Blood in phlegm with a sore throat: what to know

A viral cold, influenza, COVID-19 or tonsillitis can inflame the throat and make a small surface vessel bleed. Strep throat and glandular fever can also cause throat inflammation. Mucus from allergic rhinitis or acid reflux may repeatedly irritate the back of the throat. The blood may be from the nose, gums or tonsils rather than the lungs, especially when there is no cough. The symptom alone does not identify the cause.

Rest your voice, drink cool or warm fluids that feel comfortable, and avoid smoking, vaping and forceful throat-clearing. Look for mouth, gum or nose bleeding without scraping the area. Record whether the blood is streaked through mucus or appears separately, along with fever, swallowing difficulty and exposure to respiratory illness. Contact a clinician if the sore throat is worsening, the bleeding recurs, or swallowing fluids becomes difficult.

Seek urgent care for trouble breathing, inability to swallow saliva, drooling, rapidly increasing neck or throat swelling, severe one-sided throat pain, faintness or more than a small amount of blood. Same-day advice is sensible when high fever, dehydration, a muffled voice or significant weakness accompanies the throat symptoms.

Could the bleeding be from my throat, tonsils, nose or gums? Do I need a throat swab or another examination? Which symptoms suggest a bacterial infection? How should I manage pain while I wait to be seen?