Cough with red blood: what to know

A small streak can follow forceful coughing or irritation in the throat, nose or airways. Acute bronchitis may inflame airway lining; bronchiectasis can cause recurrent mucus and bleeding. Asthma, allergies, reflux and a common cold can also irritate the upper or lower airways, but blood should not automatically be attributed to them. The appearance matters: blood mixed with phlegm differs from dark vomit or bleeding from the gums. A clinician may need to examine your mouth, chest and breathing.

Stop smoking and avoid strenuous activity while arranging medical advice. Note whether the blood is bright red or dark, mixed with mucus or separate, and whether it is recurring. Bring a list of medicines, particularly blood thinners, and mention recent infection, travel, injury or lung disease. Do not use leftover antibiotics or assume a single streak is harmless if it returns.

Call emergency services for more than a trace of blood, repeated bleeding, severe breathlessness, chest or upper-back pain, fainting, confusion, blue lips, or a fast worsening illness. Seek prompt clinical assessment for any unexplained episode, even if it stops, and for fever, night sweats, weight loss, or a cough that persists. Children, older adults and people taking blood thinners need especially prompt advice.

Ask where the blood may be coming from, whether your medicines affect bleeding, what examination or imaging is needed, and which recurrence signs require emergency help.