Hello there, Like all vaccines, Pentaxim too can have side effects. It can cause local reactions at the injection site such as pain, redness and induration may occur within 48 hours of administration. Apart from this more generalized reactions can occur like fever, irritability, drowsiness, sleeping and feeding disturbances, diarrhoea, prolonged inconsolable crying. So it is unlikely that the symptoms are due to Pentaxim vaccination. It is likely that your child has upper respiratory tract infection. Please give Nasivion P nasal drops to control the same. Bring down the fever with paracetamol drops in correct dose and frequency. Take care.