The severity of interstitial nephritis is closely related to the urgency of the onset of the disease, the etiology and the renal function status of the patient, and cannot be generalized. Interstitial nephritis is a group of clinicopathologic syndromes caused by a variety of etiologic factors, and its main clinical manifestations are renal tubular dysfunction, accompanied by varying degrees of decline in glomerular filtration rate; pathological damage mainly involves the renal interstitium and renal tubules, with no or only minor glomerular or tubular damage. The causes of interstitial nephritis include drugs (analgesics, aristolochic acid), followed by autoimmune diseases (dry syndrome, systemic lupus erythematosus), infections, tumors, and metabolic disorders, etc. The severity of interstitial nephritis varies with different causes, and needs to be considered comprehensively. According to the rapidity and slowness of the onset of the disease and the different pathological changes, it is divided into acute tubulointerstitial nephritis and chronic tubulointerstitial nephritis. The former has an acute onset and progresses rapidly, and may become chronic if the cause is not removed and effectively treated; the latter has an insidious onset and progresses slowly, and some patients may have repeated exacerbations of acute inflammatory lesions due to different causative factors. The severity of renal interstitial inflammation requires individualized analysis, and it is recommended that patients go to the hospital, under the guidance of specialists to clarify the condition and standardize the diagnosis and treatment, so as not to delay the condition.