Results
photosensitivity, diarrhoea, nausea, vomiting
PHOTOSENSITIVITY, STIS
Between February 2020 and November 2021, 540 cisgender women were screened for study eligibility and 449 were enrolled (Fig. 
Flow diagram of participant screening and enrolment. (*Other includes age out of study range, breastfeeding, declined study procedures, comorbidities, and not sexually active)The majority of women enrolled (82.4%, 370 women) reported having a primary sex partner in the three months prior to enrolment, and one-third (33.2%, 149 women) reported sex with a new partner in the past three months. A total of 268 (67.5%) women reported not using a condom in the most recent vaginal sex act. Over half (56.6%, 254 women) had tested for HIV together with their male partners. Recent transactional sex, sex in exchange for goods, gifts, or money, was reported by 36.7% (165 women), and 16.7% (75 women) reported drinking alcohol before sex in the past month.
Baseline demographic data, sexual behaviour, contraceptive use, and STI prevalence*Fifty-two participants did not have vaginal sex in the 3 months prior to enrolmentMore than half of the women were using long-acting reversible contraceptives: implant 149 (33.2%), injectable depot-medroxyprogesterone acetate 98 (21.8%), and intrauterine device 11 (2.4%). One hundred women (22.3%) reported not using any modern contraceptive method. Symptoms commonly associated with doxycycline were reported by some participants prior to randomization, including nausea 38 (8.5%), diarrhoea 19 (4.2%), vomiting 13 (2.9%), and photosensitivity 4 (0.9%).Overall, 17.9% of women (80/448) had any bacterial STI, including 14.1% (63/448) with 
Baseline STI prevalence among cisgender women enrolled in a trial of doxycycline postexposure prophylaxis in Kisumu, Kenya**One participant enrolled without baseline vaginal swab collectionParticipants reported being often or sometimes concerned with contracting STIs (44.5%, 200 women) and HIV (38.1%, 171 women) (Fig. 
Risk concerns and perceptions among the 449 women taking HIV PrEP and enrolled in the dPEP Trial