Dosage, Function, Side Effects, etc.
Use
What is warfarin for?
Warfarin is a blood thinner (anticoagulant) drug. This drug works by reducing the formation of blood clots.
Warfarin is a drug used to prevent heart attacks, strokes, and blood clots in the veins and arteries. Warfarin can also be used for purposes not listed in the medication guide.
What are the rules for using warfarin?
Warfarin is a drug that should be used exactly as instructed by your doctor. Follow all directions on your prescription label. Your doctor may change your dose from time to time to make sure you get the best results.
Do not take warfarin in doses that are larger or smaller or for longer than what your doctor instructs you to do.
Take warfarin at the same time every day, with or without food. Never take multiple doses of this medicine.
When using warfarin, you will need to check your “INR” frequently or prothrombin time test (to measure how long it takes your blood to clot). You may not see any change in your symptoms, but your blood work will help your doctor determine how long to give you warfarin. You must remain under a doctor’s care while using this medicine.
If you are receiving warfarin in the hospital, call or visit your doctor 3 to 7 days after you leave the hospital. Your INR will need to be tested at that time. Don’t miss any scheduled appointments with your doctor.
Tell your doctor if you have diarrhea, fever, chills, or flu symptoms, or if your weight changes.
How to store this drug?
This medication is best stored at room temperature, away from direct light and damp places. Don’t keep it in the bathroom. Don’t freeze it. Other brands of this drug may have different storage rules.
Observe the storage instructions on the product package or ask your pharmacist. Keep all medicines away from children and pets.
Do not flush medicines down the toilet or down the drain unless instructed to do so. Discard this product when it has expired or when it is no longer needed.
Consult your pharmacist or local waste disposal company about how to safely dispose of your medicine.
Dose
The information provided is not a substitute for medical advice. ALWAYS consult your doctor or pharmacist before starting treatment.
What is the dosage for warfarin for adults?
The following are the recommended warfarin doses for adults:
Dosage for congestive heart failure
Initial: 2-5 mg orally or intravenously once daily for 1 to 2 days, then adjust dosage according to results of International Normalized Ratio (INR) or prothrombin time (PT).
Maintenance: maintenance dose ranges from 2-10 mg orally or intravenously once a day.
Dosage for thromboembolic stroke prophylaxis
Initial: 2-5 mg orally or intravenously once daily for 1 to 2 days, then adjust dosage according to results of International Normalized Ratio (INR) or prothrombin time (PT).
Maintenance: maintenance dose ranges from 2-10 mg orally or intravenously once a day.
Dosage for myocardial infarction
Initial: 2-5 mg orally or intravenously once daily for 1 to 2 days, then adjust dosage according to results of International Normalized Ratio (INR) or prothrombin time (PT).
Maintenance: maintenance dose ranges from 2-10 mg orally or intravenously once a day.
For more information, you can consult a doctor or medical team.
What is the dosage of warfarin for children?
There is no provision for the dosage of warfarin for children. Warfarin is a drug that can be dangerous for children.
It is important to understand the safety of drugs before use. Consult your doctor or pharmacist for more information.
In what dosage and preparation is this drug available?
Warfarin is available in the following dosages:
Tablets: 1 mg, 2 mg, 2.5 mg, 3 mg, 4 mg, 5 mg, 6 mg, 7.5 mg
Side effects
What side effects might warfarin have?
Seek immediate medical help if you experience any of the following signs of an allergic reaction:
- itchy rash
- difficulty breathing
- swelling of the face, lips, tongue, or throat
Stop using this drug and contact your doctor immediately if you experience serious side effects, such as:
- Pain, swelling, feeling of heat or cold, skin changes, or discoloration anywhere on your body
- Feet suddenly hurts, foot ulcers, toes or fingers turn purple
- Sudden headache, dizziness, or feeling tired
- Unusual bleeding (nose, mouth, vagina, or rectum), bleeding from a wound or needle injection, bleeding that won’t stop
- The underside of the skin bruises easily, and is purple, or red spots
- There is blood in your urine, black or bloody stools, coughing up blood or vomiting that looks like coffee grounds
- Pale skin, lightheadedness or shortness of breath, fast heart rate, trouble concentrating
- Dark, jaundice (yellowing of the skin or eyes)
- Pain in the stomach, back, or sides
- Urinating less than usual or not at all
- Numbness or muscle weakness
- Diarrhea, fever, chills, body aches, or flu symptoms
Other, less serious side effects include:
- Nausea, vomiting, mild stomach pain
- Bloating, gas
- Changes in the sense of taste
Not everyone experiences the side effects mentioned above. There may be some unspecified side effects.
If you have concerns about certain side effects, consult your doctor or pharmacist.
Precautions & Warnings
What to know before using warfarin?
Before using certain drugs, consider the risks and benefits first. This is a decision you and your doctor will have to make.
For the warfarin drug, here are some things you need to pay attention to:
Allergy
Tell your doctor if you have any unusual or allergic reactions to this or any other medicine. Also tell your doctor if you have any other types of allergies such as to food, coloring, preservatives, or animal allergies. For over-the-counter products, read the labels on the packaging carefully.
Elderly
Studies conducted to date have not shown specific problems that will limit the performance of this drug in the elderly.
However, elderly patients may need to be careful in determining the dose, especially those who are at risk of bleeding.
Is this drug safe for pregnant or breastfeeding women?
Quoted from StatPearls, this drug is included in the risk of pregnancy category D according to the US Food and Drug Administration (FDA). The following references the pregnancy risk categories according to the FDA:
- A = Not at risk
- B = No risk in several studies
- C = May be risky
- D = There is positive evidence of risk
- X = Contraindicated
- N = Unknown
Always consult your doctor to weigh the potential benefits and risks before using this medication.
Meanwhile, warfarin can be absorbed into breast milk (ASI) even in small amounts. Therefore, this drug may be taken by a nursing infant.
However, there is no research that confirms if this drug is harmful to a nursing baby. Consult your doctor first if you are breastfeeding and want to take warfarin.
Interaction
What medicines may interact with warfarin?
Drug interactions can change the performance of your medications or increase the risk of serious side effects. Not all possible drug interactions are listed in this document.
Keep a list of all the products you use (including prescription / non-prescription drugs and herbal products) and consult your doctor or pharmacist. Do not start, stop, or change the dose of any medication without your doctor’s approval.
The following are drugs that have the potential to cause interactions with the warfarin you are taking:
- aspirin
- salicylate
- NSAID drugs (ibuprofen, naproxen, celecoxib)
- low-dose aspirin (clopidogrel, ticlopidine)
- paracetamol
- mifepristone
- apixaban
- defibrotide
Can food or alcohol interact with this drug?
Certain drugs should not be used with meals or when eating certain foods because drug interactions can occur.
Smoking tobacco or consuming alcohol with certain drugs can also cause interactions to occur. Discuss your use of drugs with food, alcohol, or tobacco with your health care provider.
According to Drugs.com, here are foods or drinks that could potentially trigger interactions with warfarin:
- green tea
- high protein foods
- Pomelo
- foods that contain vitamin K
What health conditions can interact with this drug?
Any other health conditions you have can affect the use of this drug. The following are some of the health conditions that may interact with warfarin:
- History of alcohol abuse or dependence
- Mental disorders (for example, psychosis or dementia)
- Blood disease or bleeding problems
- Liver infection
- Hypertension (high blood pressure)
- Spinal anesthesia
- Ulcers in the stomach or intestines
- Stroke
- Have recently had surgery, or are scheduled to have surgery (for example, eye, brain, or spinal surgery)
- Threatened with a miscarriage
- Catheter insertion
- Congestive heart failure
- Deep-vein thrombosis (DVT)
- Diabetes
- Fall or hit
- Infection
- Kidney illness
- Liver disease
- Operation
- Thrombocytopenia
- Trauma
Overdose
What should I do in an emergency or overdose?
In case of an emergency or overdose, contact the local emergency services provider (119) or immediately to the nearest hospital emergency department.
What should I do if I miss a dose?
If you forget a dose of this medicine, take it as soon as possible. However, when it is nearing the time of the next dose, skip the missed dose and return to the usual dosing schedule. Don’t double the dose.
Hello Health Group does not provide medical advice, diagnosis or treatment.
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Sinha, S. (2019). Warfarin – Drugs.com. Retrieved March 3, 2021, from https://www.drugs.com/warfarin.html
Warfarin SODIUM – WebMD. (nd). Retrieved March 3, 2021, from http://www.webmd.com/drugs/2/drug-3949/warfarin-oral/details
Patel, S., Singh, R., Preuss, C., & Patel, N. (2020). Warfarin. Retrieved March 3, 2021, from https://www.ncbi.nlm.nih.gov/books/NBK470313/
Warfarin – NHS. (2019). Retrieved March 3, 2021, from http://www.nhs.uk/conditions/Anticoagulants-warfarin-/Pages/Introduction.aspx
Cunha, J. (nd). Warfarin – RxList. Retrieved March 3, 2021, from https://www.rxlist.com/consumer_warfarin_coumadin_jantoven/drugs-condition.htm
Warfarin, Oral Tablet – Healthline. (2018). Retrieved March 3, 2021, from https://www.healthline.com/health/warfarin-oral-tablet#take-as-directed
