ANGULAR CHEILIITIS:
A deficiency of B2, Riboflavin. Very common on a modern Western diet. Don’t be a vegetarian! Don’t drink any kind of soda, cola, fizzy pop drinks. Take 1 x B2 + 1x multi-B tablet for a week, (!00 to 200mg) Recommended dose i
s 1.5 to 2 mg, this is much too low for young people. 100mg once a week thereafter or 10mg daily.
Source: Experience, Merck’s manual, Upjohn’s vitamin manual, the Nurient bible by Henry Osiecki. Newton’s pharmacy.
NHMRC riboflavin recommendations for Australian adults:
1. – RDI men: 1.3 mg/day
– RDIwomen:1.1mg/day
 
“The most common signs are pallor and maceration of the mucosa in the angle of the mouth (angular stomatitis) and vermilion surfaces of the lips (cheilosis), followed by superficial linear fissures that may leave scars when healed. When these lesions are infected by Candida albicans, greyish white exuberant lesions (perleche) result. The tongue may appear magenta/ Cutaneous lesions usually affect the nasolabial folds, alae nasi, ears, eyelids, scrotum and labia majora. These areas become red, scaly and greasy and sebaceous material acccumulates in hair follicles producing dyssebacia or shark skin. Treatment: 10 to 30 mg orally per day until a response is evident. Then 2 to 4 mg until recovery.
Merck’s Manual 17th edition, section 1 Page 47 
These statements have not been evaluated by the FDA. This information is not intended to diagnose, treat, cure or prevent any disease or condition.

From Earl Mindell’s vitamin bible: This is an easy to understand book for those with less science:
B2 Riboflavin. also known as vitamin G.
Deficiency is Arobflavinosis, sores and rashes around mouth, lips, skin and genitalia.
Found in Milk, Liver, kidneys, yeast, cheese leafy green vegetables, fish and eggs (so you can see why being a vegetarian is a bad idea.)
No known toxic effects. If you are taking the pill, pregnant or lactating, you need more.
It is the most common deficiency in the American diet. (I’m Australian, we eat lots of fish and lamb’s liver).
Destroyed by light, hormones and alcohol and food cooked in water which dissolves it out. US RDA is 1.2 to 1.6 milligrams (mg) per day.