Introduction: Primary dysmenorrhea (PD) is a highly prevalent gynecological condition among adolescents and women of reproductive age, often inadequately managed by conventional analgesics due to side effects or contraindications. Purpose: This review evaluates the efficacy, mechanisms, and safety of Foeniculum vulgare (fennel) as a phytotherapeutic alternative for PD. Methods: This article is a narrative review that synthesizes the available evidence on the efficacy and safety of Foeniculum vulgare in primary dysmenorrhea. Owing to the heterogeneity of the available studies and the limited standardization of interventions and outcomes, a quantitative meta-analysis was not performed and reviews continued through to September 2025. Databases included PubMed, Scopus, and Google Scholar. Inclusion criteria were human studies on fennel for PD, reporting pain outcomes, safety, or biological mechanisms. Results: Twelve randomized or quasi-experimental trials (n> 800) demonstrated that standardized fennel extract (30 mg three times daily, initiated premenstrually) significantly reduces pain intensity, duration, and systemic symptoms (nausea, fatigue) over 1– 3 cycles, with efficacy comparable to ibuprofen or mefenamic acid. Mechanistically, fennel inhibits prostaglandin synthesis via COX-2 suppression, blocks voltage-dependent calcium channels, and exerts antioxidant and mild phytoestrogenic effects. Adverse events were rare and mild (transient dizziness), with no serious toxicity reported in adolescents or adults. Conclusion: Fennel is a safe, effective, and culturally acceptable herbal intervention for primary dysmenorrhea. Its integration into clinical practice offers a viable alternative for NSAID-intolerant or hormone-averse individuals. Future research should prioritize standardized, multicenter trials with objective biomarkers to establish definitive dosing guidelines. Plain Language Summary: Why this study was conducted Many young women suffer from painful periods (primary dysmenorrhea), but common painkillers can cause stomach problems or are not suitable for everyone. There is growing interest in safe, natural alternatives like fennel, which has been used traditionally for menstrual pain. What the researchers did and found We reviewed all high-quality studies on fennel for period pain. We found that taking fennel (usually as 30 mg capsules three times a day, starting a few days before the period) reduces pain and related symptoms like nausea, as effectively as ibuprofen—but with fewer side effects. Lab studies show fennel works by calming uterine contractions and reducing inflammation. Implications of these results Fennel can be a reliable, low-risk option for managing menstrual pain, especially for teenagers and women who cannot take NSAIDs. Healthcare providers, including nurses and midwives, can recommend it as part of comprehensive menstrual care based on individual conditions and expert opinion. The infographic presents conclusions about fennel. It highlights that fennel reduces dysmenorrhea, with mechanisms including anti-inflammatory and antioxidant activity. It also notes that fennel alleviates symptoms in multiple clinical trials. An illustration of fennel is shown with arrows pointing to text and an arrow indicating its effect on inflammation and pain.Infographic illustrating that reduces dysmenorrhea through Ani inflammatory an antioxidant activities,as supported by clinical trail evidence. Keywords: primary dysmenorrhea, Foeniculum vulgare , phytotherapy, pain management, herbal medicine, fennel
Kakhki et al. (Fri,) studied this question.