Antithrombotic therapy aims to prevent blood clots and the serious damage they can cause. Types include anticoagulants like heparin, antiplatelets like aspirin, and emergency thrombolytics.

Thrombosis is when a blood clot forms in a blood vessel like a vein or an artery. When the clot blocks blood flow to your cells and organs, it can cause problems. Large clots and clots that develop in the wrong place can be dangerous.

Doctors can use antithrombotic therapy to help keep clots from forming. They can also use it to dissolve a clot that’s already formed.

Here’s what to know about antithrombotic therapy, including the types of medications doctors can prescribe.

Why worry about blood clots?

You may have heard of a condition related to blood clots called deep vein thrombosis (DVT). DVT means the clot is in a deep vein, usually in your pelvis, thigh, or lower leg, but sometimes in your arm. These clots can break off and travel to your lungs in a life threatening complication called pulmonary embolism.

When a blood clot forms in an artery, it’s called arterial thrombosis. This kind of blood clot can cause a heart attack or stroke.

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Antithrombotic therapy uses drugs to reduce the chance of blood clotting in your veins or arteries. Doctors can prescribe these medications if they think you may be at risk of a heart attack, a stroke, or another health complication due to a clot.

There are three major types of medications doctors can prescribe to treat thrombosis. They may prescribe one or a combination. These medications can:

  • delay clotting
  • keep the platelets in your blood from clotting
  • dissolve a dangerous clot that’s already formed

Three types of drugs prevent or reduce the likelihood of thrombosis. These are:

Each type works differently.


Blood clots all have the same components: white blood cells, platelets, red blood cells, and fibrin. Fibrin is a blood protein that your body uses to help heal wounds and rebuild healthy tissue.

Anticoagulants and antiplatelets keep these components from sticking together to cause a clot. Both are also called blood thinners, but they work differently.

Anticoagulants slow down the processes your body goes through to make clots. They make it harder for your body to form clots and help prevent existing clots from getting bigger. They don’t break up clots that have already formed.


Antiplatelets also prevent clots from forming, but they work differently than anticoagulants. They work directly on the platelets.

Platelets are special cells that travel to the site of an injury and stick together to form a clot and prevent excess bleeding. Antiplatelets keep them from fusing.

Thrombolytics (fibrinolytics)

Unlike anticoagulants and antiplatelets, which work to prevent clots from forming in the first place, thrombolytics break up clots that have already formed.

They work by activating a protein in your liver, creating an enzyme that can quickly dissolve the fibrin in a clot.

Doctors use thrombolytics when the clot is dangerous and has caused severe health problems like a stroke, a heart attack, or DVT. They aren’t for everyday use, like the other types of medications. Instead, doctors reserve them for emergencies.

Examples of anticoagulants include:

Examples of antiplatelet medications include:

  • aspirin
  • dipyridamole (Persantine)
  • ticlopidine (Ticid)
  • clopidogrel (Plavix)
  • prasugrel (Effient)
  • ticagrelor (Brilinta)
  • cangrelor (Kenreal)
  • vorapaxar (Zontivity)
  • abciximab (ReoPro)
  • eptifibatide (Integrilin)

Your doctor may prescribe one medication, medication plus aspirin, or a combination of medications to prevent or treat blood clots.

For example, someone who’s had a heart attack or stroke may choose dual antiplatelet therapy. That means taking a prescription antiplatelet medication along with aspirin. Doctors may recommend that they take the prescribed antiplatelet for months or years and take aspirin for the rest of their life.

Intravenous thrombolytics that doctors may use in an emergency include:

  • alteplase (Activase)
  • reteplase (Retavase)
  • tenecteplase (TNKase)
  • anistreplase (Eminase)
  • streptokinase (Streptase)
  • urokinase (Kinlytic)

Like all medications, antithrombotic therapy medications can cause side effects.

The side effects vary by medication, but they generally include:

  • an increased risk of bleeding
  • an upset stomach
  • nausea
  • diarrhea

Is antithrombotic therapy safe for older adults?

Older people may benefit from antithrombotic therapy, but they may have a higher likelihood of bleeding than younger people. They also may have other comorbid conditions that doctors must consider when creating a treatment plan.

While daily aspirin can help some people at risk of thrombosis, it may harm others.

In 2022, the European Society of Cardiology Working Group on Thrombosis found that for people over 70 years old, a daily dose of aspirin might carry more risk than benefit in some cases.

It’s important to discuss your complete health history and current conditions with your healthcare team before starting any new medications. Make sure you understand the risks and benefits of each drug.

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Here are answers to some questions you may have about antithrombotic therapy.

Is aspirin antithrombotic therapy?

Aspirin is an antiplatelet drug that blocks the activation of platelets. People commonly use it to reduce their risk of heart attack, stroke, or peripheral vascular disease.

What’s the difference between antithrombotics and anticoagulants?

Anticoagulants are a type of antithrombotic medication. They keep your blood from creating a clot or making an existing clot bigger. That’s different from thrombolytics, which break up or dissolve clots that have already formed.

Can you take anticoagulants and antiplatelets together?

You can take anticoagulants and antiplatelets together. Your doctor may suggest that you do, depending on your situation.

Antithrombotic therapy uses medications to prevent your body from producing blood clots. In some cases, these medications can break up a dangerous blood clot that’s already caused a severe problem, like a stroke or heart attack.

Antithrombotic therapy comprises three medication types: anticoagulants, antiplatelets, and thrombolytics. Depending on your situation, your doctor may prescribe one or more of them.