Leucopenia, thrombocytopenia, anaemia, mouth ulceration, stomatitis, diarrhea. Bone marrow depression, megaloblastic anaemia. Hypogammaglobulinaemia. Liver & kidney damage. Osteoporosis, effects on skin & nails, pulmonary reactions including interstitial pneumonitis. Metabolic alterations; neurotoxic reactions; teratogenic effects.