Absorption of fat-soluble vitamins and other fat-soluble nutrients is inhibited by the use of orlistat. A multivitamin tablet containing vitamins A, D, E, K, and beta-carotene should be taken once a day, at bedtime, when using orlistat.[18]
On June 4, 2009, the U.S. Food and Drug Administration released its quarterly list of drugs that are under investigation for potential safety issues or new safety information. Orlistat was included in the list as having a "Potential Signal of Serious Risk" of liver toxicity, meaning that a potential risk of liver toxicity was identified based on reports to the FDA Adverse Event Reporting System between October and December 2008.[28] Isolated cases of orlistat-associated liver problems have been reported before.[29] On August 24, the FDA reported that it would investigate 30 cases of liver damage reported between 1999 and October 2008 in patients taking orlistat, including six cases of liver failure.[30]