The DPT or Penta injection is usually given deep into the muscles. One of the side effects is swollen/red injection site due to some mild bleeding into the muscle. It needs to be properly managed so it does not become infected and turn into an abscess. If the site become bigger and soft with pus inside - that is an abscess, pls go back to the Hospital or Health Centre do it can be drained and additional treatment including antibiotics will be given