Just a heads up. The morning after taking the recommended dosage of NyQuil for a persistent cough the fluid in my right eye contracted. I thought there might be retina damage so I made an appointment with the doctor. No retina damage but the fluid had indeed contracted and was causing hundreds of small floaters like tiny dots, as well as large floaters and light flashes.
I feel there may well be a link between the NyQuil and the eye damage.
In general big pharma is something to be avoided as much as possible. They make their money as long as we are sick. They make their money by treating symptoms not by curing.