Oral anticoagulants: Safety checks

Anticoagulant medicines are widely used to reduce risk of blood clots and strokes. Here's a checklist for safe use of anticoagulant medicines.

Anticoagulant medicines are widely used to reduce risk of blood clots and strokes. Here's a checklist for safe use of anticoagulant medicines.

Use this summary to help prepare for a discussion about the safe use and monitoring of oral anticoagulants. Any issues identified should be recorded in the patient record as part of usual clinical practice.

View the TGA-approved Product Information or Consumer Medicines Information (CMI) leaflet for each anticoagulant for complete details.


Safety checks for all anticoagulants

For all oral anticoagulants, including warfarin, apixaban (Eliquis), dabigatran (Pradaxa) and rivaroxaban (Xarelto), patients should look out for warning signs of a bleed or blood clot between visits.

In addition to monitoring for emergency or worrying side effects (see below), patients need to consider:

  • Have any of my medicines been started, stopped or changed?
  • Have I had any difficulties taking the anticoagulant as prescribed?
  • Do I need to have surgery or a procedure (including dental)?
  • Am I planning to to have a baby?

For all oral anticoagulants, look out for these side effects1-3

Emergency side effects

These side effects can be warning signs of a serious bleed or blood clot.

  • Blood in the urine or stool
  • Breathlessness or chest pain
  • Coughing up or vomiting blood
  • Dizziness or fainting
  • Exceptional weakness or unexplained swelling
  • Heavy menstrual bleeding
  • Signs of allergy (eg, rash, itching, hives, swelling, wheezing, difficulty breathing)
  • Numbness in the arms or legs
  • Oozing from a surgical wound
  • Prolonged or excessive bleeding (eg, from gums, nose)
  • Signs of liver problems (eg, yellowing of the skin and/or eyes)

Recommendation: Patients should immediately see a doctor, or immediately go to Accident and Emergency at the nearest hospital.

Worrying side effects

These side effects are usually mild.

  • Bruising
  • Constipation
  • Cough
  • Diarrhoea, indigestion or stomach pain
  • Fast heart beat
  • Fever
  • Headache
  • Mild rash or itchy skin
  • Nausea
  • Nose bleeds
  • Pain in the arms or legs
  • Painful swollen joints
  • Sore nasal passages or throat
  • Tiredness, pale skin and breathlessness

Recommendation: Patients should immediately tell a doctor if they experience any of these effects.


Monitoring with NOACs

The non-vitamin K antagonist oral anticoagulants (NOACs) do not require routine anticoagulation monitoring and have fewer food and drug interactions than warfarin does.4

However, patients taking a NOAC need to have their kidney function to be monitored throughout treatment.5 Kidney function should be checked at least annually, and whenever clinical circumstances or medicines change. If patients have impaired kidney function, monitoring should be more frequent.

It is still also essential to check for potentially harmful drug interactions, contraindications and other patient-related safety factors (such as persistent hypertension, risk of falls, anaemia, and patient adherence) before commencing a NOAC.5

Key questions to consider in patients taking a NOAC include:5

  • Were kidney and liver function assessed when the patient started their NOAC?
  • Has kidney function been checked in the last year?
  • Have clinical circumstances or medicines changed?
  • Has kidney function deteriorated, requiring more frequent monitoring?

For related information summaries, see NOAC indications and PBS listings and NOAC metabolism and interactions.


Monitoring with warfarin

For safe and effective treatment, patients using warfarin need routine anticoagulation monitoring using the international normalised ratio (INR), as well as dose adjustments to compensate for food–drug and drug–drug interactions.4

The recommended INR range for patients taking warfarin for treatment of deep vein thrombosis, pulmonary embolism or stroke prevention in atrial fibrillation is 2.0 to 3.0.4,6-9

Key questions to consider for patients taking warfarin include:10

  • Is the most recent INR within target range?
  • Are there any factors that may influence the INR (see Tables 1 and 2)?
  • Have warfarin brands been switched (bioequivalence of warfarin brands has not been established)?

Table 1. Endogenous factors that may influence the INR response10

Factors increasing INR Factors decreasing INR
  • Blood dyscrasias
  • Cancer
  • Collagen vascular disease
  • Congestive heart failure
  • Diarrhoea
  • Hepatic disorders
  • Elevated temperature
  • Infectious hepatitis
  • Jaundice
  • Hyperthyroidism
  • Poor nutritional state
  • Steatorrhoea
  • Vitamin K deficiency
  • Hereditary coumarin resistance
  • Hyperlipaemia
  • Hypothyroidism
  • Nephrotic syndrome
  • Oedema

Table 2. Exogenous factors that may influence the INR response10

Factors increasing INR   Factors decreasing INR Factors increasing or decreasing INR
  • Adrenergic stimulants (central)
  • Alcohol abuse reduction preparations
  • Aminoglycosides (oral)
  • Anaesthetics (inhaled)
  • Analgesics
  • Anticoagulants
  • Antimalarial agents
  • Antiparasitics/antimicrobials
  • Antiplatelet drugs/effects
  • Beta-adrenergic blockers
  • Cephalosporins (parenteral)
  • Cholelitholytic medicines
  • Diabetes medicines (oral)
  • Ulcerative colitis medicines
  • Gout medicines
  • Haemorrheologic medicines
  • Hepatotoxic medicines
  • Hyperglycaemic medicines
  • Hypertensive emergency agents
  • Macrolides
  • Monoamine oxidase inhibitors
  • Narcotics (prolonged)
  • Non-steroidal anti-inflammatory drugs
  • Psychostimulants
  • Penicillins (intravenous, high dose)
  • Quinolones (fluoroquinolones)
  • Sulphonamides (long acting)
  • Salicylates
  • Selective serotonin reuptake inhibitors
  • Steroids (anabolic)
  • Tetracyclines
  • Thrombolytics
  • Thyroid medicines
  • Uricosuric medicines
  • Vaccines
  • Adrenal cortical steroid inhibitors
  • Antacids
  • Anti-anxiety medicines
  • Antihistamines
  • Antithyroid medicines
  • Barbiturates
  • Enteral nutritional supplements
  • Immunosuppressants
  • Oral contraceptives (containing oestrogen)
  • Anti-arrhythmics
  • Antibiotics
  • Anticonvulsants
  • Antidepressants
  • Antineoplastics
  • Antipsychotic medicines
  • Antithyroid medicines
  • Diuretics
  • Fungal medicines (systemic)
  • Gastric acidity/peptic ulcer medicines
  • Hypnotics
  • Hypolipidaemics
  • Steroids (adrenocortical)
  • Tuberculosis medicines
  • Vitamins

What patients need to know

Any patient taking a NOAC or warfarin should understand what the medicine is for, why they are taking it, the dose, and its expected benefits and adverse effects. Patients may consider carrying an alert card so that health professionals are aware they are on anticoagulant treatment.11

They should have a plan for:5

  • what to do in case of bleeding
  • what to do if they sustain a serious injury or fall
  • how often monitoring is needed (if applicable)11
  • taking medicines as prescribed and what to do if they miss a dose
  • making any dose adjustments that are required between visits
  • keeping to any special dietary requirements
  • regular clinical review by their doctor.


  1. Bayer Australia Ltd. Rivaroxaban (Xarelto) consumer medicine information (accessed 25 October 2020).
  2. Bristol-Myers Squibb Australia Pty Ltd. Apixaban (Eliquis) consumer medicine information (accessed 25 October 2020).
  3. Boehringer Ingelheim Pty Limited. Dabigatran etexilate (Pradaxa) consumer medicine information (accessed 25 October 2020).
  4. Brieger D. Anticoagulation: a GP primer on the new oral anticoagulants. Aust Fam Physician 2014;43:254-9.
  5. Clinical Excellence Commission. Non-vitamin K antagonist oral anticoagulant (NOAC) guidelines. Sydney, Australia: 2017 (accessed 25 October 2020).
  6. Kirchhof P, Benussi S, Kotecha D, et al. 2016 ESC Guidelines for the management of atrial fibrillation developed in collaboration with EACTS: The Task Force for the management of atrial fibrillation of the European Society of Cardiology (ESC). Developed with the special contribution of the European Heart Rhythm Association (EHRA) of the ESC. Endorsed by the European Stroke Organisation (ESO). Eur Heart J 2016.;37:2893-2962.
  7. Stroke Foundation. Clinical Guidelines for Stroke Management 2017. Melbourne, Australia: Stroke Foundation, 2017 (accessed 25 October 2020).
  8. Queensland Government. Queensland Health. Guidelines for warfarin management in the community. Brisbane, QLD: The State of Queensland (Queensland Health), 2016 (accessed 25 October 2020).
  9. Australian Medicines Handbook. Blood and electrolytes. Adelaide: Australian Medicines Handbook Pty Ltd, 2017.
  10. Aspen Pharma Pty Ltd. Warfarin (Coumadin) product information. 2017 (accessed 25 October 2020).
  11. Cardiovascular Expert Group. Therapeutic Guidelines: Anticoagulant therapy. West Melbourne: Therapeutic Guidelines Pty Ltd, 2018 (accessed 25 October 2020).