Hi, From the symptoms, it is suggestive that your friend was suffering from a infection of respiratory tract. The cause of black coloured phlegm may be due to following reasons: 1) Ingesting dark foods - Tiny particles of chocolates and other dark foods can stick to the mucus and change its color. 2) Inhaling Dirt and Dust - Small dirt particles can stick to the mucus and taint it. 3) Smoking - Smoke inhalation is yet another common cause of coughing up black phlegm. 4) Certain fungal infections - Fungal infections of the lungs that can make cough up black phlegm. 5) Old blood from Inflammation of airways - Coughing heavily in presence of inflammed airways may lead to bleeding or blowing nose in presence of inflamed nasal mucosa due to cold might have caused nasal bleeding which might have aspirated into the airway. To relieve coughing up black phlegm: Expelling black mucus is the way to get rid of it. Drink more water than usual to make it easier to expel mucus. Breathe deeply when coughing to get mucus out of respiratory passages. Inhaling steam can help loosen thick mucus and expel it by coughing. Nasal rinse helps eliminate black stuff from nose, which involves flushing a saline solution and sterile water through sinuses. (Saline nasal spray helps). Wearing a facemask to filter out dust and other environmental particles that can irritate respiratory passage. Stop smoking, if it is there. If your friend is suffering from repeated black coloured phlegm, then it would be advisable to consult a physician/pulmonologist to find out the cause. Hope this answers your question. Let me know if I can assist you further. Get well soon to your friend. Regards, Dr. Riddhi Shah