There are preliminary results that a FDA-funded study of Yaz and similar drospirenone-based contraceptives show they carry a 1.5-fold increase in the risk of blood clots compared to older hormonal contraceptives. That study follows six others, four of which have shown an increased clot risk for Yaz and its ilk.
The DrugCite database of adverse event information culled from the FDA shows that blood-clot events are more common for pills containing drosperinone than for levonorgestrel, an older version of the progestin ingredient in contraceptive pills:
- Most Common Drospirenone Adverse Events
- Pulmonary Embolism: 119
- Deep Vein Thrombosis: 99
- Gallbladder Injury: 57
- Thrombosis: 20
- Most Common Levonorgestrel Adverse Events
- Pulmonary Embolism: 17
- Deep Vein Thrombosis: 10
- Thrombosis: 9
- Gallbladder Injury: 0
