Some medicines can increase the risk of blood clots, heart attacks, or strokes in certain people. When a potential safety concern is identified, healthcare authorities may update prescribing information, restrict a medicine’s use, issue a warning, or occasionally remove a product from the market.
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This does not mean that every person taking one of these medicines will experience a serious complication. The level of risk depends on the specific medication, dose, duration of use, underlying health conditions, age, lifestyle, and other individual factors.
Patients should remain informed and discuss concerns with a doctor or pharmacist, particularly when using medicines known to affect blood clotting, blood pressure, circulation, or cardiovascular health.
What Is a Blood Clot?
Blood clotting is a normal process that helps stop bleeding after an injury. A thrombus is a blood clot that forms inside a blood vessel and remains there. When a clot develops without an appropriate reason or obstructs normal blood flow, it can become dangerous.
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A clot may partially or completely block a vein or artery. In some cases, part of it can break away and travel through the bloodstream to another organ. This traveling clot is called an embolus.
Possible Complications of Blood Clots
Deep vein thrombosis (DVT): A blood clot forms in a deep vein, most commonly in the leg. It may cause swelling, pain, warmth, or discoloration, although some people have few or no symptoms.
Pulmonary embolism (PE): A clot travels to the lungs and blocks blood flow. This can cause sudden shortness of breath, chest pain, rapid heartbeat, coughing, fainting, or coughing up blood.
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Ischemic stroke: Blood flow to part of the brain becomes blocked. Possible signs include facial drooping, weakness or numbness on one side of the body, speech difficulty, loss of balance, confusion, or a sudden change in vision.
Heart attack: Blood flow to part of the heart becomes blocked, frequently after a blood clot forms on a ruptured plaque inside a coronary artery. Symptoms may include chest pressure or discomfort that spreads to the arm, shoulder, jaw, neck, or back; shortness of breath; nausea; sweating; or unusual weakness.
These complications can be life-threatening and require immediate medical attention.
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Medicines That May Require Additional Caution
Medication risks must be evaluated individually. The following categories may be associated with an increased risk of blood clots or cardiovascular complications in certain circumstances:
Combined hormonal contraceptives: Birth-control pills, patches, and rings containing estrogen and a progestin can increase the risk of venous blood clots. The absolute risk remains low for many healthy users, but it may be higher in people with additional risk factors.
Menopausal hormone therapy: Some forms of estrogen-containing hormone therapy may increase the risk of blood clots and stroke, depending on the formulation, route of administration, dose, duration, age, and personal medical history.
Certain anti-inflammatory medicines: Some nonsteroidal anti-inflammatory drugs (NSAIDs) may increase the risk of heart attack or stroke, especially when used at higher doses, for prolonged periods, or by people with existing cardiovascular disease.
Some cancer treatments: Cancer itself can raise the risk of blood clots, and certain chemotherapy, hormonal, targeted, or immune-based treatments may further increase that risk.
Some medicines that stimulate red blood cell production: These medicines may increase the likelihood of cardiovascular or clotting complications in particular patients, especially when hemoglobin levels rise beyond the recommended target.
Certain antipsychotic medicines: Some studies have found an association between specific antipsychotics and an increased risk of venous blood clots, particularly in people with other risk factors.
Some appetite suppressants and weight-loss products: Certain prescription or unregulated products can affect heart rate, blood pressure, or cardiovascular health. Unapproved diet pills may contain undeclared or unsafe ingredients.
The presence of a warning does not automatically mean that a medicine is unsafe for everyone. For many patients, the expected benefit remains greater than the potential risk when the treatment is appropriately prescribed and monitored.
A Note About Vaccines and Blood Clots
A rare clotting disorder accompanied by low platelet levels was associated with certain adenovirus-vector COVID-19 vaccines. This reaction was uncommon and was different from ordinary deep vein thrombosis.
Having a risk factor does not mean that a clot will definitely occur. However, patients should tell their doctor about these factors before beginning a medicine that may affect clotting or cardiovascular health.
Warning Signs That Require Urgent Medical Attention
Seek emergency medical help immediately if you experience symptoms that could indicate a blood clot, pulmonary embolism, stroke, or heart attack.
Important warning signs include:
- Sudden shortness of breath or difficulty breathing
- Chest pain, pressure, tightness, or discomfort, particularly if it spreads to the arm, jaw, shoulder, back, or neck
- Coughing up blood
- Fainting, severe weakness, or a rapid heartbeat accompanied by breathing difficulty or chest pain
- New, unexplained swelling, pain, tenderness, warmth, or discoloration in one leg or arm
- Sudden weakness or numbness affecting the face, arm, or leg, especially on one side of the body
- Facial drooping, difficulty speaking, confusion, or trouble understanding speech
- Sudden loss of vision, blurred vision, severe dizziness, or loss of coordination
- A sudden, unusually severe headache, particularly when accompanied by neurological symptoms
Do not wait for these symptoms to disappear on their own. Call your local emergency service and follow its instructions. Do not drive yourself if you feel faint, confused, severely short of breath, or seriously unwell.
What Should You Do If You Are Concerned About a Medicine?
Do not stop a prescribed treatment suddenly unless an emergency professional or the prescriber instructs you to do so. Abruptly stopping certain medicines can cause withdrawal effects, allow the treated condition to worsen, or create additional health risks.
Contact your doctor or pharmacist and provide the exact name of the medicine, the dose, how long you have used it, and any symptoms you have noticed. Mention all prescription medicines, over-the-counter products, vitamins, herbal preparations, and supplements you take.
Ask whether your health history or other medications change the balance of benefits and risks. Your healthcare professional may recommend continuing the treatment, adjusting the dose, switching medicines, performing tests, or monitoring particular symptoms.
Never begin aspirin, anticoagulants, or other blood-thinning medicines on your own to prevent a suspected clot. These medicines can cause serious bleeding and should be used only when medically appropriate.
Check Reliable Safety Information
Medication warnings shared through social media are sometimes incomplete, outdated, or presented without the name, dose, or circumstances of the medicine involved.
For reliable information, consult the patient leaflet supplied with the medication, your doctor or pharmacist, and official notices from your national medicines regulator or public-health authority.
A recall in one country does not necessarily mean that every product with a similar name has been recalled worldwide. Recalls can apply to a specific manufacturer, batch, strength, formulation, or contamination problem rather than to the active ingredient itself.
Reporting Suspected Side Effects
If you experience an unexpected reaction, inform a healthcare professional. Suspected side effects can also be reported through the official pharmacovigilance system in your country.
A report does not prove that a medicine caused the event, but it helps regulators detect possible patterns and investigate new safety concerns. Include accurate information about the product, dose, dates of use, symptoms, medical history, and other medicines whenever possible.
Conclusion
Some medicines are associated with an increased risk of blood clots or cardiovascular complications, but the degree of risk differs considerably between products and individuals. A general warning should never replace an assessment of the exact medicine and the patient’s personal circumstances.
Learn the warning signs, discuss individual risk factors before starting treatment, and obtain information from qualified healthcare professionals and official authorities. Never discontinue an important prescription or take a blood thinner without medical guidance.
When symptoms suggest a pulmonary embolism, stroke, heart attack, or serious blood clot, immediate emergency care is essential. Recognizing the signs and acting quickly can save a life.
