Twelve RCTs (n=1,105) were included in the review.
Out of a possible 13 points, two studies scored 6, two scored 7, two scored 8, one scored 9, one scored 11, two scored 12 and two scored 13.
Osteoarthritis (5 RCTs, n=385).
Powdered Harpagophytum crude plant material performed better than placebo in patients with a wide range of osteoarthritic sites (1 study), and diclofenac and acetaminophen-caffeine use was reduced when compared with diacerhein, although there was no difference in spontaneous pain (1 study). There were greater improvements in pain and a reduction in ibuprofen usage with ethanolic Harpagophytum compared with placebo (2 studies). An aqueous extract of Harpagophytum performed better than phenylbutazone in patients with acute exacerbations of rheumatic joint and muscle pain and gouty arthritis (1 study).
NSLBP (4 RCTs, n=505).
An aqueous extract of Harpagophytum performed better than Doloteffin (2 studies), Vioxx (1 study) and placebo (2 studies) in patients with pseudo-radiating or non-radiating NSLBP. One study reported no significant difference in patients with non-radiating NSLBP when treated with an aqueous extract of Harpagophytum, compared with conventional treatments (non-steroidal anti-inflammatory drugs, exercise, massage, nerve blocks and acupuncture).
Mixed pain conditions (3 RCTs, n=215).
Dried mother tincture (1 study), aqueous extract (1 study) and ethanolic Harpagophytum (1 study) performed better than placebo.
The types and number of adverse events reported in each study were given in the review.