Having a cold sore while having a 4-month-old baby can pose a risk, as cold sores are caused by the herpes simplex virus. It is important to be cautious, especially during childbirth, as newborns are vulnerable to a condition called neonatal herpes, which can be serious due to their immature immune system. This infection can be transmitted from a mother with genital herpes to her child during birth. While complications from oral herpes in infants are rare, it is still important to take preventive measures to avoid direct or indirect contact that could spread the virus. It is recommended to wash hands thoroughly, avoid kissing or sharing items that may have come into contact with the cold sore, to reduce the risk of transmission.