Some consider habitual lip licking or picking to be a form of nervous tic, and do not consider this to be true angular cheilitis, instead calling it perlèche (derived from the French word pourlècher meaning "to lick ones lips"), or "factitious cheilitis" is applied to this habit. The term "cheilocandidiasis" describes exfoliative (flaking) lesions of the lips and the skin around the lips, and is caused by a superficial candidal infection due to chronic lip licking. Less severe cases occur during cold, dry weather, and is a form of chapped lips. Individuals may lick their lips in an attempt to provide a temporary moment of relief, only serving to worsen the condition.The sunscreen in some types of lip balm degrades over time into an irritant. Using expired lipbalm can initiate mild angular cheilitis, and when the person applies more lipbalm to alleviate the cracking, it only aggravates it. Because of the delayed onset of contact dermatitis and the recovery period lasting days to weeks, people typically do not make the connection between the causative agent and the symptoms. Nutritional deficiencies
Several different nutritional deficiency states of vitamins or minerals have been linked to AC. It is thought that in about 25% of people with AC, iron deficiency or deficiency of B vitamins are involved. Nutritional deficiencies may be a more common cause of AC in Third World countries. Chronic iron deficiency may also cause koilonychia (spoon shaped deformity of the fingernails) and glossitis (inflammation of the tongue).
If there is a nutritional deficiency underlying the condition, various other signs and symptoms such as glossitis (swollen tongue) may be present. In people with angular cheilitis who wear dentures, often there may be erythematous mucosa underneath the denture (normally the upper denture), an appearance consistent with denture-related stomatitis. Typically the lesions give symptoms of soreness, pain, pruritus (itching) or burning or a raw feeling. Causes
Angular cheilitis is thought to be multifactorial disorder of infectious origin, with many local and systemic predisposing factors. The sores in angular cheilitis are often infected with fungi (yeasts), bacteria, or a combination thereof; this may represent a secondary, opportunistic infection by these pathogens. Some studies have linked the initial onset of angular cheilitis with nutritional deficiencies, especially of the B (B2-riboflavin) vitamin and iron (which causes iron deficiency anemia), which in turn may be evidence of malnutrition or malabsorption. Angular cheilitis can be a manifestation of contact dermatitis, which is considered in two groups; irritational and allergic. Infection
The involved organisms are:

Candida species alone (usually Candida albicans), which accounts for about 20% of cases,
Bacterial species, either:
Staphylococcus aureus alone, which accounts for about 20% of cases,
β-hemolytic streptococci alone. These types of bacteria have been detected in between 8–15% of cases of angular cheilitis, but less commonly are they present in isolation,
Or a combination of the above organisms, (a polymicrobial infection) with about 60% of cases involving both C. albicans and S. aureus.Candida can be detected in 93% of angular cheilitis lesions.