What medications, such as birth control pills (containing estrogen), can cause thrombosis (blood clots) if taken in excess?

From the Guidelines

Birth control pills containing estrogen, such as Yaz, Yasmin, or Ortho Tri-Cyclen, can cause blood clots if taken in excess, particularly those with higher estrogen content. The risk of thrombosis is dose-dependent, with higher doses or concentrations creating greater risk 1. Other medications that can increase clotting risk include hormone replacement therapy (HRT) containing estrogen, selective estrogen receptor modulators like tamoxifen and raloxifene, and certain cancer treatments such as thalidomide, lenalidomide, and bevacizumab. Some antipsychotic medications (clozapine, olanzapine), erythropoiesis-stimulating agents, and corticosteroids can also increase thrombosis risk.

Key points to consider:

• The risk of blood clots is higher in individuals with additional risk factors such as smoking, obesity, advanced age, personal or family history of clots, or certain genetic conditions 1.
• The baseline incidence of venous thromboembolism in adolescents is up to 1 per 10,000 woman-years, and currently available COCs increase the risk of blood clot three to fourfold, or up to 4 per 10,000 woman-years 1.
• Progestin-only methods are widely accepted as a lower-risk option in patients for whom estrogens are contraindicated but who still need effective contraception 1.
• People taking these medications should discuss their individual risk with their healthcare provider and be particularly cautious when taking these medications.

It is essential to weigh the benefits and risks of contraceptive methods against unwanted pregnancy and to consider the individual's anatomy and physiology when determining the best contraceptive option 1.

From the FDA Drug Label

The risk of thromboembolic and thrombotic disease associated with the use of oral contraceptives is well established Case control studies have found the relative risk of users compared to non-users to be 3 for the first episode of superficial venous thromboembolic disease, 4 to 11 for deep vein thrombosis or pulmonary embolism, and 1. 5 to 6 for women with predisposing conditions for venous thromboembolic disease Several epidemiologic studies indicate that third generation oral contraceptives, including those containing desogestrel, are associated with a higher risk of venous thromboembolism than certain second generation oral contraceptives

Medications that could cause blood clots if taken in excess include:

• Oral contraceptives, particularly those containing estrogen and progestogen, such as ethinyl estradiol 2, 2, 2 Key points:
• The risk of thromboembolic disease associated with oral contraceptives is not related to length of use and disappears after pill use is stopped
• Women with predisposing conditions, such as hypertension, hyperlipidemias, obesity, and diabetes, are at a higher risk of thromboembolic disease
• Oral contraceptives should be used with caution in women with cardiovascular disease risk factors

From the Research

Medications that Can Cause Blood Clots

Medications such as birth control pills, particularly those containing estrogen, can increase the risk of thrombosis (blood clots) if taken in excess.

• Estrogen-containing oral contraceptives have been shown to increase the risk of venous thrombosis, myocardial infarction, and stroke 3.
• The risk of thrombosis is higher during the first year of use, with the use of desogestrel- or gestodene-containing oral contraceptives, and among women with a prothrombotic predisposition 3.
• Progestin-only contraceptives (POCs) may also increase the risk of venous thromboembolism (VTE), particularly among women with certain medical conditions or thrombogenic mutations 4.

Specific Medications and Their Risks

• Combined oral contraceptives (COCs) containing ethinylestradiol (EE) and a synthetic progestin have a higher risk of VTE compared to older COCs with norethisterone or levonorgestrel 5.
• Newer COCs with desogestrel, drospirenone, or gestodene have a higher risk of VTE compared to older COCs 5.
• Progestin-only hormonal contraception, such as depot medroxyprogesterone acetate, may increase the risk of VTE 4, 5.
• Oral contraceptives containing 17β-estradiol and nomegestrol acetate may have a lower risk of VTE compared to other combined oral contraceptives 6.

Factors that Increase the Risk of Blood Clots

• High levels of clotting factors, such as factor VII, may increase the risk of thrombosis 7.
• Estrogen dose and the level of factor VII are strongly related, suggesting that high levels of estrogen may increase the risk of thrombosis 7.
• Women with a history of VTE, thrombophilia, or certain medical conditions may be at higher risk of blood clots when taking hormonal contraceptives 4, 5.