20 month old taking levomepromazine for about a year

Patient: Is it safe to give a 20 month old Levomepromazine? My friend has been giving this medication to her son for about a year, every night, to help him sleep. She took the baby to a neurologist a year ago because he had trouble falling asleep and also woke up multiple times during the night and he prescribed that. I recently found out that she still gives him the medication. She said the doctor told her to give it to him for a whole year and then come back to be re-evaluated. I’m concerned that it might harm him. Should I say anything to her or is it safe to do as the doctor advised her?

Symptoms: 20 month old has trouble falling asleep and staying asleep (since he was a 4 months old or so) and has been taking levomepromazine for about a year for it. I’m concerned the medication might harm him and wondering if the doctor’s advice should be trusted.