Background In Kenya Mass Drug Administration (MDA) intervention with single dose of Diethylcarbamazine Citrate (DEC) and Albendazole (ABC) commonly referred to as DA. has been in use since 2002 the control of Lymphatic Filariasis(LF), however no safety surveillance has been conducted before. Recently, the Neglected Tropical Disease (NTD) Program, piloted the use of Ivermectin (IVM), Diethylcarbamazine and Albendazole known as IDA triple therapy in two highly endemic counties.

Methodology This was a longitudinal community-based cohort event monitoring 10,010 and 10, 411 eligible participants in Kilifi and Mombasa Counties respectively. Adverse event monitoring and grading was actively done at 24 hours, 48 hours and at day 7 following mass drug administrations. The collected data was analysed for incidence, types, and predictors of adverse events.

Results A total of 5807 and 3102 AEs were reported by 2839 and 1621 individuals in the IDA and DA groups, respectively. The incidence of experiencing one or more AEs was significantly higher (p<0.0001) in IDA (27.3%; 95%CI, 26.4%-28.2%) compared to DA (16.2%;95%CI, 15.5–16.9%) group. The three most AEs reported among those who took IDA were dizziness (15.9%), drowsiness (10.10%) and headache (6.5%), compared to DA that reports dizziness (5.9%), headache (5.6%) and loss of appetite (3.3%). Female sex, taking ≥ 3 tablets of DEC or IVM, older age, taking concurrent medications, ≥3 tablets of DEC, and type of meal taken before MDA were significant predictors of AEs. The AEs were systemic, mild to moderate and transient.

Conclusion Both the dual Therapy with DA and triple therapy with IDA were generally safe and well as MDA regimens for Elimination of LF. The incidence of experiencing one or more type AEs is about two-fold higher with IDA than with DA. The integration of safety monitoring during MDA is critical for the timely detection and management of reported AEs.