Introduction and Objective: Pain, a complex experience that affects health and quality of life, is commonly treated with analgesic drugs such as NSAIDs and opioids. These drugs have significant side effects. Natural plant extracts, such as fennel (Foeniculum vulgare), which possess analgesic and anti-inflammatory properties, have been considered as alternatives or supplements. This study investigated the effect of the hydroethanolic extract of fennel seeds on acute and chronic pain induced in male laboratory rats.
Materials and Methods: In this experimental-laboratory study, 24 male NMRI rats weighing 25-30 g were divided into four groups: a control group, a morphine group (morphine injection at a dose of 10 mg/body weight subcutaneously 30 minutes before the test), a group receiving hydroethanolic extract of fennel at a dose of 500 mg/liter of drinking water for 30 days, and a combined extract and morphine group. The extract was prepared by immersing ground seeds in 70% ethanol. The analgesic effect was evaluated using the formalin test. Data were analyzed using one-way analysis of variance and the Tukey test.
Results: The extract, with or without morphine, resulted in a significant reduction in pain score in the peripheral phase compared to the control (P<0.001). A significant reduction was also observed in the acute phase in both the extract and combined groups (P<0.05, P<0.001). In the chronic phase, pain reduction was significant (P<0.001), but less than that of morphine and not significant (P>0.05). The combined extract and morphine group showed the greatest reduction in pain score (P<0.001).
Conclusion: The hydroethanolic extract of fennel, as a natural supplement, can be an effective option in the management of acute and chronic pain and can enhance the analgesic effects of morphine. Further studies are necessary to identify the mechanisms and determine the optimal dose.