treating
v.v. to give medical care to someone or to behave toward a person in a specific way. It can also mean paying for someone else's meal or entertainment as a gift.
v. to provide medical care to a patient or to behave toward a person or thing in a specified manner. In a social context, it refers to providing someone with food, drink, or entertainment at one's own expense.
The doctor is treating her for a bad cough.
He is treating his sister to dinner at a fancy restaurant for her birthday.
While the hospital is treating the physical symptoms of the disease, social workers are addressing the psychological impact on the patient's family.
The verb is transitive and requires a direct object; when used for social invitations, it often takes the preposition 'to'.
The doctor treated to him.The doctor treated him.When providing medical care, the verb is transitive and does not take a preposition before the object.