Serious. These medicines may interact and cause very harmful effects. Contact your healthcare professional (e.g. doctor or pharmacist) for more information.
How the interaction occurs:
When these two medicines are taken together, probenecid may cause your body to process methotrexate more slowly.
What might happen:
Your blood levels of methotrexate may increase and cause toxic effects.
What you should do about this interaction:
Contact your doctor as soon as possible if you are taking these two medicines. Your doctor may monitor your methotrexate blood levels and the dosage may need to be adjusted.If you feel unusually drowsy, have blurred vision, headaches, stomach pain, fever, chills, rashes, mouth sores, nausea or vomiting, contact your doctor.Make sure that your doctor knows all of the medicines that you are taking. Your healthcare professionals (e.g. doctor or pharmacist) may already be aware of this interaction and may be monitoring you for it. Do not start, stop, or change the dosage of any medicine before checking with them first.
1.Israili ZH, Soliman AM, Cunningham RF, Plowden JF, Keller JW. The interaction of methotrexate and probenecid in man and dog. Proc Am Assoc Cancer Res 1978;19:194.
2.Aherne GW, Piall E, Marks V, Mould G, White WF. Prolongation and enhancement of serum methotrexate concentrations by probenecid. Br Med J 1978 Apr 29;1(6120):1097-9.
3.Howell SB, Olshen RA, Rice JA. Effect of probenecid on cerebrospinal fluid methotrexate kinetics. Clin Pharmacol Ther 1979 Nov;26(5):641-6.
4.Lilly MB, Omura GA. Clinical pharmacology of oral intermediate-dose methotrexate with or without probenecid. Cancer Chemother Pharmacol 1985; 15(3):220-2.
5.Basin KS, Escalante A, Beardmore TD. Severe pancytopenia in a patient taking low dose methotrexate and probenecid. J Rheumatol 1991 Apr; 18(4):609-10.