Thanks for your question on Health Care Magic. I can understand your concern. Lung infection in 8 month of child is known to cause electrolyte disturbance. Acute lung infection causes hypokalemia, hyponatremia, hypomagnesemia etc. Diarrhoea and vomiting are common cause for electrolyte disturbance. But they are not the only cause. Pneumonia is also a common cause. So to prevent this electrolyte deficiency, pediatrician has prescribed pedialyte. So give your grandson pedialyte, it is beneficial in lung infection. Hope I have solved your query. I will be happy to help you further. Wishing good health to your grandson. Thanks.