was successfully added to your cart.

Side Effects of Coumadin (Warfarin)


Description: Warfarin, also known by its trade names Coumadin and Jantoven, is an anticoagulant medication. It is commonly used to prevent thrombosis (the formation of a clot). Patients are prescribed the drugs for medical conditions that elevate the risk of developing thrombosis or a thromboembolism.

Serious Side Effects of Warfarin

As an anticoagulant, warfarin has a number of hematologic side effects. The most serious of these is fatal or nonfatal hemorrhage, which may present as:

  • Paralysis
  • Paresthesia (pins and needles)
  • Headache
  • Muscle pain (Myalgia)
  • Dizziness
  • Shortness of breath
  • Other severe adverse reactions include skin necrosis (skin death), purple toe syndrome, gangrene, foot ulcers and high blood pressure.
    (Warfarin label as reported by the U.S. Food and Drug Administration, 2010).

    Less Common Side Effects of Warfarin

    Uncommon side effects of warfarin include:

  • Urticaria (itching)
  • Rash
  • Alopecia (baldness)
  • Vomiting
  • Nausea
  • Diarrhea
  • Cramps
  • Flatulence (excessive gas)
  • Priapism (painful erection)
  • (Warfarin label as reported by the FDA, 2010).

    Understand Your Risks with the Rxight® Genetic Test

    Most patients suffer no symptoms from warfarin therapy, while other are not as fortunate. This inter-patient variability has been associated with the different genetic profiles of individual patients. Polymorphisms in genes encoding receptors or enzymes that the drug directly acts on have been associated with an increased risk of developing side effects. Rxight® genetic testing identifies how well you metabolize warfarin based on your genetic makeup and therefore enables your prescriber to adjust the dosing to avoid side effects and achieve optimal efficacy. Moreover, Rxight® analyzes hundreds of other clinically relevant prescription and over-the-counter medications, providing a “medication blueprint” for life. With the results of genetic testing, you and your medical team can find the safest and most effective right dose, preferably ahead of time, to avoid potentially dangerous complications.


    Contributors to this Article:
    Michael Sapko, MD, PhD; and Deborah Kallick, PhD, Medicinal Chemistry

    Read more about Rxight® Pharmacogenomics