Which of the following is a side effect of methotrexate?

Methotrexate is a medication frequently used in the treatment of various conditions such as rheumatoid arthritis, psoriasis, and certain types of cancers. One important side effect of methotrexate is macrocytic anemia. This occurs due to its mechanism of action as a folate antagonist, which inhibits the synthesis of DNA and RNA. Since folate is crucial for the production of red blood cells, inadequate folate levels can lead to impaired erythropoiesis, resulting in macrocytic anemia—characterized by the presence of abnormally large red blood cells.

Patients on methotrexate are often monitored for blood counts, particularly because anemia can develop as a result of this medication's interference with folate metabolism. Macrocytic anemia can manifest with symptoms like fatigue, weakness, and paleness, among others, emphasizing the importance of recognizing this potential toxicity in those receiving treatment with methotrexate. Monitoring and supplementation of folate can mitigate this side effect in many patients.

The other options do not have a well-established connection to the use of methotrexate. Hypercalcemia is not directly caused by methotrexate and is more associated with certain malignancies. Constipation is not a common side effect linked with this medication,