•  DOI: 10.1002/ptr.5377
• Published online 22 May 2015 in Wiley Online Library

Mohd Shara1 and Sidney J. Stohs2

• 1 Faculty of Pharmacy, Jordan University of Science and Technology, Irbid 22110, Jordan
  2 School of Pharmacy and Health Professions, Creighton University Medical Center, Omaha, NE 68168, USA

Abstract

Willow bark extract has been used for thousands of years as an anti-inflammatory, antipyretic, and analgesic. In spite of its long history of use, relatively few human and animal studies have been published that confirm anecdotal observations. A small number of clinical studies have been conducted that support the use of willow bark extracts in chronic lower back and joint pain and osteoarthritis. Willow bark extracts also are widely used in sports performance and weight loss products presumably because of anti-inflammatory and analgesic activities, although no human studies have been published that specifically and directly document beneficial effects. In recent years, various in vitro and animal studies have demonstrated that the anti-inflammatory activity of willow bark extract is associated with down regulation of the inflammatory mediators tumor necrosis factor-α and nuclear factor-kappa B. Although willow bark extracts are generally standardized to salicin, other ingredients in the extracts including other salicylates as well as polyphenols, and flavonoids may also play prominent roles in the therapeutic actions. Adverse effects appear to be minimal as compared to non-steroidal anti-inflammatory drugs including aspirin.

INTRODUCTION
White willow bark extract is an extract of the white bark of Salix alba that is standardized for its salicin content. Various grades of the extract are commercially available and contain, for example, 15%, 25%, or 50% salicin. Historically, willow bark has been used for over 2000 years,
initially in the Mediterranean region including Egypt and Greece and subsequently in China, Europe, North America, South America, and Caribbean. Use of willow bark extract to treat pain and fever was reported in 1763 in England (Highfield and Kemper, 1999).
White willow bark extract is widely used for conditions associated with pain, inflammation, or fever such as joint or knee pain, acute back pain, osteoarthritis, headache, menstrual cramps, tendonitis, flu symptoms including fever, and generalized pain (Highfield and Kemper, 1999). A limited number of clinical studies have been conducted with willow bark extract, and
these as well as animal and mechanistic in vitro studies will be summarized in the succeeding sections.

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Reference:

https://onlinelibrary.wiley.com/doi/10.1002/ptr.5377