What does this mean?
The colour on its own says very little; discharge turns yellow or green in a common cold too, and that clears by itself. What tells them apart is the smell. A heavy, rotting smell comes from sulphur compounds made by bacteria that grow where there is no oxygen. That setting mostly forms in a space that has been closed off and cannot empty what is inside it.
The second telling detail is the side. A cold and an allergy affect both nostrils. If the smell comes from one side, a local source is looked for in the maxillary sinus on that side, the air space above your upper back teeth. The roots of the upper molars and premolars are separated from the floor of this sinus by thin bone, and in some people by the lining alone. If inflammation coming from a root passes the floor of the sinus, the discharge can become one-sided and foul-smelling.
Sometimes you are the only one who smells it and the people around you notice nothing; that suggests the source lies inside the nose. A foul-smelling discharge that starts after an upper back tooth has been taken out may go along with air or water passing from the mouth into the sinus. An antibiotic given without dealing with the tooth or the opening reduces the symptom for a while; the picture commonly returns once the course is finished.
What is looked for with a foul-smelling discharge is an area that has been closed off and cannot empty itself. That area can be inside the nose, but equally around a tooth next to the sinus, or in an opening left behind after an extraction.
Likely causes
What helps at home?
- Write down, with dates, any extractions, root canal treatments and implants carried out on your upper back teeth in the past year; that information helps directly in the search for the source.
- Do not use antibiotics left over at home on your own decision; medication taken before the source is found masks the picture for a while and clouds the examination findings.
- Do not blow your nose hard with both nostrils closed; it raises the pressure inside the sinus and can push the discharge the wrong way.
- Smoking and vaping devices slow down the rate at which the sinus lining cleans itself; staying away from them during this time makes healing easier.
- If water you take into your mouth escapes into your nose, or air passes from your nose into your mouth
- If swelling or redness has started in your cheek or your eyelid
- If one-sided face pain with a fever is getting worse day by day
- If your vision is blurred, you see double, or your eye movement is restricted
- If you have noticed numbness in your upper lip or your cheek
Frequently asked questions
- My tooth does not hurt; could a tooth still be the source?
- It could. Inflammation opening into the sinus most often comes from a tooth whose nerve has died, and these teeth do not hurt because they no longer respond to hot and cold. Sometimes the quiet inflammation under an old root canal treatment or a deep filling is responsible. That is why vitality tests on the teeth, and 3D imaging where needed, are added to the examination.
- I have taken antibiotics, so why does the smell keep coming back?
- An antibiotic reduces the load of inflammation. As long as the source stays where it is, the smell commonly returns once the medication is stopped. If the source is a tooth, treating or removing that tooth comes onto the agenda; if it is an opening left after an extraction, closing that opening does. Repeating the medication without touching the source is not expected to give a different result.
- I am the only one who can smell it; what does that mean?
- A smell only you notice suggests the source lies inside the nose. If the people around you notice it as well, causes inside the mouth and tonsil stones come onto the list too. The examination makes this distinction clear; the smell on its own does not give a diagnosis.
This content is for general information and does not replace an in-person examination. Symptoms overlap between conditions, and a diagnosis can only be made clinically.