The Peanut Butter Solution (1985) on Netflix

This is the story about an average 11-year old boy named Michael Baskin. His father, Billy Baskin, is a struggling artist and temporary sole caregiver of the children while his wife attends to the needs of her recently deceased father in Australia. Upon hearing the news Michael does not know this yet, but his fearsome run in with the ghosts has given him a mysterious illness simply known as "The Fright". Michael wakes up the next morning to find out that "The Fright" has made him lose all of his hair. Peanut butter is the secret ingredient recipe for a magic potions made by two friendly ghosts. The ghosts also give Michael special instruction not to add too much peanut butter, as it will end in dreadful results.