My Son Is 2.5month Old. He Have Cold And Plegm

My son is 2.5month old. he have cold and plegm gets blocked around his nose and chest but does not have a running nose and he finds it difficult often to breathe and have frequent vomitting sensation but nothing goes out. Doctor prescribed 1ml deriphyllin 3 times a day. Is that safe. Can deriphyllin be used to treat such problem