Giving ur baby drugs before immunization will make the drug not to be effective. Even giving ur baby drugs immediately immunization can also cause the drugs not to be effective so what u will do is to be checking ur baby once you notice he is running a small temperature u can give him drug.
When my baby took his six weeks immunization nothing do him so no need of giving him drug. He took his 10 week's I don't give him drug immediately but later I notice that he is running a small temperature I then give him drug. He took his 14 weeks nothing happen so no need of giving him drug.