Blood Thinners and Antiplatelet Medicines

Name: Blood Thinners and Antiplatelet Medicines
Creator: Dr Zamiel Hussain

Blood thinners and antiplatelet medicines are used to reduce the risk of blood clots. These medicines are commonly prescribed in primary care for conditions such as atrial fibrillation, previous stroke, heart attack, or after certain cardiac procedures.

Although they are often described as “blood thinners,” these medicines do not actually thin the blood. They reduce the blood’s ability to clot, which lowers the risk of harmful clots forming in arteries or veins.

This page explains how these medicines work, when they are used, and what monitoring is required.

These articles are intended as educational sources, not diagnostic nor taking place of a proper medical assessment. If you need help, please book an appointment with one of our GP’s.

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Why clot prevention matters

Blood clots can block arteries or veins and lead to serious complications, including:

stroke
heart attack
pulmonary embolism
deep vein thrombosis

In some conditions, the risk of clot formation is higher. In these cases, reducing clot risk may significantly lower the chance of serious events.

Treatment decisions are based on individual risk assessment rather than routine prescribing.

Anticoagulants (Commonly Called Blood Thinners)

Anticoagulants reduce the blood’s ability to form clots by interfering with clotting proteins.

Direct Oral Anticoagulants (DOACs)

DOACs are widely used in primary care for conditions such as atrial fibrillation and venous thromboembolism.

Common examples include:

apixaban
rivaroxaban
edoxaban
dabigatran

They are often preferred because they:

have predictable effects
do not usually require routine clotting blood tests
have fewer dietary restrictions compared with older treatments

Monitoring still includes kidney function checks and clinical review.

Warfarin

Warfarin is an older anticoagulant that works by affecting vitamin K–dependent clotting factors.

It requires:

regular blood testing (INR monitoring)
careful dose adjustment
awareness of dietary vitamin K intake
review of drug interactions

Warfarin remains appropriate in certain situations, particularly where DOACs are not suitable.

Antiplatelet Medicines

Antiplatelet medicines reduce the ability of platelets to stick together, lowering clot risk within arteries.

They are commonly used after:

heart attack
stroke
certain cardiac procedures
established vascular disease

Common examples include:

aspirin
clopidogrel
ticagrelor

Unlike anticoagulants, antiplatelets mainly reduce arterial clot risk rather than venous clot formation.

Bleeding Risk and Safety

All blood thinners increase bleeding risk. This may include:

easy bruising
nosebleeds
prolonged bleeding from cuts
heavier menstrual bleeding

More serious bleeding can occur and requires urgent medical attention.

Prescribing decisions always balance clot prevention benefit against bleeding risk.

Red flags: serious bleeding on blood thinners

Seek urgent help if any of the following occur while taking anticoagulants or antiplatelet medicines.

Bleeding that will not stop Heavy bleeding from a cut or wound that does not settle with pressure.

Black stools or vomiting blood Black, tarry stools, vomiting blood, or vomit that looks like coffee grounds.

Head injury or severe headache Any head injury, collapse, confusion, or a severe or worsening headache.

Stroke-like symptoms Sudden weakness, facial droop, speech difficulty, or new vision problems.

Blood in urine or coughing blood Visible blood in urine, coughing up blood, or large unexplained bruises.

Unexpected heavy bleeding Heavy vaginal bleeding outside your normal pattern, or bleeding with dizziness or fainting.

What to do: If you think you have serious bleeding or possible stroke symptoms, call 999 immediately. If you have had a fall or head injury while on blood thinners, urgent assessment is advised even if you feel well.

Monitoring and Long-Term Review

Blood thinners require structured review. This may include:

kidney function blood tests (for DOACs)
INR testing (for warfarin)
review of bleeding symptoms
assessment of other medications

Medication interactions are particularly important with anticoagulants.

You can read more in:

Surgery, Dental Work, and Procedures

Patients taking blood thinners should inform healthcare professionals before:

surgery
dental procedures
invasive investigations

In some cases, medication adjustments may be required before procedures.

Blood Thinners in Remote GP Care

Medication reviews and risk assessments can often be conducted remotely. However, abnormal bleeding, falls, head injury, or sudden neurological symptoms require urgent in-person assessment.

Frequently Asked Questions

1. What is the difference between anticoagulants and antiplatelet medicines?

Anticoagulants reduce clotting protein activity and are commonly used for atrial fibrillation or venous clots. Antiplatelet medicines reduce platelet stickiness and are often used after heart attack or stroke.

2. Do blood thinners require regular blood tests?

Some do. Warfarin requires regular INR monitoring. DOACs usually do not require routine clotting tests but still need periodic kidney function checks.

3. What should I do if I miss a dose of a blood thinner?

Advice depends on the specific medication. If a dose is missed, follow the patient information leaflet guidance and contact a GP if unsure. Do not double dose unless specifically advised.