The goal of this study is to learn whether Gou-Teng-San (GTS), a traditional herbal medicine, is effective and safe for adults with episodic migraine. In this double-blind randomized controlled trial, participants with episodic migraine will be assigned by chance to a study treatment group. The study will evaluate whether GTS can reduce migraine frequency, improve migraine-related symptoms, and lessen the impact of migraine on daily life. Researchers will also monitor safety and tolerability throughout the study.

Inclusion Criteria:

• Adults aged 18 to 70 years.
• History of episodic migraine for at least 12 months before screening, meeting the International Classification of Headache Disorders, 3rd edition (ICHD-3) criteria, or clinically diagnosed migraine with no more appropriate ICHD-3 diagnosis.
• During the 28-day screening period, participants must meet criteria for episodic migraine, defined as headache occurring on >=6 and <=14 days, of which >=4 days meet at least 1 of the following: (1) ICHD-3 criteria C and D for 1.1 migraine without aura; (2) ICHD-3 criteria B and C for 1.2 migraine with aura; (3) probable migraine (missing 1 migraine criterion); or (4) headache considered to be migraine based on a positive response to migraine-specific acute treatment (e.g., a triptan or an ergotamine derivative).
• Not receiving preventive migraine medication for at least 5 half-lives before enrollment, or receiving no more than 1 preventive migraine medication at a stable dose and regimen for at least 2 months before informed consent, whether for migraine or another medical condition (e.g., propranolol for hypertension).
• Body mass index (BMI) between 17.5 and 37.5 kg/m2, and body weight between 35 and 120 kg.
• Adequate compliance with headache diary completion during screening, defined as completion on at least 24 of 28 days (>=85%), with diary data considered acceptable by the investigator.
• Able to comply with study restrictions and complete all protocol-required study procedures.
• Able to understand and sign the informed consent form.
• No major cardiovascular, hepatic, or renal disease.

Exclusion Criteria:

• Known allergy or hypersensitivity to Gou-Teng-San or any of its ingredients.
• Receipt of botulinum toxin type A injections in the head, face, or neck for any reason within 4 months before screening.
• Use of opioid-containing or barbiturate-containing medications on more than 4 days per month.
• Lack of efficacy after at least 3 months of treatment at accepted migraine treatment doses in 2 or more of the following preventive medication classes: (1) topiramate or valproic acid; (2) flunarizine; (3) amitriptyline, venlafaxine, or duloxetine; (4) atenolol or propranolol.
• Use of migraine treatment interventions within 2 months before screening, such as nerve block or transcranial magnetic stimulation.
• Clinically significant hematologic, cardiac, renal, endocrine, pulmonary, gastrointestinal, urinary, neurologic, hepatic, ophthalmologic, psychiatric, or other disease that, in the investigator's judgment, would interfere with study participation or study procedures.
• Participation in another clinical trial of a drug or medical device within 2 months before screening, or within 5 half-lives of the investigational product used in that trial, whichever is longer.
• Use of other Chinese herbal medicines within 4 weeks before screening.
• Previous exposure to monoclonal antibodies targeting the calcitonin gene-related peptide (CGRP) pathway or CGRP receptor antagonists.
• History of alcohol or drug abuse within the past 2 years.
• Women who are breastfeeding, have a positive pregnancy test at screening, or are unwilling to use contraception during the study if of childbearing potential.
• Any other condition or circumstance that, in the investigator's judgment, would make the participant unsuitable for the study or unlikely to complete the study successfully.

At this time, there is no plan to share individual participant data (IPD) with other researchers because data-sharing procedures and governance mechanisms have not yet been established. Any future data sharing will be considered only after appropriate de-identification procedures, institutional review board approval, institutional policies, and applicable regulations are in place.