Birth control pills are a used and effective method of contraception. While generally considered safe, some types carry a rare but serious risk of blood clots. Understanding this risk helps individuals make informed decisions about their contraceptive choices.
Understanding Blood Clot Risk
Deep vein thrombosis (DVT) is a blood clot that forms in a deep vein, typically in the leg. If a piece of this clot breaks off and travels to the lungs, it can cause a pulmonary embolism (PE), a potentially life-threatening condition. The medical term encompassing both DVT and PE is venous thromboembolism (VTE).
Combined hormonal contraceptives, which contain both estrogen and progestin, can increase the risk of VTE. This occurs because estrogen influences the body’s clotting factors. In contrast, progestin-only pills generally do not significantly increase the risk of VTE.
Pill Formulations and Their Risk Profiles
Combined oral contraceptives (COCs) contain both estrogen and progestin, and both the dose of estrogen and the type of progestin can influence VTE risk. Higher doses of estrogen are generally associated with a greater risk of blood clots. Modern COCs typically use lower doses of ethinyl estradiol. However, even with these lower doses, a risk of VTE remains.
The type of progestin in COCs also contributes to the risk profile. Pills containing levonorgestrel, a second-generation progestin, are generally associated with a lower risk of VTE. In comparison, third-generation progestins like desogestrel and gestodene, and the fourth-generation progestin drospirenone, have been linked to a higher VTE risk than levonorgestrel. Despite these differences, the overall absolute increase in risk from newer progestins is still considered small when compared to the general VTE risk associated with COCs.
Progestin-only pills (POPs) do not contain estrogen. These formulations are generally not associated with a significantly increased risk of VTE when compared to individuals not using hormonal contraception. This characteristic often makes POPs a preferred option for individuals who have specific risk factors that make estrogen-containing contraceptives unsuitable.
Individual Risk Factors
An individual’s personal health profile significantly influences their overall risk of blood clots when using birth control pills. Age increases VTE risk, particularly for individuals over 35. Smoking also elevates this risk, especially in women over 35. Obesity contributes to an increased likelihood of blood clot formation.
A personal or family history of blood clots can also predispose an individual to a higher risk. Individuals with migraines that include aura face an increased risk for blood clots, particularly if they use combined hormonal contraceptives. Genetic clotting disorders and prolonged immobilization also heighten VTE risk. Discussing these individual risk factors with a healthcare provider is important to determine the most suitable and safest birth control option.
Recognizing Blood Clot Symptoms
Awareness of blood clot symptoms is important for prompt medical attention. Symptoms of deep vein thrombosis (DVT), typically in a leg, include swelling, pain, or tenderness in the affected limb. The skin around the painful area may also appear reddish or discolored and feel warm to the touch. These symptoms might sometimes feel similar to a muscle cramp or soreness, but they tend to persist and worsen.
A pulmonary embolism (PE) presents with distinct symptoms when a blood clot travels to the lungs. These include sudden shortness of breath, chest pain that may worsen with deep breathing or coughing, and a rapid heart rate. An unexplained cough, sometimes producing bloody mucus, or feelings of dizziness and lightheadedness can also indicate a PE. Seek immediate medical attention if any of these symptoms occur.