C.J.
In addition to following her doctor's advice, get a netti pot. Sinuses are affected by pregnancy as well as mucus production. It makes you more prone to being "stuffy" and infection. Using a netti pot both morning and evenings is a great way to proactively address the situation drug free. It saved my life with my pregnancies and I still use it now when my allergies flair up.
I also am going to pass on some advice I read on this forum - just because she can take it, she still needs to watch dosage and frequency. It could still be harmful to baby even though "approved" or considered "safe." If she is taking more than recommended daily dosage or taking both at the same time, etc.
A good sit down with Dr would be a great start!