How menstrual pads, tampons, and cups affect vaginal health

IMVAHA: Improving Menstrual and VAginal Health for All

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

• Phase: Not applicable
• Study type: Interventional
• Enrollment: 100 (estimated)
• Ages: 18 Years to 35 Years
• Sex: Female
• Sponsor: Swiss Tropical & Public Health Institute (Academic / other)
• Locations: 3 sites (Yaoundé, Yaoundé and 2 other locations)
• Trial ID: NCT06646185 on ClinicalTrials.gov

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.

Who should consider this trial

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.

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.

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 performed: 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.

Eligibility 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 this trial is running

Yaoundé, Yaoundé and 2 other locations

• 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

Conditions Effects of Menstrual Products on the Vaginal Microbiome; vaginal microbiome; menstruation; crossover study; menstrual products