Still’s disease in adults is a clinical syndrome of unknown etiology with a prolonged intermittent, transient polymorphic rash, arthritis or arthralgia, and systemic involvement such as elevated peripheral blood count and granulocytes and impaired liver function. It is called “allergic subsepsis” because of its clinical resemblance to sepsis or infection-induced metaplasia. Since 1995, 500 cases have been reported in the literature, with more unreported cases, so it is a relatively common disease. These two names have long been abolished internationally and domestically, and are uniformly referred to as adult Still disease, or more precisely, adult-onset Still disease (AOSD). It is thought to be an allergic disease between rheumatic fever and juvenile forms, and is very similar to the acute systemic form of juvenile rheumatoid arthritis (Still’s disease). It is also thought to be a clinical stage of rheumatoid arthritis or one of its clinical variants. However, most patients have been observed over time without sequelae such as joint ankylosis or deformity. Adult Still disease is a rare type of rheumatoid arthritis with a clinical presentation similar to that of juvenile rheumatoid arthritis with a generalized onset. It is characterized by sore throat, sudden high fever of unknown origin, reaching 39-40°C or more. The fever may last for weeks or months and is accompanied by a rash on the trunk and extremities, which is not itchy and disappears when the fever subsides. Joint symptoms are not prominent at the beginning, and usually only a few joints are involved, mostly large joints such as knees, ankles, wrists, etc. Some patients only have pain without swelling, which can be reduced as the fever subsides. Most patients develop classic rheumatoid arthritis after several weeks, months or even years of fever. This type of patient has alternating cycles of attacks and remissions. High fever, rash, arthralgia and elevated white blood cells, three out of four, and exclusion of other causes of fever such as infections and tumors are required to diagnose adult siderosis. It was previously named subseptic and allergic subseptic disease. The disease is most often seen in young adults, 18-25 years of age, with an approximately equal incidence in men and women. Adult Still’s disease is treated with the following: (1) Glucocorticoids: Prednisone 1mg/(kg-d), after symptoms improve, gradually reduce the dose, the total course of treatment should not exceed 6 months. The total course of treatment should not exceed 6 months. Non-steroidal drugs can be added during the process of dose reduction to consolidate the therapeutic effect. When the efficacy is not good, high-dose methylprednisolone shock treatment can be used. (2) Non-steroidal anti-inflammatory drugs: NSAIDs can be used alone in mild cases, such as naproxen 0.2g twice daily, indomethacin 25mg three times daily, and fotarolimus 25-60mg three times daily. (3) Slow-acting antirheumatic drugs: if the disease is not well controlled for a long time and glucocorticoids are not effective, the following drugs can be used. Methotrexate, Ryder, penicillamine, salazosulfapyridine and rheumatoid polysaccharide, etc. The dosage is shown in the treatment of rheumatoid arthritis. Most patients have a good prognosis. 1/5 patients have remission within 1 year and no further relapses. 1/3 patients have complete remission after several recurrent episodes, with a variable time to relapse, but the symptoms are often milder and shorter in relapse than in the first episode. The rest of the patients have a chronic course, mainly chronic arthritis, and a few may progress to severe joint destruction, which may lead to joint ankylosis and even joint replacement. Polyarthritis (≥4 joints involved) or involvement of the foot, shoulder and hip joints tend to become chronic.