Studies have shown that arthritis (joint inflammation) and arthralgias (joint pain) are reported in up to 95 percent of patients with systemic lupus erythematosus (SLE).
There is currently no evidence for the use of collagen supplements in lupus patients. Actually, some decades ago, these supplements have been suggested in patients with osteoarthritis. The reason for this, is that the pathology of OA results from focal and progressive hyaline articular cartilage loss which leads to changes in the bone underneath the cartilage. However, while the prescription of collagen supplements was very trendy some decades ago, their use has slowly declined due to growing evidence failing to show an efficacy of these collagen supplements. Here the conclusion of a systematic review conducted in 2013 on this topic:
There is insufficient evidence to recommend the generalized use of CHs
in daily practice for the treatment of patients with OA. More
independent high-quality studies are needed to confirm the therapeutic
effects of collagen derivatives on OA complaints.
Of course this concerns osteoarthritis but it shows of controversial collagen supplements are.
As summarised in uptodate, treatment of arthritis in lupus patients relies on the following drugs: nonsteroidal antiinflammatory drugs or hydroxychloroquine. For some patients acetaminophen may be useful. Glucocorticoids, methotrexate, and other immunosuppressives may also be required.
Schur P. et al. Musculoskeletal manifestations of systemic lupus erythematosus. Aug 30, 2016. http://www.uptodate.com/contents/musculoskeletal-manifestations-of-systemic-lupus-erythematosus?source=machineLearning&search=lupus+arthritis&selectedTitle=1%7E150§ionRank=1&anchor=H2#H499515