Some people experience joint pain after COVID-19 due to a combination of immune system reactions, inflammation, and possible autoimmune responses triggered by the virus. When the body detects the SARS-CoV-2 virus, it releases inflammatory chemicals called cytokines to fight the infection. These cytokines cause inflammation, which can make muscles and joints feel sore, stiff, or painful. This inflammatory response is a key reason why joint pain occurs during and sometimes after the acute phase of COVID-19 infection[1].
The virus itself can also directly affect tissues by attaching to ACE2 receptors, which are present not only in the lungs but also in muscles and nerves. This viral entry can irritate these tissues, contributing to pain and weakness in joints and muscles[1]. In some cases, the inflammation spreads through the bloodstream, causing generalized pain similar to flu-like symptoms.
For many people, joint pain resolves within a few weeks as the infection clears. However, in moderate to severe cases, or when fever and inflammation persist, joint pain can last for one to two weeks or longer[1]. More concerning is the phenomenon known as long COVID, where symptoms including joint pain persist for months after the initial infection has resolved. This prolonged pain may be due to ongoing inflammation, nerve irritation, or immune system dysregulation[1][5].
Research has found that some individuals develop autoimmune markers months or even years after COVID-19 infection. Autoimmune diseases occur when the immune system mistakenly attacks the body’s own tissues, including joints. A study showed that two years after COVID-19 infection, some patients still had markers associated with autoimmune conditions such as systemic lupus erythematosus (SLE) and rheumatoid arthritis, both of which can cause joint pain and swelling[3]. This suggests that COVID-19 may trigger or exacerbate autoimmune processes in some people, leading to persistent joint symptoms.
Long COVID shares similarities with other post-infectious syndromes like myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), which also involve chronic pain and fatigue. The underlying mechanisms may include immune system dysregulation, persistent viral fragments, blood vessel dysfunction, and neurological issues affecting pain signaling[5]. These complex interactions can maintain or worsen joint pain long after the virus is gone.
In summary, joint pain after COVID-19 arises primarily from the body’s inflammatory response to the virus, direct viral effects on tissues, and in some cases, autoimmune reactions triggered by the infection. The persistence of joint pain in long COVID reflects ongoing immune activity and possibly nerve involvement, making it a multifactorial condition that can vary widely between individuals.
Sources:
[1] ER Dallas, COVID Body Aches: Causes, Relief & When to Seek Help
[3] Autoimmune Institute, Autoimmune Markers Persist Two Years After COVID-19
[5] Wikipedia, Long COVID
