Hi and thank you for your question. Dark areas around the corners of the mouth can be due to the following reasons: either a vitamin B deficiency or a high blood sugar. These can cause weakening of the skin at these delicate areas causing inflammation and a resulting increase in pigmentation. This can be treated by identifying the correct cause and then strengthening the skin while lightening it at the same time, but this must be done very gently. Ask your doctor and therapist to work together on this.