A 17-year-old girl is brought by parents to physician with complaint of decreased sleep, irritability and lack of appetite leading to weight loss of around 4-5 kg in last 2 months. Patient herself repos feeling fine and in fact mentions having lots of energy. Physical examination shows a thin body habitus with a normal BMI, erythema of the nasal mucosa, and mild facial acne. Which of the following is the most likely diagnosis?

The diagnostic hallmark in this scenario is erythema of the nasal mucosa. Cocaine use disorder It is an alkaloid derived from Erythroxylum coca. It was used in 1884 as the first effective local anesthetic agent. Blocks reuptake of dopamine and norepinephrine. Snoing - Nasal mucosal erythema Increased energy Decreased appetite Jet black pigmentation of tongue Reduced need for sleep Cocaine bugs/Magnan phenomenon/Formication- tactile hallucinations seen in intoxicated state where the patient feels that insects are crawling all over his/her body. Chronic users Mood changes(euphoria, irritability) Weight loss secondary to decreased appetite. Treatment: Symptomatic and psychotherapy