Vitamin E is relatively nontoxic and is usually well-tolerated. Most adults can tolerate 100 to 800 mg (equivalent to 149 to 1,192 I.U. of d-Alpha Tocopherol) daily without undesirable effects. However, the vitamin (e.g., at dosages exceeding 300 I.U. daily) has rarely caused nausea, diarrhea, abdominal pain/intestinal cramps, fatigue/weakness, headache, dizziness, blurred vision, emotional disturbances, and rash. Myopathy (muscle disorder), hypertension, thrombophlebitis (vein inflammation related to blood clot), gonadal dysfunction, breast soreness/gynecomastia, creatinuria (increased concentration of creatine in the urine), increased serum creatine kinase, serum cholesterol, and triglycerides; increased urinary estrogens and androgens; and thyroid problems have also been noted. These effects generally disappeared after discontinuing the vitamin.
Doses of vitamin E greater than 1,000 mg (equivalent to 1,490 I.U. of d-Alpha Tocopherol) daily for prolonged periods have occasionally been associated with increased bleeding tendency in vitamin K-deficient patients such as those taking oral anticoagulants. It has also been suggested that it may increase the risk of thrombosis in some patients, such as those taking estrogens.