Harpagophytum products are a treatment option for osteoarthritic and low back pain. The aim of this study was to review the safety of treatment with Harpagophytum procumbens. The databases OVID(MEDLINE), PUBMED and COCHRANE COLLABORATION LIBRARY were searched back to 1985 for studies with Harpagophytum procumbens. Twenty-eight clinical trials were identified of which 20 stated adverse events. In none of the double-blind studies was the incidence of adverse events during treatment with Harpagophytum procumbens higher than during placebo treatment. Minor adverse events occurred in around 3% of the patients, mainly gastrointestinal adverse events. A few reports of acute toxicity were found but there were no reports on chronic toxicity. Since the dosage used in most of the studies is at the lower limit and since long-term treatment with Harpagophytum products is advisable, more safety data are urgently needed.