I was prescribed it when I was prescribed Diclofenac, to take beforehand to avoid stomach problems. However, our GPs have decided to try to get patients off Diclofenac and I try to do without them. The young GP I saw told me to keep the Omeprazole I had already and use them if I felt I needed them. He said that he and his young family all took them if they were going on a journey and if they are away in a foreign country.
However, I have read about many side effects and decided not to take them unless absolutely necessary. These side effects will not apply to everyone, and I do not want to take them because I am on other medication.
Perhaps it would be best for your DD to see her GP to ask about DGS's possible side effects.
I have had vertigo due to an ear problem, but it caused nausea and a spinning sensation rather than seeing things.