Systemic disease

This article's lead section may be too short to adequately summarize the key points. Please consider expanding the lead to provide an accessible overview of all important aspects of the article. (April 2018)

A systemic disease is one that affects a number of organs and tissues, or affects the body as a whole.^[1] It differs from a localized disease, which is a disease affecting only part of the body (e.g., a mouth ulcer).