Medicinal liquid paraffin, also known as paraffinum liquidum, is a very highly refined mineral oil used in cosmetics and for medical purposes. This is a UK definition (British Pharmacopoeia) and the term may have different uses in other countries. The cosmetic or medicinal liquid paraffin should not be confused with the paraffin (or kerosene) used as a fuel.
The term paraffinum perliquidum is sometimes used to denote light liquid paraffin. Conversely, the term paraffinum subliquidum is sometimes used to denote a thicker (more viscus/oily) mineral oil.
Liquid paraffin is considered to have a limited usefulness as an occasional laxative, but is unsuitable for regular use as it can seep from the anus and cause irritation; it can interfere with the absorption of fat-soluble vitamins; it can be absorbed into the intestinal wall and may cause foreign-body granulamatous reactions; and if it enters the lungs it can cause lipoid pneumonia.