Enovid trip report -- when I was using it 4-5 days/week for prophylaxis in a classroom setting, it seemed to exacerbate some B12 deficiency symptoms I was independently having. (NO/N2O can affect B12 uptake.) Suspect is fine for most people, but something to watch if one is using it regularly.

Some studies demonstrated similar prophylaxis effects from iota-carageenan nasal spray; I have not gotten any to use as an Enovid substitute but am thinking about it.