The causes of rheumatoid arthritis are mainly classified into four categories,

First, environmental factors, such as living in dark, damp conditions for a long period, may trigger the onset of rheumatoid arthritis.

Second, genetic factors, the probability of developing rheumatoid arthritis significantly increases if a parent has the condition.

Third, rheumatoid arthritis often relates to estrogen, thus it is more commonly seen in female patients clinically.

Fourth, rheumatoid arthritis is also associated with certain infections, including some viral and bacterial infections.