To assess the effects of medicinal plants (MPs) or related natural products (RNPs) on fibromyalgia (FM) patients, we evaluate the possible benefits and advantages of MP or RNP for the treatment of FM based on eight randomized placebo-controlled trials (RCTs) involving 475 patients. The methodological quality of all studies included was determined according to JADAD and “Risk of Bias” with the criteria in the Cochrane Handbook for Systematic Reviews of Interventions 5.1.0. Evidence suggests significant benefits of MP or RNP in sleep disruption, pain, depression, joint stiffness, anxiety, physical function, and quality of life. Our results demonstrated that MP or RNP had significant effects on improving the symptoms of FM compared to conventional drug or placebo; longer tests are required to determine the duration of the treatment and characterize the long-term safety of using MP, thus suggesting effective alternative therapies in the treatment of pain with minimized side effects.