Prolotherapy (sclerotherapy in medical literature, first article published in 1937) is a method of injectable treatment that raises the level of growth factors or the effectiveness to repair tissue repair or growth, in case of musculoskeletal conditions, pain or injuries, such as tendinopathies, sprains, neck and back pain, shoulder, knee and other joint pain.

Prolotherapy works by causing a temporary, low grade inflammation at the injection site. Secondarily growth factors are elevated and fibroblasts are activated, thus initiating a new connective tissue repair sequence, which had prematurely aborted or never started, resulting in new cell growth and collagen deposition. Biopsy studies show ligament thickening, enlargement of the tendinosseous junction, and strengthening of the tendon or ligament.

Growth factors are powerful, hormone-like proteins produced by peripheral cells. Examples include insulin-like growth factor (IGF), platelet- derived growth factor (PDGF), epidermal growth factor (EGF), fibroblast growth factor (FGF), transforming growth factor (TGF), bone morphogenetic proteins (BMPs), nerve growth factor (NGF), and hepatocyte growth factor (HGF). Normal cells require growth factors (mitogens) for proliferation; in their absence they withdraw from the cell cycle and stop developing.
 

Prolotherapy is used for musculoskeletal pain or injury which is either unresolved after eight weeks, or (if earlier) where enhanced healing is desired. Because Prolotherapy works to repair weak and painful joint areas, it is a long-term solution, with no side-effects, rather than a temporary measure such as cortisone or NSAIDS drugs, with numerous and well-known side-effects. Also, it has been found by several researchers that human and animal cells exposed to hypertonic solutions, result in a rise of growth factors.