i carry the herpes virus and get cold sores from
It may transmit in case of active lesion like cold sore.
I can understand your concern. It may transmit to your son by kissing on cheek, if presently you have any active lesion like cold sore. As you are on tab. Valtrex, it reduces risk of transmission of infection and lower intensity and frequency.
So during active lesions, avoid any direct physical contact with other people. Don't share any utensils, clothes, lip balm, makeup. Wash your hands properly after applying medications.
Along with that take balanced diet keep your self hydrated. Regarding your son, Watch for symptoms like fever, cold sore, weakness.
Hope I have answered your query. Let me know if I can assist you further. Thank you.
Dr Shyam Kale
Family and general physician