Because of the unicom's purity, its horn, sometimes called an 'Alicorn', was considered magical and became a popular ingredient in medieval medicines. Its mere presence was considered a strong protection against poison in food, and when worn in jewelry, it protected the wearer from evil.

Alicorn was often worth more than its weight in gold, so kings, emperors, and popes were among the few people able to pay the high prices demanded. They were eager to acquire the precious horn to "guarantee" long and healthy lives. With such a lucrative trade, false alicorn was rampant, made from bull horn, goat horn, or in some cases from the horns of exotic animals or from ordinary dog bones.

Complete Unicom horns were very rare. For example, a complete Unicom horn owned by Queen Elizabeth I of England was valued at the time at £10,000 - the equivalent of about 3,000 ounces of gold and enough money to buy a large country estate complete with a castle. Rather than coming from unicorns, these complete horns often turned out to be the long spirally twisted tusks of the male narwhal, a large marine animal. Kings often placed alicorn on the table to protect themselves against poisonous food and drink, and until the revolution toppled the monarchy in 1789, the eating utensils used by French kings were made of Unicom horn to counteract any poison in the food.