signal, with a high signal on T2-weighted fat-suppressed images. Comparatively, with arthritis mutilans in "rheumatoid arthritis", bone marrow edema often involves the bone layer, while the condition as a subtype of "psoriatic arthritis" includes a greater extent of marrow edema, expanding to diaphysis.