Lime, or calcium oxide, is poisonous when swallowed, according to Medline Plus. Calcium hydroxide is a poisonous combination of calcium oxide (lime) and water. It is normally found in cement, limewater, and industrial solvents and cleaners. Calcium oxide itself is poisonous, according to the Espi Metals website.
Medline Plus states that symptoms of calcium hydroxide poisoning include loss of vision and severe pain in the throat, nose, eyes, ears, lips or tongue. Victims of calcium hydroxide poisoning can also experience severe abdominal pain and may vomit blood. If symptoms of calcium hydroxide poisoning are observed, one should immediately seek medical help. If the chemical is on a person's skin or in their eyes, flushing with large amounts of water for a minimum of 15 minutes is recommended.