These conditions may be to blame for purple lips: Lack of oxygen (that could be the result of a PFO as blood from the rightside (some blood doesn't go to the lungs but is shunted to the leftside and pumped into circulation), poor circulation, cold temperatures and cyanosis
Cyanosis is a medical condition that causes discoloration and bluing of the skin and membranes. Linked to lack of oxygen, cyanosis may be attributed to underlying lung or breathing problems. Often seen in infants with birth defects or lung problems, cyanosis also affects the elderly.The first physical symptom of cyanosis is a bluish cast on the fingernails, lips, capillaries, veins and tongue. Cyanosis, in many cases, is linked to a serious underlying disease.
"The following serious diseases or conditions may be causing cyanosis, or bluing of the lips:
•Heat disease
•Heart failure
•Lung disease
•Myocardial infarction
•Pulmonary embolism
•Chronic bronchitis
•Asthma
•Abnormal hemoglobin levels
•Heart valve disease
•Hypoventilation".
The possibilities are quite extensive for lips turning blue, and you can do a differential dx by eliminating that what you know cannot be a condition for you.
Hope this helps, and if you have any further questions or comments you are welcome to respond. take care,
Ken