COVID-19 can cause knee pain and a range of other joint problems, both during the acute infection and for months afterward. Joint pain ranks among the more common symptoms of COVID, reported by anywhere from about 14% to over 70% of patients depending on the variant and severity of illness. The mechanisms behind it are more varied than most people realize, spanning the body’s inflammatory response, possible direct viral invasion of joint tissue, post-infectious immune reactions, and even side effects of COVID treatment itself.
How Common Is Joint Pain During a COVID Infection
Joint pain shows up frequently in studies tracking COVID symptoms, though the exact numbers vary with the viral variant, the population studied, and how broadly researchers define “joint pain.” In a study of patients with mild-to-moderate COVID, about 14% reported polyarthralgia, which is pain in multiple joints at once. That same study found that roughly 72% of patients experienced at least one type of pain syndrome, with muscle pain and headache each affecting about half of participants.1PubMed Central. Insight into pain syndromes in acute phase of mild-to-moderate COVID-19: Frequency, clinical characteristics, and associated factors A separate study focused on the Delta variant found much higher rates: about 71% of patients reported joint pain specifically, alongside muscle pain in roughly 80% and headache in 77%.2Frontiers in Pain Research. Clinical manifestations of pain in patients suffering from COVID-19 infected with Delta variant of SARS-Cov-2
A third study looking at hospitalized patients found that pain was the chief complaint in nearly 47% of cases, and among those reporting pain, about 69% described a combination of muscle and joint pain.3PubMed Central. Clinical presentations of pain in patients with COVID-19 infection The wide spread in these numbers reflects real differences between variants and between mild outpatient cases and severe hospitalized ones, but the consistent thread is that joint pain is not a rare or unusual COVID symptom. It sits alongside fatigue, fever, and cough as one of the complaints doctors hear most often.
Why the Virus Affects Your Joints
There is no single explanation for COVID-related joint pain. Instead, several pathways overlap, and different patients may be affected by different combinations of them.
The most widespread mechanism is the body’s own inflammatory response. When the immune system detects the virus, it releases signaling molecules called cytokines in large quantities. Among these, IL-6 plays a central role, driving both the fever and the widespread aching that many people experience.4PubMed Central. Cytokine Storm in COVID-19: Exploring IL-6 Signaling and Cytokine-Microbiome Interactions as Emerging Therapeutic Approaches In severe cases, cytokine release can spiral into a “cytokine storm” that damages tissues far beyond the lungs, including joint linings.5PubMed Central. Cytokine release syndrome in severe COVID-19: interleukin-6 receptor antagonist tocilizumab may be the key to reduce mortality This is the same reason your knees, shoulders, and back can ache terribly during a bad flu; the inflammation is systemic, and joints are particularly sensitive to it.
A more direct route has also been investigated: can the virus actually get into joint fluid? The answer appears to be “sometimes, but rarely.” A study examining knee joint fluid from five COVID-positive patients with acute knee arthritis found viral RNA in the synovial fluid of only one of them.6PubMed. Examination of SARS-CoV-2 RNA in joint synovial fluid of patients with COVID-19 and acute knee arthritis A cadaver study looking at knee tissue from people who died of COVID found no viral RNA in any of the knee samples, despite the virus being present in the throat.7PubMed. SARS-CoV-2 in the knee joint: a cadaver study The receptor the virus uses to enter cells, ACE2, is present in the synovial tissue that lines joints, which in theory gives the virus a way in.8The Journal of Rheumatology. Angiotensin-converting Enzyme 2, a SARS-CoV-2 Receptor, Is Upregulated by Interleukin 6 through STAT3 Signaling in Synovial Tissues But based on the evidence so far, direct viral invasion of joints is probably a rare event. Most COVID-related joint pain appears to be driven by the immune system rather than the virus physically colonizing joint tissue.
There is also emerging interest in how tiny blood vessels in and around joints are affected. Research has found increased markers of microthrombosis and blood vessel dysfunction in joint tissues after COVID, suggesting that damage to the small blood vessels supplying cartilage and bone could contribute to joint pathology over time.9Osteoarthritis and Cartilage. Microvascular endothelial dysfunction in SARS-CoV-2-induced osteoarthritis and post-COVID joint pathologies
Reactive Arthritis After Recovery
Some people develop joint inflammation not during their COVID infection but days to weeks after it. This pattern, called reactive arthritis, is a well-known phenomenon with many infections. The immune system, primed by the virus, continues to attack tissues even after the virus is gone. With COVID, reactive arthritis typically appears an average of about three weeks after the initial infection, though the range spans from roughly one week to nearly seven weeks.10PubMed Central. Reactive arthritis following COVID-19 current evidence, diagnosis, and management strategies
The pattern tends to favor the lower limbs. A narrative review of published cases found that the most common presentation was pain and swelling in a few large joints, with knees and ankles being frequent targets.11PubMed Central. Reactive arthritis occurring after COVID-19 infection: a narrative review The good news is that COVID-triggered reactive arthritis usually resolves. In a review of 54 cases, symptoms cleared within days to weeks in all patients, and at the last follow-up, everyone was either asymptomatic or minimally symptomatic with no additional treatment needed.10PubMed Central. Reactive arthritis following COVID-19 current evidence, diagnosis, and management strategies That said, reactive arthritis can still be alarming when it hits. Waking up with a swollen, painful knee two or three weeks after testing positive for COVID, at a point when you thought you were done being sick, catches people off guard.
Long COVID and Persistent Joint Pain
For some people, joint pain does not resolve in days or weeks. It becomes part of the long COVID picture, persisting for months. A large multicenter study of nearly 2,000 hospitalized COVID survivors found that about 45% still had musculoskeletal pain roughly eight months after discharge, and three-quarters of those cases were entirely new pain that did not exist before their infection.12PubMed. Prevalence and risk factors of musculoskeletal pain symptoms as long-term post-COVID sequelae in hospitalized COVID-19 survivors: a multicenter study A systematic review found the prevalence of joint pain after COVID ranged from 2% to 65% depending on the study, measured anywhere from four weeks to twelve months out.13PubMed Central. Post-Acute COVID-19 Joint Pain and New Onset of Rheumatic Musculoskeletal Diseases: A Systematic Review
A meta-analysis tried to pin down more consistent numbers and estimated that about 18% of people continued to report joint pain for up to a year after their acute infection resolved, with a similar 18% reporting persistent muscle pain and about 17% reporting general body pain.14PubMed. Consistency of inconsistency in long-COVID-19 pain symptoms persistency: A systematic review and meta-analysis That roughly one-in-five figure is striking. It means joint pain is not a fringe long COVID symptom but one of the more common lasting complaints, right alongside fatigue and brain fog in terms of how often it shows up in follow-up surveys.
The Nerve Pain Component
Not all post-COVID joint pain is purely inflammatory. Some of it has a neuropathic component, meaning the nervous system itself is generating or amplifying pain signals. A study of post-COVID patients using validated pain questionnaires found that the knee was one of the most commonly affected areas, with about 12% of participants reporting knee pain in the post-COVID period. Both low back pain and knee pain were more common among patients who scored positive on neuropathic pain scales.15PubMed Central. Neuropathic pain in patients with post-COVID-19 This matters practically because neuropathic pain responds to different treatments than inflammatory pain. Standard anti-inflammatory drugs may not help much if the nervous system is misfiring, and recognizing the neuropathic component can steer treatment in a more effective direction.
When COVID Triggers Autoimmune Arthritis
Beyond the temporary reactive arthritis that resolves on its own, there is a more concerning possibility: COVID may trigger lasting autoimmune joint disease in some people. Case reports and small series have documented new-onset rheumatoid arthritis developing after COVID infection in people who had no prior history of the condition.16PubMed Central. COVID-19-Induced Rheumatoid Arthritis: Case Series and Systematic Review of the Literature The systematic review that identified these cases found a pattern suggesting genetic predisposition plays a role, meaning the virus may act as a trigger that tips the immune system into autoimmunity in people already at higher risk. Fibromyalgia and inflammatory arthritis have also been reported as new diagnoses after COVID.13PubMed Central. Post-Acute COVID-19 Joint Pain and New Onset of Rheumatic Musculoskeletal Diseases: A Systematic Review
The evidence here is still mostly at the case-report level, and it is worth keeping perspective: viruses have long been suspected of triggering autoimmune conditions in susceptible individuals. Epstein-Barr virus, parvovirus B19, and hepatitis C have all been linked to new-onset rheumatoid arthritis over the years. COVID is not unique in this respect, but the sheer number of infections worldwide means even a rare complication affects many people in absolute terms.
Steroid-Related Bone Damage
One joint complication from the pandemic has little to do with the virus itself and everything to do with how severe cases were treated. Corticosteroids became a standard therapy for serious COVID-19 because they dampen the dangerous inflammatory response in the lungs. But steroids carry a well-known risk of osteonecrosis, a condition where bone tissue dies because its blood supply is disrupted. The hip is the most commonly affected joint, though knees and shoulders can also be involved.
A retrospective analysis of patients who developed hip osteonecrosis after COVID found that steroid doses varied widely, and the condition emerged even at relatively modest cumulative doses in some cases.17PubMed Central. Outcomes of Hip Avascular Necrosis Following COVID-19 Infection: A Retrospective Analysis of Hips With Minimum Two-Year Follow-Up Because millions of people were treated with steroids for COVID over the past several years, clinicians expect osteonecrosis cases linked to that treatment to continue surfacing for years to come.18Hip & Pelvis. Osteonecrosis following Steroid Therapy in COVID-19 Patients: An Outlook on the Emerging Problem If you received steroid treatment for COVID and later develop deep, persistent pain in a hip or knee that worsens with weight-bearing, this is something to flag with your doctor, since early diagnosis of osteonecrosis can change outcomes.
Impact on People With Existing Joint Conditions
People who already live with conditions like rheumatoid arthritis, lupus, or other autoimmune joint diseases face a double challenge. Getting COVID often triggers a flare of their underlying condition. A prospective study found that 41% of patients with existing autoimmune rheumatic diseases reported a disease flare after their COVID infection, and their overall self-reported disease activity was worse than it had been before they got sick.19PubMed Central. DMARD disruption, rheumatic disease flare, and prolonged COVID-19 symptom duration after acute COVID-19 among patients with rheumatic disease: A prospective study Part of the problem is that COVID infection often disrupts the medications these patients rely on. Many people paused or stopped their disease-modifying drugs during the acute illness, either on medical advice or because they were too sick to keep up their regimen. That interruption alone can be enough to trigger a flare that then takes weeks or months to bring back under control.
The Gut Connection
One of the less obvious pathways linking COVID to joint pain runs through the gut. COVID is known to disrupt the balance of bacteria in the intestines, and an imbalanced gut can become more permeable. When gut bacteria and their byproducts leak into the bloodstream, they can provoke inflammation throughout the body, including in the joints.20Journal of Microbiota. The Interplay of Microbiota, Long COVID, and Musculoskeletal Pain: A Narrative Review This “gut-joint axis” is already a recognized factor in conditions like spondyloarthritis, and researchers are now exploring whether COVID’s disruption of the microbiome helps explain why musculoskeletal symptoms persist in long COVID even after the virus is cleared. It is early-stage research, but it opens up the possibility that supporting gut health could eventually become part of managing post-COVID joint pain.
Treatment Approaches
There is no single COVID-specific joint pain treatment, which reflects the fact that no single mechanism produces the symptom. In practice, management follows the pattern of the underlying problem. For straightforward inflammatory joint pain during or shortly after COVID, the standard tools apply: nonsteroidal anti-inflammatory drugs like ibuprofen and naproxen, acetaminophen for pain relief, and short courses of corticosteroids for more intense flares. For cases where inflammatory arthritis develops and persists, rheumatologists have reached for the same medications used in autoimmune arthritis more broadly, including methotrexate, hydroxychloroquine, and biologic agents.21American Journal of Case Reports. Inflammatory Arthritis After COVID-19: A Case Series
Physical therapy has shown promise for patients whose knee pain becomes a persistent long COVID issue, though the picture is complicated by post-exertional symptom exacerbation, a hallmark of long COVID where overdoing activity causes a setback. A case report of a patient with bilateral knee pain and long COVID documented meaningful improvement in function and pain after eight weeks of guided physical therapy, but also noted a relapse of post-exertional symptoms.22Orthopaedic Physical Therapy Practice. Physical therapy management of a patient with bilateral knee pain and Long Covid: a case report Therapists working with long COVID patients have learned to use a pacing approach, gradually increasing activity while monitoring for setbacks rather than pushing through pain the way traditional rehab programs might.
Joint Problems in Children
Adults are not the only ones affected. Children can develop musculoskeletal symptoms after COVID, sometimes as part of the multisystem inflammatory syndrome in children (MIS-C) and sometimes independently. Arthritis and muscle inflammation have both been documented in pediatric patients.23PubMed Central. COVID-19 musculoskeletal involvement in children Reports include toddlers presenting with a limp and joint effusion linked to COVID-associated transient synovitis, a temporary inflammation of the hip joint that is more commonly triggered by other viruses.24JACEP Open. A toddler with transient synovitis and COVID‐19 infection Most pediatric cases of COVID-related joint inflammation resolve with rest and anti-inflammatory medications. However, at least one case report documented an 11-year-old girl who developed chronic arthritis following MIS-C, still showing signs of joint inflammation months later despite steroid treatment.25The Brazilian Journal of Infectious Diseases. Chronic arthritis related to SARS-CoV-2 infection in a pediatric patient: A case report Persistent limping, joint swelling, or morning stiffness in a child who recently had COVID warrants medical evaluation.
Vaccine-Related Joint Symptoms
People sometimes wonder whether joint pain after vaccination represents the same kind of problem as joint pain after COVID itself. New-onset joint symptoms have been reported following COVID vaccination, with one systematic review of case reports finding that about 64% of affected patients developed symptoms after the first dose and two-thirds did so within the first week. Most cases involved multiple joints, and about 27% of patients fully recovered with no relapse within a few months of follow-up.26PubMed Central. New-Onset Arthritis Following COVID-19 Vaccination: A Systematic Review of Case Reports These are case reports, not population studies, so they tell us the phenomenon exists without telling us how common it is in the broader vaccinated population. The immune activation from a vaccine is far smaller than from actual infection, and the overall risk profile remains heavily in favor of vaccination, but the observation reinforces the idea that the immune response to SARS-CoV-2 proteins, whether from infection or from a vaccine, can sometimes spark joint inflammation in susceptible individuals.