Understanding Lo Loestrin Fe and Blood Clot Risk
Lo Loestrin Fe is a combined oral contraceptive containing norethindrone acetate and ethinyl estradiol, notable for having the lowest daily estrogen dose at 10 mcg. Despite the low dose, all combined hormonal contraceptives (CHCs) increase the risk of serious cardiovascular events, including blood clots, stroke, and heart attack.
The FDA Black Box Warning
The FDA requires a boxed warning for Lo Loestrin Fe, the most serious type of warning, emphasizing the increased risk of serious cardiovascular events in women who smoke while using hormonal birth control, particularly those over 35. Doctors typically will not prescribe CHCs to this group due to the significantly amplified danger.
How Estrogen Influences Clotting
The estrogen component, ethinyl estradiol, increases clotting factors in the blood, raising the risk of clots. These clots can lead to deep vein thrombosis (DVT) or pulmonary embolism (PE), which can be life-threatening. The VTE risk for COC users is 3 to 9 per 10,000 women per year, higher than non-users but lower than during pregnancy and postpartum. The risk is highest in the first year of use.
Lo Loestrin Fe's Ultra-Low-Dose Formulation
Lo Loestrin Fe's 10 mcg ethinyl estradiol dose is lower than other low-dose pills (20 or 30 mcg). Lower estrogen doses are associated with a reduced VTE risk, with a decrease from 30-40 mcg to 20 mcg potentially lowering risk by 18%. While the 10 mcg dose may offer a lower risk than higher doses, the risk is still elevated compared to not using CHCs.
Individual Risk Factors are Key
Several personal factors increase the risk of blood clots with Lo Loestrin Fe. It is contraindicated for those with a history of blood clots, stroke, heart attack, certain heart issues, or inherited clotting disorders.
Other risk factors include:
- Age: Risk increases with age.
- Obesity: BMI of 35 or more is a contraindication.
- Smoking: Dramatically increases cardiovascular risks.
- High Blood Pressure: Uncontrolled hypertension is a contraindication.
- Diabetes: With blood vessel complications, it's a contraindication.
- Migraines with Aura: Increases stroke risk and is a contraindication.
- Major Surgery or Prolonged Immobility: Lo Loestrin Fe should typically be stopped before and after major surgery.
- Family History: Can indicate a predisposition to clotting.
Comparison of Blood Clot Risk
| Group | Estrogen Exposure | Estimated VTE Risk (per 10,000 women per year) |
|---|---|---|
| Non-Pregnant, Non-Users | None | 1.9 to 3.7 |
| Users of Combined Oral Contraceptives | Varies (10-50 mcg) | 3 to 9 |
| Users of Drospirenone-containing Pills | ~30 mcg | ~10 |
| During Pregnancy and Postpartum | High (natural) | Significantly higher than COC users |
Recognizing the Symptoms
Recognize symptoms of a blood clot and seek immediate medical attention if experienced:
- DVT (Legs/Arms): Pain, swelling, warmth, tenderness, or discoloration.
- PE (Lungs): Sudden shortness of breath, sharp chest pain, rapid heartbeat, or coughing up blood.
- Stroke (Brain): Sudden severe headache, trouble speaking, vision changes, or weakness/numbness on one side.
- Heart Attack (Heart): Chest pain, upper body pain, shortness of breath, sweating, or nausea.
Conclusion
Lo Loestrin Fe, like other combined hormonal contraceptives, increases the risk of blood clots. While its 10 mcg estrogen dose is the lowest available and may offer a reduced risk compared to higher-dose pills, the risk is still elevated over non-use. Individual health, especially smoking, age, and a history of clotting issues, are crucial factors. Consult a healthcare provider to discuss risks and benefits and determine if Lo Loestrin Fe is suitable for you.
For more information, consult the official patient information provided by the manufacturer. https://www.rxabbvie.com/pdf/lo-loestrin-fe_pi.pdf
