<s>[INST] Hi, my teenage son is in hospital with Leptospirosis. He had acute renal failure but is ok now. He was on Penicillin G for 21/2 days but now they have switched him to Calvepen orally. Does this work in Leptospirosis as I can't find anything on the web - this page opened! [/INST] Hello and Welcome to ‘Ask A Doctor’ service. I have reviewed your query and here is my advice. He had a severe form of leptospirosis and luckily he survived. Penicillin is the preferred drug for leptospirosis. Calvepen is the brand name of Penicillin V and which is the oral Penicillin. So his treatment is in the right track and nothing much to worry now. Hope I have answered your query. Let me know if I can assist you further. Regards, Dr. Shinas Hussain </s>