1 month after my 30th birthday I was hospitalized for a week for developing blood clots that went to my lungs (followed by 3 months of wicked home treatment). They told me it was because I was smoking cigarettes while on birth control... and this was a common occurrence. At any age. I always thought there wasn't a great risk of health problems because of that combo until 35... but the truth is the risk only goes UP, drastically... But the risk is still great at any age. If you smoke, please make sure your doctor knows, and ask about the benefits of being on progesterone only birth control (if you can't quit). It could save your life.