Methotrexate is a chemotherapy medication frequently used to treat various forms of cancer. The purpose of this research was to examine if the administration of Arthrospira platensis (Spirulina) and/or thymoquinone could ameliorate the liver injury resulting from methotrexate. The rats were randomly assigned to seven groups, each containing seven rats. The groups included a control group that received only saline, a group that received A. platensis orally at a dose of 500 mg/kg, a group that received thymoquinone orally at a dose of 10 mg/kg, a group that received a single i.p. dose of 20 mg/kg methotrexate, a group that received both A. platensis and methotrexate, a group that received both thymoquinone and methotrexate, and a group that received A. platensis, thymoquinone, and methotrexate. The injection of methotrexate caused an increase in the levels of alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, cholesterol, triacylglycerides, and low-density lipoprotein-cholesterol, and a decrease in high-density lipoprotein-cholesterol (HDL-cholesterol). The liver tissues also showed an increase in malondialdehyde and a decrease in reduced glutathione, superoxide dismutase, and catalase, along with pathological lesions and increased expression of TNF-α and caspase-3. However, administration of A. platensis
and thymoquinone alone or in combination reduced the toxicity and apoptosis induced by methotrexate.