Cracked mouth corners: when a nutrient deficiency matters

A visible crack does not name the cause

DermNet describes prolonged saliva exposure as the common mechanism of irritation at the mouth corners. Examination can also identify local infection or contributing dental and skin problems. The same outward symptom can therefore require different treatment. [1]

Riboflavin is one possibility, not a diagnosis

ODS lists mouth-corner lesions and cracked lips among signs of riboflavin deficiency. Such deficiency is rare in the United States and often overlaps other nutritional deficiencies. A restricted diet or other symptoms can make nutritional assessment useful, but a photograph cannot determine which nutrient is missing. [2]

Match care to the underlying problem

Imagine persistent cracks despite taking a B-complex supplement. More tablets will not necessarily correct ongoing saliva irritation or infection. Arrange assessment for persistent or recurrent symptoms; treatment can address the local cause and any demonstrated nutritional problem together. [1][2]

Hypothetical example — distinguish a symptom from a confirmed nutrient diagnosis
Observation	Interpretation
Mouth-corner cracking	Several possible causes
Confirmed riboflavin deficiency	Correct the nutritional problem
Persistent symptoms despite supplements	Reassess the cause

Cracked mouth corners: when a nutrient deficiency matters — original article outline diagram — Original editorial diagram of this article’s sections; no product photograph or clinical finding is depicted.

Sources for this article

Angular Cheilitis: Symptoms, Causes, and Management with Images — DermNet
Source consulted: 2026-09-20. This is a reference resource, not a claim that we conducted the studies or tested a product.
Riboflavin - Health Professional Fact Sheet
Source consulted: 2026-09-20. This is a reference resource, not a claim that we conducted the studies or tested a product.