Abstract
Background: Pain is an unpleasant sensation that can be caused by tissue damage and injury or caused by ongoing tissue damage. From a long time ago,the use of herbal medicines has been considered to treat a variety of diseases, including reducing or relieving pain. Many therapeutic effects have been attributed to various alkaloids in the barberry plant (Berberis vulgaris) and Berberine can be considered to have the most therapeutic effects. Based on the available evidence, in this study, we aimed to evaluate the analgesic effects and effectiveness of Berberine on how and what extent to improve or reduce pain. 
Methods:  In this study, in order to evaluate and recognize the analgesic effects of Berberine, the standard and well-known methods of assessing the amount and severity of pain were used: Hot plate and Tail flick devices. The experiments were performed in 11 groups with 6 male mice in each group including the experimental groups (Berberine), the positive control group (piroxicam), and the negative control group (normal saline), and all administrations were performed by intraperitoneal injection. In the Hot plate test, the delay time in lifting or licking the foot was measured and in the Tail flick test, the time it took for the mouse to pull its tail away was recorded by focusing the painful thermal stimulus on a portion of the animal’s tail. Data obtained from each group were analyzed separately by SPSS software and one-way ANOVA test.
Results:  Berberine at doses of 6, 3, and 1.5 mg/kg had significant analgesic effects compared to the control group in 30 minutes in both tests (P <0.01). Concomitant injection of 3 mg/kg of Berberine with 15 mg/kg of piroxicam produced significant analgesic effects compared with 15 mg/kg piroxicam injection alone (P <0.05).
Conclusion: The results indicate that Berberine was able to increase the delay time in response to analgesic stimuli in pharmacological tests in a dose-dependent manner. Based on the available evidence, it is suggested that concomitant use of Berberine with piroxicam can lead to synergy and improve the effectiveness and relief of pain, especially in acute and severe pain in patients. Also, concomitant use of berberine with piroxicam can reduce the therapeutic dose of piroxicam and attenuate its side effects.