Objective To investigate the association between the Geriatric Nutritional Risk Index （GNRI） and the prognosis of patients with erythroderma， and to assess its effectiveness in predicting adverse outcomes， thus providing a basis for nutrition risk stratification and management. Methods A total of 183 hospitalized patients aged ≥ 60 years with erythroderma from the Guangdong Provincial Hospital of Chinese Medicine between August 2017 and October 2024 were recruited. Clinical data were gathered， and the GNRI was computed. The subjects were classified into a no nutritional risk group （n = 78）， a mild nutritional risk group （n = 39）， and a moderate-to-severe nutritional risk group （n = 66） according to their GNRI. A generalized linear model was employed to analyze the association between the GNRI and prognosis， and receiver operating characteristic （ROC） curves were drawn to assess the predictive performance of the GNRI for prognosis. Results The moderate-to-severe nutritional risk group exhibited a significantly elevated risk of infection （OR = 4.81， 95%CI： 1.54 - 15.99， P = 0.007）. Specifically， there was a higher risk of pulmonary infection （OR = 8.00， 95%CI： 1.01-63.28， P = 0.049）， and a significantly extended hospital stay （β = 2.53， 95%CI： 0.96 - 4.10， P = 0.002）. The area under the curve （AUC） of GNRI for predicting infection in patients with erythroderma was 0.71 （95%CI： 0.61 - 0.81）， and the AUC for predicting pulmonary infection was 0.81 （95%CI： 0.65 - 0.96）. Conclusions The GNRI serves as an effective indicator for predicting infections， especially pulmonary infections， among elderly patients suffering from erythroderma. Moderate-to-severe nutritional risk is notably correlated with elevated infection rates and extended hospital stays. Consequently， it is advisable to adopt the GNRI as a routine nutritional screening tool for elderly erythroderma patients and to carry out early interventions based on risk stratification to enhance clinical outcomes.