Essential oil

I bought runny nose and cough essential oil for bath time for my one month old but then noticed it’s recommended for 3+ months. I thought it would still be okay for any age so I didn’t think to look at what age group its recommended for. I have no clue what else to use for him. I did buy a humidifier but I’m thinking of just using a little bit of the oil as well. Good idea or no? I don’t see how oil will hurt ?