The novelist passed away aged 41, why she died remained a mystery, although Addison's disease and lymphoma were initially believed to be possible causes of death.

In December 1816, Jane told her nephew, James Austen-Leigh, that she found walking out to dinner “beyond her strength”. In March 1817, writing to her niece, Fanny Knight, she described her face as, “black and white and every wrong colour”, evidence of the butterfly rash seen in some lupus patients. By April she had become confined to bed.

In 2022 retired surgeon Michael Sanders, by reviewing all of Austen's available letters and extricating relevant medical information, put forward the conclusion that the cause of death was systemic lupus erythematosus. Her symptoms included rheumatism, facial skin lesions, fever and marked fluctuation of these symptoms. The severity of her symptoms increased, leading to her death within a year. Michael Sanders findings were published in Lupus a SAGE Journal.