Among a unicorn's magical powers is the ability to eliminate and antidote all poisons. Allegedly dipping the unicorn's horn, the alicorn, into any food or liquid automatically removes any trace of poison. That legend has wreaked devastation on narwhals and rhinoceroses over the centuries, at a time when few were aware of fauna outside their immediate area, it was easy to pass off another species' horn as an alicorn. Of course, they didn't work as intended, but then, of course, they weren't real unicorn horns. Unicorns allegedly shed their alicorns annually like deer antlers.
If the unicorn doesn't actually shed its alicorn (horn) directly into your hand, it's a safe bet a horn is not genuine alicorn. However, that doesn't mean you cannot tap into the power of the alicorn, or unicorn's horn.
If you have reason to be fearful of poisoning or other physical harm, burn a white, black or red unicorn shaped candle. As the candle is burning, transmit your petition of protection to presiding unicorn spirits. You can also consecrate a unicorn charm or talisman by passing it through the flame and then laying it beside the candle while it burns.
Once consecrated, wear it for protection. Should the charm suddenly call attention to itself, it is sounding a warning. Pay attention and take action as needed. Whenever you feel the charm has worked its magick to protect you, cleanse and reconsecrate it, offering thanks to the unicorn spirits.
From: The Element Encyclopedia of 5000 Spells