Catechism of the Catholic Church §1529 — excerpt
Each time a Christian falls seriously ill, he may receive the Anointing of the Sick, and also when, after he has received it, the illness worsens.
This translation is under copyright, so only the cited words are quoted here. Follow the link for the full text. Translation: English translation of the Catechism of the Catholic Church, 2nd ed. (Libreria Editrice Vaticana), as posted at vatican.va.