Thanks for the reply.
Yes, a netipot can cause pnd for a few hours after using it. It is designed to wash out the nasal passages and to loosen the mucus that gets really thick. When the mucus is loosened it will start to drain. Depending on how severe your symptoms this drainage can last a couple of hours.
That is what my experience has been. I have chronic sinus infections which antibiotics do not adequately clear up. I've taken to using a netipot frequently and my drainage is actually decreasing.