Nurofen is the Australian name for Ibuprofen and the the following is what is sited about interactions between the drugs you mentioned.

MONITOR CLOSELY: Coadministration with nonsteroidal anti-inflammatory drugs (NSAIDs) may increase the plasma concentrations and toxicities of methotrexate. The proposed mechanism is NSAID inhibition of the renal elimination of methotrexate and its metabolite, 7-hydroxymethotrexate, although data from pharmacokinetic studies are inconsistent and conflicting. Displacement of methotrexate binding to serum albumin by certain NSAIDs may also play a secondary role. Unexpectedly severe and sometimes fatal bone marrow suppression, aplastic anemia, gastrointestinal toxicity, and nephrotoxicity have been reported during concomitant administration of methotrexate with NSAIDs. The risk is greatest in patients receiving high dosages of methotrexate and those with renal impairment. In clinical studies, methotrexate at dosages of 7.5 to 15 mg/week has been used without apparent problems in patients with rheumatoid arthritiswho also received constant dosage regimens of NSAIDs. However, there have been occasional reports of stomatitis, pneumonitis, bone marrow toxicity, and fatality in patients receiving low-dose weekly methotrexate with daily NSAIDs.

MANAGEMENT: NSAIDs should generally not be administered prior to or concomitantly with high dosages of methotrexate, such as those used to treat osteosarcoma. Caution should be exercised when NSAIDs are administered concomitantly with lower dosages of methotrexate. Close monitoring for signs and symptoms of bone marrow suppression, nephrotoxicity, and hepatotoxicity is recommended during treatment. Patients should be advised to contact their physician if they develop stomatitis, nausea, vomiting, diarrhea, rash, anorexia, jaundice, dark urine, dry cough, shortness of breath, and/or signs and symptoms of myelosuppression such as pallor, dizziness, fatigue, lethargy, fainting, easy bruising or bleeding, fever, chills, sore throat, body aches, and other influenza-like symptoms. Patients should also be counseled to avoid any other over-the-counter NSAID products.

Methotrexate may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

• dizziness

• drowsiness

• headache

• swollen, tender gums

• decreased appetite

• reddened eyes

• hair loss

Some side effects can be serious. If you experience any of these symptoms or those listed in the IMPORTANT WARNING section, call your doctor immediately:

• blurred vision or sudden loss of vision

• seizures

• confusion

• weakness or difficulty moving one or both sides of the body

• loss of consciousness

Methotrexate may cause other side effects. Call your doctor if you have any unusual problems while taking this medication.

I did not see any Side Effect of diarrhea.

This is a serious drug, any questions you may have, contact your doctor.

If you are taking it methotrexate for rheumatoid arthritis, you are doing it to reduce the destructive effects that your own immune system is having on cartilage in your joints and other connective tissue. Methotrexate need to be taken along with folic acid as it takes folic acid out of the system. People that use methotrexate need to be checked regularly with blood test to see if there is any toxin build up in the kidneys. However if you have been incorrectly diagnosed it hardly matters as the side effects ( and there are heaps of them) would be the same either way.

No. It is a drug which prevents cells dividing and is usually used for cancer, psoriasis and rheumatoid arthritis. It's only use around fertile women who may be pregnant is to induce miscarriage in cases of ectopic pregnancy. If taken during a possibly normal pregnancy it can cause severe birth defects.