Introduction: Smyrnium cordifolium is used in traditional medicine to treat anxiety, pain, insomnia and complications of drug addiction syndrome, which is one of the concerns of every community. The use of opioid drugs repeatedly causes physical dependence and tolerance. Dependence can be assessed by the symptoms of sudden withdrawal of the drug by administering a drug antagonist or both. The purpose of this study was to investigate the inhibitory effects of hydroalcoholic extract of this plant on the disorders caused by the addiction withdrawal syndrome in comparison with clonidine.
 
Materials & Methods: In this experimental study, 48 mice (25-30 gr) were used and divided into 6 groups of 8 and were addicted during seven days. Saline group: this group was nonmorphine-dependent and received normal saline with the equivalent dosage. Groups 2, 3 and 4 treated with S. cordifolium hydroalcoholic extract (SCE): these groups received morphine and SCE (100,200,300 mg/kg) as gavage. Group 5 (clonidine): This group of mice received morphine and clonidine (0.2 mg/kg). Group 6 (control): this group of mice received just morphine. In all the groups, signs of withdrawal syndrome were recorded on the seventh day 30 minute after naloxone injection. The results were analyzed by one-way ANOVA and Tukey’s test at a significant level of P <0.05.
Findings: The results of this study showed that the effect of extract on the number of jumping in the SCE100 compared to the clonidine group decreased significantly (P<0.05) and SCE200 decreased significantly (P<0.01). In the SCE300 group, there was a significant decrease in this regard (P<0.001) compared to the clonidine group. Also, the effect of SCE on the maen number of rearing was ineffective in the SCE100 group, and SCE200 decreased significantly (P<0.05). In the SCE300 group, there was a significant decrease in this respect (P<0.01) compared to the clonidine group. The effect of extract on the number of teeth chatering in the SCE100 group decreased significantly compared to the clonidine group (P<0.05) and SCE200 decreased significantly (P<0.01). In the SCE300 group, there was a significant decrease in this level (P<0.001) compared to the clonidine group.
 
Discussion & Conclusions: Regarding the results of this study, SCE was capable of reducing the signs of opiate withdrawal in morphine-dependent mice. It is likely to modify the symptoms of the syndrome by activating opioid, gabanergic and serotonergic pathways. However, further studies are needed to determine the exact mechanism of the effect of SCE.