Introduction – Understanding Loss of Smell
Have you ever noticed that your morning coffee no longer has its familiar aroma, or that your favourite food seems less flavourful than usual? These changes may be signs that your sense of smell is not working as well as it should.
Loss of smell can develop suddenly or gradually. While some people experience a reduced ability to detect odours, others may lose their sense of smell completely.
Common causes include viral infections, nasal allergies, sinus problems and nasal polyps. Although some cases improve naturally, persistent or unexplained changes may require medical attention.
Understanding the possible causes and recognising when to seek help can make it easier to manage the condition appropriately.
What Is Loss of Smell?
Your sense of smell works through specialised receptors located high inside the nose. When you breathe in, tiny particles carrying different odours reach these receptors, which send signals to your brain to help you recognise smells.
Problems affecting this process may reduce or completely interrupt your ability to smell.
There are two main terms used to describe smell loss:
- Hyposmia: A reduced sense of smell, where familiar scents become weaker or harder to recognise.
- Anosmia: A complete loss of smell, where a person cannot detect odours.
Smell also plays an important role in how we experience food. This explains why meals may seem bland when your sense of smell is affected, even though you can still recognise basic tastes such as sweet, salty, sour and bitter.
What Are the Common Causes of Loss of Smell?
Several conditions can affect your ability to smell. Some temporarily interfere with airflow inside the nose, while others affect the receptors or nerves responsible for detecting odours.
1. Colds and Other Viral Infections
Respiratory infections, including the common cold, influenza and COVID-19, are frequent causes of smell changes.
During an infection, inflammation and swelling inside the nose may prevent odours from reaching the smell receptors. This can make familiar scents difficult to detect, particularly when nasal congestion is present.
However, certain viral infections may also affect the smell-sensing system itself. As a result, some people continue experiencing smell loss even after their blocked nose and other symptoms have improved.
Smell often returns following recovery, although the process may take longer for some individuals.
2. Allergic Rhinitis
Allergic rhinitis occurs when the immune system reacts to substances that are normally harmless, causing inflammation inside the nose.
In Singapore, common triggers include house dust mites, mould and allergens from pets. These can cause swelling of the nasal lining, making it more difficult for odours to reach the smell receptors.
People with allergic rhinitis may experience other symptoms, including:
- Frequent sneezing
- An itchy nose
- A watery or runny nose
- Persistent nasal congestion
When nasal inflammation is properly managed, the sense of smell may improve. However, ongoing symptoms should be assessed rather than automatically attributed to allergies.
3. Chronic Sinusitis
Chronic sinusitis involves ongoing inflammation in the nose and sinuses, with symptoms lasting at least 12 weeks. An ENT specialist may use a nasal examination or other tests to confirm the condition, as prolonged symptoms alone do not establish the diagnosis.
This inflammation may interfere with the area responsible for detecting smells. Unlike temporary congestion from a cold, the problem may persist for months.
Common accompanying symptoms include a blocked nose, mucus discharge, facial pressure and mucus dripping down the throat.
Reduced smell is one of the recognised symptoms of chronic sinusitis. However, an ENT assessment may be necessary to determine whether sinus inflammation is responsible, particularly when smell loss occurs without other obvious nasal symptoms.
4. Nasal Polyps
Nasal polyps are soft, non-cancerous growths that develop from inflamed tissue inside the nose or sinuses.
These growths can interfere with normal airflow and contribute to inflammation around the smell receptors. Depending on their size and location, they may cause a reduced or complete loss of smell.
Other possible symptoms include persistent nasal blockage, a runny nose, snoring and recurrent sinus problems.
Not everyone with nasal polyps experiences noticeable symptoms. A medical examination is therefore important to confirm whether these growths are contributing to smell difficulties.
5. Head Injuries
A head injury can sometimes affect the nerves or brain pathways involved in recognising smells.
Unlike smell loss caused by nasal congestion, this problem may occur even when the nasal passages remain clear.
The extent of recovery varies depending on the injury and which parts of the smell-sensing system have been affected. Some people regain their sense of smell, while others experience longer-lasting changes.
New smell loss following a head injury should be assessed by a healthcare professional.
6. Ageing and Other Less Common Causes
Our sense of smell may gradually become less sensitive as we grow older. This change can develop slowly, making it difficult to recognise immediately.
Certain medicines, prolonged exposure to harmful chemicals and some conditions affecting the nervous system may also contribute to smell changes.
However, losing your sense of smell does not automatically mean you have a serious neurological condition.
If the change is unexplained, particularly when it develops suddenly or continues to worsen, a medical assessment can help identify possible contributing factors.
Will Your Sense of Smell Come Back?
One of the most common concerns among people experiencing smell loss is whether their sense of smell will eventually return.
The answer depends largely on what caused the problem.
When smell loss occurs because of a cold or temporary nasal swelling, it may improve as the inflammation settles. However, recovery following certain viral infections can take weeks or months, and some people experience lasting changes.
Smell difficulties related to chronic sinusitis or nasal polyps may improve when the underlying condition is treated. In contrast, problems involving damaged smell nerves can be more difficult to reverse.
Recovery also differs between individuals, even when the underlying cause is similar.
Rather than relying on a fixed recovery timeline, it is important to monitor whether your sense of smell is improving. Persistent or unexplained changes should be medically assessed.
When Should You Seek Medical Help for Loss of Smell?
Not every change in smell requires urgent treatment. However, recognising when to seek medical advice can help identify underlying conditions that might otherwise go unnoticed.
When Should You See a Doctor?
If your sense of smell remains reduced after a cold has cleared, or does not begin to improve over the following weeks, consider speaking with a doctor. Sudden or unexplained smell loss should be assessed rather than waiting for symptoms to resolve.
You should also seek advice if:
- Your ability to smell gradually becomes weaker.
- Smell loss repeatedly occurs or affects your appetite and daily activities.
- You experience ongoing nasal blockage or unusual discharge.
- Your symptoms continue despite improvement in other nasal problems.
- Your sense of smell changes without an obvious reason.
In Singapore, a GP or polyclinic doctor can provide an initial assessment. Depending on your symptoms and examination findings, you may be referred to an ENT specialist for further investigation.
Which Symptoms Need Urgent Medical Attention?
Although smell loss itself is often not an emergency, certain accompanying symptoms may indicate a more serious problem.
If you experience sudden facial drooping, arm weakness or difficulty speaking, call 995 immediately in Singapore. These may be warning signs of a stroke, whether or not you have also noticed changes in your sense of smell.
A head injury accompanied by severe headache, repeated vomiting, confusion or loss of consciousness also requires emergency medical assessment.
Other concerning symptoms include a severe headache with visual changes or swelling around the eyes. These symptoms should receive urgent medical evaluation.
Persistent blockage affecting only one side of the nose, especially with unexplained bleeding, should also be assessed promptly by a doctor.
The important distinction is whether smell loss occurs alone or alongside symptoms that suggest a more serious condition.
How Does an ENT Specialist Investigate Loss of Smell?
An ENT specialist investigates smell loss by understanding your symptoms and checking for possible problems inside the nose.
The assessment is guided by your medical history, examination findings and whether additional tests are needed.
Reviewing Symptoms and Medical History
Your doctor will usually ask when the smell changes began and whether they developed suddenly or gradually.
They may also discuss recent respiratory infections, nasal allergies, sinus problems, previous head injuries and medicines you are taking.
Additional symptoms, such as nasal blockage, mucus discharge or changes in how food tastes, may provide useful clues.
This information helps determine whether the problem is more likely related to nasal inflammation, an obstruction or another cause.
Nasal Examination and Smell Testing
An ENT specialist may examine the nasal passages to look for swelling, nasal polyps or other abnormalities.
In some cases, a procedure called nasal endoscopy may be recommended. This involves using a thin camera to examine areas inside the nose that may not be clearly visible during a routine examination.
Standardised smell tests may also be used to assess how well you detect, distinguish and identify different odours.
Depending on the findings, a CT scan or other investigation may be considered. However, not everyone experiencing smell loss requires imaging.
Can Loss of Smell Be Treated?
Treatment for loss of smell depends on its underlying cause. There is no single treatment that works for every person, and improvement cannot always be guaranteed.
Treating the Underlying Cause
When smell difficulties are linked to allergic rhinitis or sinus inflammation, treatment may focus on reducing swelling and controlling the underlying condition.
A doctor may recommend suitable medicines, including nasal steroid sprays, depending on the diagnosis.
For nasal polyps, treatment often begins with medicines to manage inflammation. Surgery may be considered in selected cases when symptoms remain troublesome despite appropriate treatment.
However, surgery is not necessary for every patient and does not guarantee that normal smell will return.
Identifying the cause is therefore an important step before deciding on treatment.
Smell Training and Supportive Measures
Smell training involves regularly practising with familiar scents to support the recovery of smell function. It may benefit some people with persistent smell difficulties, particularly after viral infections, although results vary and improvement may take time.
This approach commonly involves smelling a selection of familiar scents, such as rose, lemon, clove and eucalyptus, while concentrating on each odour.
Practical safety precautions are also important when your sense of smell is reduced.
Make sure smoke detectors are working and check food expiry dates rather than relying on smell to judge whether food is safe. These measures can help reduce everyday risks while you are experiencing smell difficulties.
Conclusion – Understanding When Loss of Smell Needs Attention
Loss of smell can occur for several reasons, including viral infections, allergies, chronic sinusitis and nasal polyps. While some cases improve as the underlying condition resolves, others may require further medical investigation.
Persistent, unexplained or worsening smell changes should not be ignored, particularly when accompanied by other concerning symptoms.
A medical assessment can help establish the cause and identify suitable management options, giving you a clearer understanding of your condition and what to expect from recovery.
Frequently Asked Questions About Loss of Smell
1. Can you lose your sense of smell without a blocked nose?
Yes. Viral infections, head injuries and certain conditions affecting the smell-sensing system can cause smell loss even without nasal congestion.
2. Why can I taste food but not smell it?
Your tongue detects basic tastes, while your sense of smell contributes to flavour. Food may therefore seem bland when smell is reduced.
3. Can loss of smell affect your appetite?
Yes. Reduced enjoyment of food may affect appetite and eating habits, particularly when meals no longer have their familiar flavours.
4. Can certain medicines affect your sense of smell?
Some medicines may contribute to smell changes. Speak with your doctor before stopping or changing any prescribed treatment.
5. Can you gradually lose your sense of smell without noticing?
Yes. Gradual smell changes, including those associated with ageing, may be difficult to notice until familiar scents become harder to recognise.