Blood Coagulation
Mechanism of Action
Side Effects
The Future

Side Effects

Like any drug, warfarin has its set of  side effects and risks.Some of these are listed below.
  • Haemorrhage : One of the most serious risk associated with anticoagulant therapy with warfarin is haemorrhage (bleeding) in any tissue or organ. The signs, symptoms and severity will vary according to the location and degree of bleeding. Haemorrhagic complications may present as headache, hypotension, chest, abdomen and muscle pain.
  • Necrosis of the skin or ither tissues :  this is the death of  a portion of tissue or an organ of the body. It is caused when not enough blood is supplied to the tissue, whether from trauma or chemicals. Once necrosis is confirmed, it is not reversible. When larger areas of tissues are dead, the tissue is called gangrene.
  • Purple Toes Syndrome : a complication of oral anticoagulation characterised by painful, purplish coloured  toes. While this syndrome is reported to be reversible, some cases progress to necrosis or gangrene.
  • Othe adverse reactions may include fever, urticaria, taste perversions, rash, dark urine, sores in mouth or throat. Priapism (painful abnormal penile erection without sexual desire) has also been associated with anticoagulant administration, however, a causal relationship has not been established.
  • Pregnancy : Warfarin is contraindicated in women who are or may become pregnant because the drug passes through the placental barrier and may cause fatal haemorrhage to the foetus in utero. Furthermore, there have been reports of birth malformations in children born to mothers who have been treated with warfarin during pregnancy.
Warfarin is what's termed a Narrow Therapeutic Range (NTR) drug, which means that the dose has to be adjusted very exactly and individually for each patient in order to avoid adverse effects. Also, as mentioned previously, warfarin interacts with a  large number of drugs and food, which can potentiate or inhibit its effects and cause adverse reactions. Thus patients must be kept under constant monitoring to ensure that the levels of warfarin in the body are within the therapeutic range.