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.
