Chinese Herbal Sachet Inhalation for Primary Dysmenorrhea in Female College Students

Design: single-centre, randomized, single-blind (participant), placebo-controlled, two-arm parallel-group trial.

Randomization: participants were numbered in order of recruitment and allocated 1:1 using a computer-generated random number table (SPSS).

Intervention: herbal sachet containing Angelica dahurica root 5 g, Syzygium aromaticum flower bud 5 g, Artemisia argyi leaf 5 g, Foeniculum vulgare fruit 5 g, Kaempferia galanga rhizome 5 g, Cinnamomum cassia bark 10 g, Angelica sinensis root 10 g, Ligusticum chuanxiong rhizome 10 g, Cyperus rotundus rhizome 10 g, Aucklandia lappa root 10 g, Rosa rugosa flower bud 15 g, Osmanthus fragrans flower 15 g and Liquidambar orientalis resin 0.1 g, ground to powder and sealed in a non-woven bag inside a mesh pouch. The formula was developed through a three-round Delphi expert consensus process.

Placebo: sachet of identical appearance and weight containing whole-wheat flour, lily, chrysanthemum and orange-peel powder.

Procedure: both sachets were hung at the head of the bed within 30 cm of the nose from about 23:00 to 07:00 nightly for 9 weeks and replaced every 3 weeks; adherence was supported by a daily calendar record and nightly WeChat reminders. Both groups received the same health education on primary dysmenorrhea.

Sample size: based on a previously reported VAS effect (effect size 0.88, alpha 0.025 two-sided, power 0.90), 68 participants were required, increased by 20% for attrition to 82.

Analysis: within- and between-group comparisons using t-tests or Mann-Whitney/Wilcoxon tests as appropriate.

Safety: participants inhaled the sachet for 5 minutes and were observed for 10 minutes when it was first issued; adverse reactions were monitored throughout.

Inclusion criteria

• Female student enrolled at Sichuan Nursing Vocational College
• Aged 18-25 years, unmarried and nulliparous
• Meets Western and traditional Chinese medicine diagnostic criteria for primary dysmenorrhea
• History of primary dysmenorrhea for more than 6 months, with pain in 3 consecutive menstrual cycles
• Menstrual symptom score greater than 8, moderate or severe dysmenorrhea (VAS at least 3)
• Regular menstrual cycle
• No sedative, analgesic or hormonal medication in the week before enrolment, and willing not to take interfering medication during the study
• Voluntary participation with signed informed consent

Exclusion criteria

• Gynaecological disease (secondary dysmenorrhea) or irregular menstrual cycle
• Planning pregnancy
• Other serious physical or psychiatric illness (e.g., autoimmune disease, cancer, heart disease), or conditions requiring surgery
• Currently participating in another clinical trial
• Unable to complete the study period