Harpagosides are iridoid glycosides found primarily in the roots of Harpagophytum procumbens, commonly known as Devil's Claw. The use of Devil's Claw for musculoskeletal pain, including tendonitis, is based largely on traditional medicine practices in southern Africa, where the plant has been used for centuries to address a variety of inflammatory and pain-related conditions. In Europe, Devil's Claw extracts have been adopted as herbal remedies for back pain, osteoarthritis, and general inflammatory disorders of the musculoskeletal system, sometimes including tendonitis.

Scientific studies on harpagosides primarily focus on their anti-inflammatory and analgesic effects, particularly in osteoarthritis and low back pain. While some clinical trials report modest benefits for these conditions, there is a lack of robust, direct evidence from randomized controlled trials specifically investigating harpagosides or Devil’s Claw extracts for tendonitis. The proposed mechanism involves inhibition of inflammatory mediators such as COX-2 and TNF-α, which could theoretically benefit tendon inflammation, but this remains speculative. Systematic reviews and authoritative sources, including the European Medicines Agency, acknowledge traditional use for minor joint pain, but do not substantiate efficacy for tendonitis specifically. As such, while harpagosides are traditionally used for conditions like tendonitis, scientific validation for this specific indication is limited.