The public advertisement with indiscriminate sale of herbal bitters has led to increase in consumption without adequate information on the safety profile of the product. Thus, this study aimed to investigate the effects of HB cleanser® bitters (a polyherbal mixture composing of Aloe vera, Acinos arvensis, Moringa oleifera, Chenopodium murale and Cinnamomum aromaticum, Allium sativum on haematological parameters in Wistar rats. Twenty-eight animals were randomly allotted into 4 groups comprising 7 animals each. HB cleanser® bitters was administered at doses of 1 ml/kg, 1.03 ml/kg and 1.29 ml/kg according to the manufacturers recommendation while the fourth group was administered with normal saline orally for 28days consecutively. Feed and fluid intake were measured daily. Haematological parameters (PCV, RBC, WBC, HB, platelet, neutrophil, lymphocyte, monocyte, eosinophil, and basophil) were evaluated. Flavonoids, saponins and cardiac glycosides were revealed as the phytoconstituents. The results showed that the HB cleanser bitters at 1.03 ml/kg significantly (P0.05) decrease in RBC, PCV and Hb (4.88 ± 0.14 ×1012/L, 44.40 ± 1.17%, 14.54 ± 0.55 g/dl) when compared to control. A non-significant increase in platelets occurred at all doses. The findings of this study have shown that HB cleanser® bitters caused an increase in white blood cell count with a reduction in haemoglobin concentration and red blood cell count hence, it should be taken with caution.