What are the side effects of Marvelon?

When taking Marvelon, please monitor for a rare but serious side effect of blood clots: shortness of breath, chest pain (particularly with deep breathing), coughing up blood, persistent leg pain, or redness, swelling, or warmth in your lower legs (usually one-sided) can all be indications of a blood clot in the legs or lungs, and should never be ignored. 

Please seek medical attention promptly if this occurs, in the emergency department.