Smilax regelii is a perennial, trailing vine with prickly stems that is native to Central America. Common names include sarsaparilla ( /ˌsæspəˈrɪlə/ or /ˌsɑːspəˈrɪlə/), Honduran sarsaparilla, and Jamaican sarsaparilla. It is known in Spanish as zarzaparrilla, which is derived from the words zarza, meaning "shrub", and parrilla, meaning "little grape vine".

Smilax regelii was considered by Native Americans to have medicinal properties, and was a popular European treatment for syphilis when it was introduced from the New World. From 1820 to 1910, it was registered in the U.S. Pharmacopoeia as a treatment for syphilis. Modern users claim it is effective for eczema, psoriasis, arthritis, herpes, and leprosy, along with a variety of other complaints. There is no peer-reviewed research available for these claims. There is, however, peer-reviewed research suggesting that S. regelii extracts have in vitro antioxidant properties, like many other herbs.

Smilax regelii is used as the basis for a soft drink, frequently called Sarsaparilla, or "looga". It is also a primary ingredient in old fashioned-style root beer, in conjunction with sassafras, which was more widely available prior to studies of its potential health risks. Sarsaparilla drinks feature widely in American popular culture, particularly in works related to the American West (often called, incorrectly, "sassparilla") and the pioneer period. Sarsaparilla is not readily available in most countries, although many pubs and most major supermarket chains in the Philippines, Malaysia and Australia stock sarsaparilla-flavored soft drinks.