I have read with interest the various comments about when dad calls.
The one thing that hasn't been mentioned is patient confidentially.  Even in
the most loving of relationships there are what we would call secrets however
the law looks at it as confidentially issues.
The original question was about a dad calling for information about prozac
(Playing devil's advocate here) Now --- What if the mom was severely depressed
because of the dad, what if there was a custody battle ensuing?  What if he
was trying to prove she's too crazy to take care of the baby?  Or too crazy to
take the medication the doctor prescribed because of "this breastfeeding
thing?"
Ok now that you have that picture.
Information regarding SELF TREATMENT has to be given to the patient.  (Or in
the case of a minor: to the minor's care giver)
Let's say you are returning calls, someone other than mom answers and mom is
not home.  Do you give them the answer(s) to the mom's questions?  If you do,
you shouldn't.  There is no way to verify that the mother got the information
much less verify that she understood.
Obviously, this doesn't apply to pump rental rates and non-treatment issues.
Local laws vary, as do those for LC's who are licensed (MD,RN, PT etc..).
Even if they are primarily practicing as an LC they need to check the
"Practice Act" for their state.  There are some states where recommending OTC
products is considered practicing medicine without a license.
This is why ALL LC's need a good breastfeeding friendly MD mentor and written
treatment protocols for everything they do.
Off the soap box
Marie Davis RN, IBCLC