Typically the lips are pinkish in colour, but it can happen that a person's lips turn a bluish or brownish shade or become extremely pale. If this happens infrequently and only for a short time, then there is usually no cause for concern. However, this is not the case if the change in colour of the lips persists over a long period of time, as it may be linked to cyanosis, an iron deficiency anaemia or an allergy, or it may be a side effect of the patient's use of certain pharmaceuticals.