Most sinus headaches begin during a cold as a result of congestion, so you may also have a blocked nose, sore throat, yellow or green nasal discharge, a mild temperature, or just feel tired and unwell.

Sinus congestion (sinusitis) is caused by a virus such as a cold or the flu. Occasionally it is caused by an allergy like hayfever or another health problem with the nasal passages, such as a tumor or a structural deformity.

If you have cold symptoms, your doctor will be more likely to diagnose a sinus headache rather than a migraine or a tension headache.

Antibiotics May Not Be Effective at Treating Sinusitis!

Antibiotics aren’t always effective at treating sinusitis, the root cause of a sinus headache, because most cases of sinusitis are caused by a virus and viruses don’t respond to antibiotics. However, sometimes retained nasal mucus leads to bacterial infection.

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