How menstrual pads, tampons, and cups affect vaginal health
Official title: IMVAHA: Improving Menstrual and VAginal Health for All
Run by Swiss Tropical & Public Health Institute · NCT06646185 · Data updated 2026-11-12
We will test whether using pads, tampons, or menstrual cups for two menstrual cycles each changes the types and amounts of vaginal bacteria in people who menstruate aged 18–35 in Peru, Cameroon, and Switzerland.
Quick facts
| Study type | Interventional |
|---|---|
| Ages | 18 Years to 35 Years |
| Sex | Women only |
| Enrollment | 100 (estimated) |
| Sponsor | Swiss Tropical & Public Health Institute Academic / other |
| Locations | 3 sites (Yaoundé, Yaoundé and 2 other locations) |
| Status | Recruiting |
| Started | April 15, 2026 |
| Main results expected | December 31, 2026 |
| Study ends | December 31, 2026 |
| Registry record updated | April 23, 2026 |
| Trial ID | NCT06646185 on ClinicalTrials.gov |
Is this trial a fit for you?
✓Likely a good fit
People aged 18–35 with regular 21–35 day menstrual cycles who live in the recruitment regions, can read a local study language, and are willing to use pads, tampons, and a menstrual cup for six months are the best candidates.
✕Probably not a fit
Those who are pregnant, breastfeeding, trying to conceive, have recent antibiotic or vaginal antifungal use, have irregular or abnormal cycles, or cannot commit to using all three products for six months are unlikely to benefit from participation.
A plain-English reading of the study's rules. Only the study team can confirm whether you qualify.
What this trial studies
This randomized three-period crossover trial has participants use pads, tampons, and menstrual cups in randomized orders, each for two consecutive menstrual cycles, for a total of six months. Participants are assigned to one of six product sequences and self-collect vaginal swabs at three time points during each menstrual cycle; samples will undergo 16S rRNA gene sequencing to determine bacterial composition. The trial is conducted at sites in Peru, Cameroon, and Switzerland with kits and products provided for six consecutive cycles. Because each participant uses all three products in different periods, comparisons are made within individuals rather than against a separate control group.
Why it matters
Potential benefit: If successful, the results could help people choose menstrual products that support a healthier vaginal microbiome.
How similar studies have gone: Smaller observational and short-term intervention studies have suggested menstrual products can alter vaginal bacteria, but large randomized crossover trials across multiple countries are limited.
Who can join: the full rules
Show full inclusion / exclusion criteria
Inclusion Criteria: * able to provide informed consent; * aged 18-35; * residing in the recruitment region and expecting to reside in the same region for at least six months following recruitment (Yaoundé/ Gounougou, Cameroon; Loreto/Lima/Maynas provinces, Peru; or Basel-Landschaft and Basel-Stadt cantons, Switzerland); * are native speakers or are able to read and understand one of the following languages in each respective country (German, French, Italian, English or Spanish in Switzerland; French or English in Cameroon; Spanish in Peru); * had menstrual cycles of 21-35 days for at least the last 4 months; * had menses which lasted at least 3 days for at least the last 4 months. Exclusion criteria: * experienced a menstrual abnormality with any of the menstrual cycles in the last 4 months (such as oligomenorrhea or amenorrhea, or bleed more than 7 days a month); * are pregnant or actively trying to become pregnant; * are breastfeeding; * used antibiotics and/or vaginal antifungals in the last 30 days prior to recruitment; * had a vaginal birth in the last 6 months; * vaginal surgery, perineal surgery, uterine surgery, miscarriage or abortion in the last 6 months; * history of Toxic Shock Syndrome ; * positive to detection of the toxic shock syndrome toxin-1 gen (tst) using Polymerase Chain Reaction (PCR); * Intrauterine device in situ; * under medication (treatment against infectious or chronic disease) at the time of recruitment or during the 3 weeks prior to recruitment; * clinical symptoms of vaginal infection; * smoker.
Where it's running
-
Centre de Recherche sur les Maladies Emergentes et Re-Emergentes
Yaoundé, Yaoundé, Cameroon Recruiting -
Universidad Nacional de la Amazonia Peruana
Iquitos, Iquitos, Peru Recruiting -
Swiss Tropical and Public Health Institute
Allschwil, Allschwil, Switzerland Recruiting
Study contacts
- Principal investigator: Sonja Merten, PhD — Swiss Tropical & Public Health Institute
- Study coordinator: Sonja Merten, MD MPH PhD
- Email: sonja.merten@swisstph.ch
- Phone: 0041-61-284-8387
How to take part
- Review the eligibility criteria above with your treating physician.
- Check the official listing on ClinicalTrials.gov for the latest contact details and recruitment status.
- Contact the study coordinator or principal investigator to ask for pre-screening. Pre-screening is free and never obligates you to enroll.