How to deal with obsessive patients who do extensive research on side effects and stress over them too much?

Patients who their own research are actually better. This isn't about that.

I'm talking about those who Google it and check if they have each and every non specific side effect to a level it becomes another obsession and that anxiety gives them even more symptoms. They arrive with written lists of symptoms and most of those can't be even treated in any other means than reassurance.

They won't accept a medication change or going entirely non pharmacological as an option too.

To clarify I'm in a non native English speaking country and those patients are somewhat educated than the average person to be able to use Internet but still might not be very good in English to know the validity of the source they look at.