How Can a Stuffy Nose Cause Loss of Smell and Taste?

Smell, or olfaction, is one of the five human senses that is often overlooked. Yet, it plays an important role in the appreciation of food flavours and pleasant odorants (e.g. perfumes and flowers), detection of potential hazardous situations or materials (e.g. fire smoke and spoiled food) and is integral in a person’s daily social interactions and awareness of his or her surroundings.

Often we only recognise the importance of our sense of smell when we lose it – such as when it’s temporarily dulled by a cold, flu, or sinusitis. But how can symptoms like a stuffy nose cause loss of smell? Or even loss of taste?

In this short blog, Dr Gan explains why we can’t smell when we have a cold and discuss some of the common causes of loss of smell and taste, an area that is often neglected not only by patients but also by some Family Physicians and Ear, Nose & Throat (ENT) Specialists.

Causes of Loss of Smell After a Stuffy Nose or Sinus Infection

Caption: Figure 1– The location of the olfactory nerves in the nose. When smell is detected by the olfactory nerves, the smell information is carried by signals that are transmitted by the olfactory bulb and olfactory tract to the brain.

Most of us have had a bad cold, flu, or sinus infection (sinusitis) at some point in our lives (some more frequent than others). During these episodes, sometimes we would experience a temporary reduction or a total loss of our sense of smell and taste. The nerves responsible for detecting smell (also called the olfactory nerves) are located at the roof of the nasal cavity (deep and high inside the nose)(Figure 1).

When one has a cold, flu, or sinusitis, there is swelling and a lot more mucous in the nose. The mucous and swelling in the nose prevent the smell (odorant) from reaching the top of the nasal cavity. Hence, the smell never reaches the smell nerves and the nerves are not stimulated. After your nose or sinus infection settles, the swelling and excessive mucous resolve. The odorant is then able to reach the smell nerve fibres again. Hence, you regain your sense of smell.

Now you understand how a stuffy nose can cause loss of smell. But what about the loss of taste that commonly accompanies it? While it seems unbelievable, your sense of taste (ability to detect sweetness, sourness, bitterness, saltiness, and umami) is actually normal during a cold or sinus infection. Your food seems “tasteless” during a cold because your appreciation of food flavour and odour comes from your ability to smell! So don’t blame your taste buds for the loss of flavour. It is all due to your stuffed-up nose!

What Happens If My Post-Sinusitis Loss of Smell Persists?

Unfortunately for some, during the cold, flu, or sinus infection, the loss of sense of smell is not due to a physical blockage. It is due to the virus, bacteria, or inflammation causing damage to the smell nerves during the infection. If the smell nerves are damaged, the loss of smell is often permanent and irreversible. Most often, the cause for prolonged loss of sense of smell is unknown (Idiopathic). Other common causes of prolonged loss of sense of smell include severe head trauma (potentially causing shearing injury to the smell nerve), chronic sinusitis, nasal polyps, and rhinitis. In rare instances the loss may be due to a nose or brain tumour!

A decrease in sense of smell (relative to what is considered normal for the patient’s age-group) is also increasingly recognised as an early marker for neurodegenerative conditions such as Parkinson’s disease and Alzheimer’s disease.

If your sense of smell has decreased, you should consult an ENT doctor in Singapore for further assessment. The specialist will be able to assess your symptoms and advise on suitable treatments, such as allergic rhinitis treatment or sinus surgery, depending on the severity of your condition.

Best wishes,

Dr Gan Eng Cern
ENT Specialist Singapore