Navigating Bleeding Risks: When Not to Give Anticoagulants?

October 12, 2025 •

3 min read

Anticoagulants are among the drugs most frequently associated with hospital admission due to adverse drug reactions. Understanding when not to give anticoagulants is critical for patient safety, balancing the prevention of blood clots against the risk of severe bleeding.

Quick Summary

Clinicians must weigh the risk of thrombosis against the danger of hemorrhage when prescribing anticoagulants. This involves identifying absolute contraindications, such as active bleeding, and relative ones where the medication may be used with caution.

Key Points

Absolute Contraindications: Active bleeding, recent intracranial hemorrhage, and major trauma are absolute reasons to avoid anticoagulants.
Relative Contraindications: Conditions like chronic liver disease, high fall risk, or a history of GI bleeding require a careful risk-benefit analysis.
Patient-Specific Factors: Kidney and liver function are critical, as they affect the metabolism and clearance of anticoagulants, especially DOACs.
Drug-Specific Rules: DOACs are contraindicated in patients with mechanical heart valves, a scenario where warfarin remains the standard of care.
Perioperative Planning: Anticoagulants must be temporarily stopped before most surgeries, with the timing dependent on the specific drug and the procedure's bleeding risk.
Risk Scores are a Guide: A high bleeding risk score should prompt mitigation of risk factors, not automatic withholding of therapy.
Elderly Population: Advanced age increases bleeding risk, but the benefits of stroke prevention often outweigh this risk, even in patients with falls.

The Critical Balance: Thrombosis vs. Hemorrhage

Anticoagulant therapy is a cornerstone in the prevention and treatment of thromboembolic events like atrial fibrillation (AF) and venous thromboembolism (VTE). However, their primary benefit—inhibiting clot formation—is also their greatest risk: bleeding. The decision to initiate or withhold these medications hinges on a careful, individualized assessment of a patient's risk for clotting versus their risk for a dangerous bleed. This underscores the necessity for clinicians to have a robust understanding of situations where the risks of anticoagulation outweigh the benefits.

Absolute Contraindications: When Anticoagulants Are Strictly Avoided

An absolute contraindication means the potential for harm is so significant that a procedure or medicine must be avoided. In the context of anticoagulation, these are situations where the risk of life-threatening bleeding is unacceptably high.

Key absolute contraindications include:

Active, Uncontrolled Bleeding: This is the most straightforward contraindication.
Recent Intracranial Hemorrhage (ICH): A history of ICH is a frequent reason for deeming a patient ineligible for anticoagulation, as the risk of recurrence can be catastrophic. Anticoagulation should not be restarted in patients with cerebral amyloid angiopathy due to the high risk of recurrent ICH.
Major Trauma or Recent Major Surgery: Especially involving the brain, spine, or eyes.
Severe Coagulopathy: Pre-existing conditions that impair the body's ability to form clots.
Certain Neurological Procedures: Procedures like a lumbar puncture or the placement of an epidural or spinal anesthesia require that anticoagulants be held for a specific period to prevent spinal hematoma.

Relative Contraindications: A Case-by-Case Assessment

Relative contraindications are more common and require careful clinical judgment, weighing the benefits against the risks. In these cases, treatment may proceed if the benefit is deemed to outweigh the potential harm, often with increased monitoring or modification of other risk factors.

Common relative contraindications include:

History of Significant Bleeding: A past gastrointestinal or genitourinary bleed may increase the risk of a future event. However, once the source is identified and treated, anticoagulation may be possible.
Severe Liver Disease: All Direct Oral Anticoagulants (DOACs) are contraindicated in severe hepatic disease (Child-Pugh Class C), where warfarin may be the only option. For mild to moderate liver disease, some DOACs can be used with caution.
Thrombocytopenia (Low Platelet Count): Increases bleeding risk, and the decision to anticoagulate depends on severity and indication.
High Risk of Falls or Frailty: While a concern, guidelines state that fall risk alone should not be a reason to withhold anticoagulation, as stroke prevention often outweighs the risk.
Uncontrolled Hypertension: Increases the risk of bleeding, particularly intracranial hemorrhage, and blood pressure should be controlled before therapy.
Pregnancy: Warfarin and DOACs are generally not recommended. Low-molecular-weight heparin is often preferred.
Concurrent Use of Other Medications: NSAIDs or antiplatelet agents significantly increase bleeding risk and should be avoided if possible.

Comparison of Contraindications: Warfarin vs. DOACs

The choice between warfarin and DOACs can be influenced by specific patient conditions.


Condition	Warfarin	DOACs (Direct Oral Anticoagulants)
Mechanical Heart Valves	Preferred Agent	Contraindicated
Moderate-to-Severe Mitral Stenosis	Preferred Agent	Contraindicated
Antiphospholipid Syndrome	Often Preferred	Use with caution; evidence evolving.
Severe Renal Impairment	Can be used with monitoring.	Dosing must be adjusted; may be contraindicated in end-stage renal disease.
Severe Liver Disease (Child-Pugh C)	Can be used with extreme caution and monitoring.	Contraindicated.
High GI Bleeding Risk	Higher risk compared to some DOACs like apixaban.	May be preferred, but risk varies by agent. Standard-dose DOACs may have a higher GI bleed risk than warfarin.

Perioperative Management: When to Temporarily Stop

For planned surgery, the timing of stopping and restarting anticoagulants depends on the drug's half-life, renal function, and the procedure's bleeding risk. Warfarin is typically stopped about 5 days before, while DOACs are often held for 1-4 days. Bridging with heparin is generally not needed for patients on DOACs but may be considered for high-risk patients on warfarin.

Conclusion

The decision of when not to give anticoagulants is a complex clinical judgment balancing the risk of clots against serious bleeding. While absolute contraindications like active bleeding or recent intracranial hemorrhage exist, most scenarios involve relative contraindications requiring a nuanced evaluation. Factors like organ function, concomitant medications, and comorbidities dictate whether to anticoagulate and the choice of agent. A high bleeding risk score should prompt mitigation of risk factors, not automatic withholding of therapy.

For more information, a helpful resource is the National Institutes of Health's StatPearls article on Anticoagulation: https://www.ncbi.nlm.nih.gov/books/NBK560651/

Frequently Asked Questions

An absolute contraindication is a situation where a medication must be avoided because it could cause a life-threatening situation. For anticoagulants, this includes active, uncontrolled bleeding, recent major surgery, and acute intracranial hemorrhage.

It depends on the severity. While historically avoided, it's now known patients with cirrhosis are at risk for both bleeding and clotting. All DOACs are contraindicated in severe (Child-Pugh C) liver disease, but some may be used with caution in mild-to-moderate cases. Warfarin can be used but requires very careful monitoring.

Yes, in many cases. Major guidelines state that a high risk of falls is not, by itself, a reason to withhold anticoagulation, as the benefit of preventing a stroke often outweighs the risk of bleeding from a fall.

Not for everyone. While DOACs are associated with a lower risk of intracranial hemorrhage, warfarin is the preferred or required anticoagulant for patients with mechanical heart valves or moderate-to-severe mitral stenosis.

This depends on the specific medication and surgery. Warfarin is typically stopped 5 days before, while DOACs (like apixaban or rivaroxaban) are often stopped 1-3 days prior due to their shorter half-lives. Always follow the specific instructions from your clinical team.

No, it is generally not recommended. The concurrent use of NSAIDs with anticoagulants significantly increases the risk of bleeding, especially in the gastrointestinal tract, and should be avoided if possible.

Patients on DOACs undergoing emergency surgery have an increased risk of major bleeding. Reversal agents exist to counteract the anticoagulant effect. Idarucizumab reverses dabigatran, and andexanet alfa reverses factor Xa inhibitors like apixaban and rivaroxaban.