First, your friendly nurse should have recommended he see a psychiatrist to discuss any medication changes. These two drugs won't have adverse interactions, benzos are not only often but usually used with antidepressants. However, the dose will depend on the individual, and so will the drug. Prozac is one of the easier drugs to stop taking -- the one he's taking and the way he's taking it will make it possibly very hard to stop taking. When an antidepressant works, it works all the time, not just temporarily as benzos do, but Prozac is a more stimulating antidepressant and so is often not effective with anxiety. However, it's always worth a try because it stays in the body longer than other drugs in its class and is thought therefore to be much easier to stop taking.