Introduction Ivermectin and Albendazole (IA) are drug combinations used in mass drug administration (MDA) to halt transmission of lymphatic filariasis (LF) in endemic communities. Safety data on haematological and biochemical changing patterns following MDA is limited. We investigated changes in such parameters among individuals exposed to IA during MDA in rural Tanzania.

Methods An analytical cross-sectional study was conducted amongst 498 individuals whose blood samples were collected before and after MDA. Complete blood count, renal and liver function tests were done at day 0 and 7. Wilcoxon signed rank and McNemar tests were used to compare the median and proportion of individuals with abnormal values respectively, before and after MDA.

Results The overall findings indicate changes in some parameters after IA intake. The median values of haematological parameters to include RBC, Hb, and HCT decreased and MCH and MCHC increased significantly in both FTS positive and negative individuals following MDA (p<0.05). Platelet counts to include PDW, MPV and PLCR all increased after drug intake in both groups (p<0.05). Biochemical parameters to include ALT and BilD decreased in both groups whilst AST increased in FTS positive (from 24.4 U/L to 25.35 U/L, p=0.01) and decreased in FTS negative individuals (from 24.95 U/L to 24.55 U/L, p=0.04). A significant proportion of individuals had haematological parameters below reference range (RBC 8.2%, p=0.01; Hb 23.5%, p=0.002; HCT 32.9% p<0.001; MCH 9.8%, p<0.001; and MCHC 0.5%, p<0.001). Sex was the only predictor of low Hb levels with females at a higher risk of experiencing low Hb than males (aOR: 3.16, 95% CI= 1.29–7.76, p=0.01).

Conclusion Our findings demonstrate that haematological changes may occur following IA MDA. No significant changes in biochemical (kidney and liver function test) parameters were observed after drug use. Overall, the observed abnormalities were minor with minimal clinically relevant safety concerns.