For?
I have taken to using diphenhydramine and vitamin c megadoses when I get illness symptoms (flu-like) The idea is to suppress the histamine response which is part of the problem with viruses.
Most "bad viruses" end up triggering the MAPK signalling cascade in infected tissues and the body's swelling response is what causes the majority of the damage. Your body literally self-destructs by over-encoding for a hydrolyzing enzyme that dissolves the cell membrane.
Diphenhydramine is inferior to some of the MAPK inhibitors being trialed, but is available over the counter and has been shown to reduce swelling from many viral infections.
Vitamin C is a precursor to most stress response and repair hormones, the megadosing is to cut out the body's need to recycle vitamin c. We are very good at recycling vitamin c, but our gene for the protein that makes vitamin c out of glucose is mutated and dysfunctional.
When the medical infrastructure turns from a profiteering scheme to a curative ambition, it will be some real Tree of Life and healing rivers stuff.