The aim of the study was to investigate whether the administration of a vaginal tablet containing lactose can modulate the bacterial flora of women with bacterial vaginosis (BV).

Design: Double-blind, placebo-controlled randomised trial.

Setting: Women with BV who responded to advertisements in local newspapers and on posters at the Institutions for Education in Health Science in Eastern Jutland, Denmark. These individuals were supplemented with patients enrolled at a gynaecological clinic.

Participants: Forty women with BV diagnosed through the Amsel test. By randomisation, 20 were assigned to receive lactose tablets, and 20 were assigned to receive placebo tablets.

Interventions: Twice daily application of one lactose tablet or placebo tablet for 7 days.

Inclusion Criteria:

• Amsel criteria positive defined as 3/4 of the following: Vaginal discharge, Fishy odor, pH>4.5 and Clue cells in a wet smear.

Exclusion Criteria:

• Not able to provide written informed consent.

Active and inactive tablets were identical. The tablets were packed and labelled by the manufacturer. The key to identity was retained and was disclosed after recruiting all patients. After informed consent, eligible patients drew a closed opaque envelope from a set of envelopes numbered 1-40 and placed in random order. The envelope contained both number labels for medical data-related documents and sample vials and a closed opaque container holding tablets labelled with the sample number.