Symptoms of overdose include drops in magnesium, calcium and potassium levels. More severe overdoses can cause heart rhythm problems, since the anticoagulant reduces the amount of oxygen that the blood can carry. Difficulties with liver and kidney function can also result due to the inhibition of the cleaning properties of these organs. The outward appearances of the patient can include an increase in bruising and bleeding as blood vessel walls lose the ability to carry blood. Medical attention should be given quickly to prevent the further possiblity of seizures or death.