False friends are quite common between Spanish and English. These two languages often have words derived from a common etymological stem (usually Latin) but that eventually have evolved to different meanings. Some common examples are "carpet" and "carpeta" (folder) or "to remove" and "remover" (to stir). Even Babelfish translates the latter wrongly!

Confusion is usually harmless, but not always: if you natively speak Spanish and catch a cold while abroad, you might find yourself in trouble if you ask the pharmacist for some drug to cure a constipation.