Ben, on the serious side, it appears Zicam is not harmless:
https://sciencebasedmedicine.org/fda-zicam-warning/
The FDA issued a warning in 2009 and there also have been a number of successful lawsuits against the manufacturer for side effects of the drug. I am not surprised about one of them, anosmia. I am a neuroscientist and the effects of zinc on the olfactory system, at very small amounts, have been known for a while: it blocks the sense of smell by binding to membrane surface receptors of sensory cells in the olfactory bulb. A couple of decades ago, deodorant manufactures began adding zinc to deodorants, as a way of blocking the sense of smell on people around you while they are around you. Only it blocks all smells, not just your bodily smells.
At the amounts you get in Zicam, it can lead to total loss of smell. Not everyone suffers the side effects, and they have a different time of onset. So, you are playing russian roulette.
Do a google search for "Zicam side effects." Look for it in NIH sites or the FDA if you want reliable information.
As for its efficacy in cold prevention, the onset, severity of symptoms and time course of colds is so variable depending on the strain you are exposed to, the state of your health at the time of exposure, etc, that you can't really go by personal experience. It is only through clinical studies, when the effects of a drug are monitored under controlled standard conditions, comparing experimental and control groups that you can reach reliable conclusions.
Feb 17, 18 13:28