Final answer:
The correct understanding of methotrexate treatment is that the patient will avoid crowds to minimize infection risk due to the drug's immunosuppressive effects. Supplementing with folic acid to mitigate side effects is common, and regular lab monitoring is necessary.
Step-by-step explanation:
The correct statement by the client that indicates an understanding of methotrexate therapy for systemic lupus erythematosus would be 'I will avoid interacting with people in large crowds.' This demonstrates an understanding that methotrexate is an immunosuppressive agent and can lower the body's ability to fight infections, which makes avoiding large crowds a precaution to reduce the risk of catching an infection.
It is incorrect to say that vitamin supplements containing folic acid should not be taken; in fact, they are often prescribed concurrently with methotrexate to mitigate its side effects like folic acid deficiency. Methotrexate inhibits folic acid reductase, which is critical for DNA synthesis and cell division, and supplementation with folic acid can help manage side effects. Additionally, routine lab work is necessary to monitor for potential toxic effects of methotrexate, including hepatic, pulmonary, and hematologic effects. Hence, the statement 'Lab work won't be necessary while I take this medication' reflects a misunderstanding of the medication.