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Warfarin Side Effects

For the Consumer

Applies to warfarin: oral tablet

Along with its needed effects, warfarin may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking warfarin:

Less common
  • Bleeding gums
  • blood in the urine
  • bloody stools
  • blurred vision
  • burning, crawling, itching, numbness, prickling, "pins and needles", or tingling feelings
  • chest pain or discomfort
  • confusion
  • coughing up blood
  • difficulty with breathing or swallowing
  • dizziness, faintness, or lightheadedness when getting up suddenly from a lying or sitting position
  • excessive bruising
  • headache
  • increased menstrual flow or vaginal bleeding
  • nosebleeds
  • paralysis
  • peeling of the skin
  • prolonged bleeding from cuts
  • red or black, tarry stools
  • red or dark brown urine
  • stomach pain with cramping
  • sweating
  • unexplained swelling
  • unusual tiredness or weakness
Rare
  • Arm, back, or jaw pain
  • blue-green to black skin discoloration
  • blue or purple toes
  • change in consciousness
  • chest tightness or heaviness
  • chills
  • clay-colored stools
  • diarrhea
  • dizziness
  • fainting or loss of consciousness
  • fast or irregular breathing
  • fast or irregular heartbeat
  • fever
  • itching or skin rash
  • light-colored stools
  • loss of appetite
  • nausea and vomiting
  • pain in the toes
  • pain, redness, or sloughing of the skin
  • pale skin
  • purplish red, net-like, blotchy spots on the skin
  • skin blisters
  • small red or purple spots on the skin
  • stomach pain
  • swelling of the eyes or eyelids
  • troubled breathing with exertion
  • unpleasant breath odor
  • unusual bleeding or bruising
  • upper right stomach pain
  • vomiting of blood
  • yellow eyes and skin

Some side effects of warfarin may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

Less common
  • Joint pain
  • muscle pain
Rare
  • Bloated
  • change in taste, or bad, unusual, or unpleasant (after) taste
  • cold intolerance
  • excess air or gas in the stomach or intestines
  • full feeling
  • general feeling of discomfort or illness
  • hair loss or thinning of the hair
  • hives or welts
  • lack or loss of strength
  • pain
  • passing gas
  • red, sore, or itching skin
  • sores, welting, or blisters
  • unusual drowsiness, dullness, or feeling of sluggishness

For Healthcare Professionals

Applies to warfarin: compounding powder, intravenous powder for injection, oral tablet

General

The most common adverse reactions were fatal and nonfatal hemorrhage from any tissue or organ.[Ref]

Cardiovascular

Frequency not reported: Hemorrhage, purple toes syndrome, infarction, systemic cholesterol microembolization, vasculitis, systemic atheroemboli[Ref]

Nervous system

Frequency not reported: Cerebral hemorrhage, cerebral subdural hematoma, lethargy, headache, dizziness, taste perversion, paresthesia[Ref]

Gastrointestinal

Frequency not reported: Gastrointestinal hemorrhage, rectal hemorrhage, hematemesis, pancreatitis, diarrhea, nausea, vomiting, melena, abdominal pain, cramping, flatulence, bloating[Ref]

Dermatologic

Frequency not reported: Rash, alopecia, purpura, erythematous swollen skin patches, ecchymosis, skin necrosis, dermatitis, bullous eruptions, urticaria, pruritus[Ref]

Musculoskeletal

Frequency not reported: Tissue necrosis, chills[Ref]

Metabolic

Frequency not reported: Calciphylaxis, edema[Ref]

Respiratory

Frequency not reported: Hemothorax, epistaxis, tracheal or tracheobronchial calcification[Ref]

Genitourinary

Frequency not reported: Hematuria[Ref]

Hematologic

Frequency not reported: Unexplained decrease in hematocrit, hemoglobin decreased[Ref]

Hepatic

Frequency not reported: Jaundice, hepatic dysfunction, hepatitis, cholestatic hepatic injury, liver enzymes elevated[Ref]

Immunologic

Frequency not reported: Hypersensitivity, allergic reactions, anaphylactic reactions[Ref]

Other

Frequency not reported: Fever, fatigue, malaise, asthenia, pain, cold intolerance, feeling cold[Ref]

References

1. Cerner Multum, Inc. "Australian Product Information." O 0

2. "Product Information. Coumadin (warfarin)." DuPont Pharmaceuticals, Wilmington, DE.

3. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0

Some side effects of warfarin may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA.

Disclaimer: Every effort has been made to ensure that the information provided is accurate, up-to-date and complete, but no guarantee is made to that effect. In addition, the drug information contained herein may be time sensitive and should not be utilized as a reference resource beyond the date hereof. This material does not endorse drugs, diagnose patients, or recommend therapy. This information is a reference resource designed as supplement to, and not a substitute for, the expertise, skill , knowledge, and judgement of healthcare practitioners in patient care. The absence of a warning for a given drug or combination thereof in no way should be construed to indicate safety, effectiveness, or appropriateness for any given patient. Drugs.com does not assume any responsibility for any aspect of healthcare administered with the aid of materials provided. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the substances you are taking, check with your doctor, nurse, or pharmacist.

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