Methotrexate: Binding of methotrexate to dihydrofolate reductase reduces nucleotide synthesis as well as amino acids serine and methionine. Folinic acid rescue is usually given after methotrexate therapy (e.g. 24 hours) to reduce myelosuppression side effects.

Methotrexate is associated with interstitial pneumonitis. This is rare but a serious complication. Chest radiography reveals a diffuse interstitial or mixed interstitial and alveolar infiltrate, with a predilection for the lower lung fields.

Common side effects of gold are mouth ulceration, leucopenia, proteinuria and skin rashes.