What Are Blood Thinners?

Blood thinners are medications that help prevent blood clots from forming within the circulatory system. When a clot forms in a vein or artery, it can travel to vital organs such as the heart, brain, or lungs, potentially causing a heart attack, stroke, or pulmonary embolism. Individuals with irregular heart rhythms (like atrial fibrillation), congenital heart defects, coronary stents, or heart valve surgery are at increased risk of developing blood clots.

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How Does Blood Clotting Work?

Blood clotting is a natural and necessary response to injury. Platelets, red blood cells, white blood cells, and fibrin combine at the injury site to form clots that stop bleeding. However, some people have a tendency to form unnecessary clots and need blood thinners to reduce the risk of harmful clot formation.

Types of Blood Thinners

Blood thinners fall into two main categories, each affecting the clotting process differently. They can prevent clots from forming but cannot dissolve existing clots.

Antiplatelet Drugs

These medications prevent platelets from sticking together to form clots. They are usually taken orally. Common antiplatelet drugs include aspirin and various prescription medications. These drugs generally have few food or drug interactions but may not be suitable for people with asthma, high blood pressure, liver or kidney disease, or ulcers.

Anticoagulant Drugs

Anticoagulants interfere with the chemical processes that cause blood clotting, increasing the time it takes for clots to form. Examples include heparin and warfarin; heparin is often started intravenously. Anticoagulants are a stronger treatment than antiplatelet drugs and are typically prescribed for people at high risk of stroke or those with atrial fibrillation. Newer anticoagulants approved by the FDA include apixaban, dabigatran, and rivaroxaban.

Patients on blood thinners usually undergo monthly blood tests to measure how quickly their blood clots, allowing doctors to adjust dosages as needed.

Risks and Precautions of Blood Thinners

The primary risk of blood thinners is bleeding. Patients should always consult their physician before taking any other medications, including over-the-counter drugs. Aspirin, in particular, can increase the blood-thinning effect and raise the risk of excessive bleeding.

Other medications to be cautious about include:

  • Nonsteroidal anti-inflammatory drugs (NSAIDs)
  • Certain cold or stomach medications
  • Some herbal supplements and vitamins, especially vitamin K

Patients on blood thinners are also at risk for internal bleeding. They should contact their doctor immediately if they experience a significant fall or injury.