Blue lips are sometimes associated with extreme cold and can be worrying.The NHS says that cyanosis, which is when your lips turn blue or grey because you’re not getting enough oxygen, is potentially serious.It can be a sign of something like heart failure or pneumonia. Health information site Healthline says that blue lips can sometimes be a sign of sickle cell anaemia too.Other causes include being in cold air, wearing jewellery that’s too tight, certain medications, vigorous exercise (I’d always get blue lips after a long run) and asthma.How can I tell if my blue lips are safe or not?Healthline says that you can tell blue lips caused by cold versus blue lips caused by oxygen deprivation by massaging them. “If normal colour returns with warming or massage, your lips aren’t getting enough blood supply,”