What is Anosmia (Loss of Smell)? Symptoms, Causes and Treatment

Anosmia (Loss of Smell - Olfactory Blindness)

Anosmia medically means the complete loss of the sense of smell. Although the nose may appear to function, scent signals do not reach the brain. While this condition can sometimes develop following a temporary infection, in some individuals it can be congenital. Although smelling may not seem like a critical part of life, it is actually directly related to emotional memory, appetite, safety, and social relationships. Sometimes it can result in failing to notice dangers such as fires or gas leaks, and sometimes it can lay the groundwork for psychological collapses such as depression.

What is Anosmia?

The condition of anosmia is when a person completely loses their sense of smell. This medical term is also known colloquially as olfactory blindness or inability to smell. Scents in the air we breathe through our noses are transmitted to the relevant center in the brain via olfactory nerves; however, when this communication is disrupted for any reason, the person cannot perceive any scent. Anosmia can sometimes be temporary and sometimes permanent. Many different causes, from upper respiratory tract infections to head traumas, sinusitis to neurological diseases, can lead to this condition. Sometimes a person not only loses their sense of smell but also experiences a decrease in their sense of taste because the senses of taste and smell are closely linked. Anosmia is not just a physical health problem; it has social, emotional, and psychological dimensions, and in this respect, it is a condition that must be taken seriously.

What Are the Symptoms of Anosmia?

The most prominent symptom of anosmia is, of course, the inability to perceive scents; however, this awareness often develops over time rather than suddenly. Some individuals consult a doctor by realizing they cannot perceive certain scents. When others come in with complaints of loss of taste, it turns out that their sense of smell has also weakened. The symptoms of olfactory blindness include:

Being unable to notice frequently encountered scents in daily life (e.g., coffee, food, perfume),

Perceiving tastes as faint or bland,

A decrease in the pleasure derived from meals,

Loss of appetite and weight loss in some cases,

Emotional depression, social withdrawal.

What Causes Anosmia?

The cause of anosmia can sometimes be as mundane as a simple upper respiratory tract infection, or it may point to a more complex clinical picture affecting the nervous system. Here are some of the common causes:

Upper respiratory tract infections: Short-term anosmia can develop especially after the flu and cold. Being unable to smell through the nose is a temporary problem frequently encountered after respiratory tract infections.

COVID-19: With the pandemic, sudden-onset loss of smell, sometimes lasting for months, has begun to be observed more frequently.

Sinusitis: Particularly chronic sinus infections can lead to anosmia by blocking the olfactory pathways.

Nasal anatomical disorders: Structural conditions such as nasal polyps and deviation.

Traumas: Blows to the head or nasal region can cause damage to the olfactory nerves.

Neurological diseases: A decrease in the sense of smell can also be seen as an early symptom in diseases such as Parkinson's and Alzheimer's.

Congenital causes: Genetic failure of the olfactory centers to develop.

How is Anosmia Diagnosed?

A detailed inquiry and examination are required for a proper evaluation of a person experiencing loss of smell. In the first step, the patient's history is of great importance. The physician tries to gather clues about the underlying cause by asking when the loss of smell started, whether it developed suddenly or over time, and in which situations it increases or decreases. In addition, the patient's past infections, traumas, medications used, and any accompanying diseases are questioned in detail.

Physical examination, especially an ear, nose, and throat (ENT) examination, is indispensable to the diagnostic process. Anatomical obstacles that could block the olfactory pathway, such as polyps, deviation, and edema inside the nose, are observed. If the physician suspects a structural problem, the interior of the nose is examined more closely with an endoscopic examination. Special smell tests can be applied to clarify the diagnosis. The best known of these are "olfactory recognition tests," which measure whether a person can recognize certain scents. Easily distinguishable scents such as orange, mint, and coffee are used in these tests. Information is obtained such as whether the patient can perceive and identify these scents, how quickly they distinguish them, and which ones they cannot notice at all. While some tests only determine the threshold of perception for a scent, others also evaluate the ability to discriminate.

If it is thought that the loss of smell may be related to a neurological disease, advanced imaging methods such as magnetic resonance imaging (MRI) or computed tomography (CT) are resorted to. In particular, the olfactory pathways in the brain, the olfactory bulb, and related brain regions are thus evaluated in detail. Blood tests may also be performed in some cases; for example, to investigate underlying systemic causes such as vitamin deficiencies or hormonal disorders.

How is Anosmia Treated?

The fundamental principle of anosmia treatment is to find the source of the problem and produce a solution targeting that source; therefore, treatment is not applied the same way to everyone; it is personalized. For the treatment of olfactory blindness, causes such as infection, trauma, or neurological disorders must first be determined. For this reason, there is no single standard treatment. Primarily, both the duration and the causes are focused on to understand whether the loss of smell is temporary or permanent.

Infection-related loss of smell, which is one of the most common causes, usually resolves over time without requiring treatment; however, if symptoms are prolonged, physicians typically prescribe anti-inflammatory sprays or medications that reduce intra-nasal edema. These treatments open up the interior of the nose, making it easier for scent particles to reach the nerve endings. If anosmia is caused by polyps or structural disorders inside the nose, surgical intervention may be required. In particular, the sense of smell can be restored by removing large polyps or correcting a deviated septum causing nasal congestion. Such operations are generally performed using endoscopic methods, and the recovery process is short.

In recent years, especially in loss of smell developing after COVID-19, a method called "olfactory training" has drawn significant attention. In this method, the person performs nose exercises twice a day with specific scents (e.g., lemon, eucalyptus, clove, rose). This practice aims to re-stimulate damaged olfactory nerves and allow the neural pathways to reorganize themselves.

Although it may seem simple, it is a form of treatment supported by science and yields positive results when applied regularly. In neurological or congenital anosmia cases, a direct recovery may not be possible. In such cases, treatment is mostly supportive. Approaches such as recommendations to increase the patient's quality of life, safety precautions (e.g., using gas detectors), and psychological support come to the fore because emotional effects such as social isolation, anhedonia (inability to feel pleasure), and depression can be observed in individuals experiencing permanent loss of smell.

It is very important to be patient during the treatment process and to remain in constant communication with the physician. While anosmia is sometimes a problem that can be resolved in a short time, it can sometimes require a long recovery process. With the right approach, especially in temporary and treatable causes, it is possible to largely regain the sense of smell. Another key to success in treatment is the patient's active participation in the process and regular performance of the recommended exercises.

Frequently Asked Questions

Inability to smell can manifest in both temporary and permanent forms. The duration and severity of this condition largely depend on the underlying cause. For example, anosmias developing due to upper respiratory tract infections, allergies, or short-term nasal congestions are mostly temporary. When the treatment process is entered or the infection is overcome, the sense of smell usually returns spontaneously. One of the symptoms developing with the COVID-19 pandemic is sudden-onset loss of smell. It has now been scientifically clarified that the virus has a direct effect on olfactory receptors and nerve endings inside the nose. Many people have reported losing their sense of smell in the first days of the disease, even before fever or cough starts. For most people, this condition improves spontaneously within a few weeks. Being completely unable to smell is a loss that negatively affects both a person's social life and safety. However, in some individuals (especially those who have had a severe form of the disease, elderly individuals, or those with chronic conditions), this loss of smell can last for months. In some cases, it can even be permanent. The reason for such permanence is that the virus causes long-term or irreversible damage by affecting the olfactory nerves or the relevant centers of the brain. A person experiencing anosmia mostly expresses feeling a deficiency not only in smell but also regarding the sense of taste. This condition actually stems from the nose not working, not the tongue. This difference becomes even more pronounced, especially in foods with complex tastes (e.g., soup, spicy dishes, coffee). Tastes are perceived as flat, bland, or identical. This can negatively affect both eating habits and appetite. Sinusitis is one of the most common causes of anosmia. Sinuses are hollow spaces located around the nose that produce mucus. The clinical picture formed with the inflammation of these spaces is called sinusitis. When sinusitis is present, these areas swell and become blocked, and scent particles that need to be transmitted from the nose to the brain cannot pass through. Acute sinusitis usually develops following an infection and is temporary. However, in chronic sinusitis, especially if conditions such as polyp formation or continuous nasal congestion are present, this loss of smell can be prolonged or even become permanent. In anosmias caused by sinusitis, decongestant treatments, anti-inflammatory medications, or surgical methods if necessary can be applied. When the opening of the sinus channels is achieved with appropriate treatment, the sense of smell returns in most cases. Some people are born without a sense of smell at all. This condition is medically called congenital anosmia. Congenital olfactory blindness is usually rare and associated with a genetic condition. While sometimes seen on its own, it can sometimes appear alongside other congenital syndromes (such as Kallmann syndrome). In these individuals, the olfactory nerves are either underdevelopment or the olfactory centers in the brain have not formed completely. Recovery is not possible in such cases because the problem is not merely in signal transmission, but in the structural absence of the center where the signal would be perceived. These individuals generally notice the loss of smell only through feedback from their social circle or later in life. The primary medical specialty that should be consulted with the complaint of anosmia, i.e., loss of smell, is the ear, nose, and throat (ENT) department. An ENT specialist evaluates the internal nasal structure, respiratory tracts, and olfactory pathways to determine whether the underlying problem originates from the nose.

In some cases, especially if neurological causes are suspected, a neurology specialist may also be involved in the process. Anosmia has a treatment, but the form of the treatment process is determined according to the cause of the loss of smell. It cannot be expected that the same treatment method will work for every patient. For example, medical treatments are quite effective in temporary losses of smell due to nasal congestion or sinusitis. Corticosteroid sprays, nasal irrigation solutions, or antihistamines are used in this process. The tests most commonly used to evaluate loss of smell are olfactory recognition and olfactory threshold tests. In the recognition test, the person tries to perceive and name different scents. In the threshold test, the lowest intensity at which they can feel the scent is measured. These tests help understand the degree and cause of anosmia. Imaging methods such as MRI can also be added when necessary. Loss of smell can seriously affect mood. Scents have a strong bond with emotions; the pleasure of eating, memories, and social relationships are intertwined with this sense. Depression, anxiety, feelings of loneliness, and loss of appetite are frequently seen in individuals experiencing anosmia. Therefore, psychological support is also important during the treatment process. In many cases, the sense of smell returns, especially in losses due to infections or blockages. In anosmia developing after COVID-19, most people also recover within a few weeks or months. Methods such as olfactory training can support the recovery process; however, losses originating from congenital or nerve damage can be permanent.

Losses experienced in the sense of smell are an important health problem directly affecting quality of life and safety. Anosmia can be related to a simple infection or can be a harbinger of different underlying diseases. Therefore, it is of great importance that individuals experiencing loss of smell undergo an expert evaluation without wasting time.

Our experienced Ear, Nose, and Throat (ENT) specialists working at Hisar Hospital Intercontinental evaluate the cause of the loss of smell using advanced diagnostic methods and create personalized treatment plans. If you are also experiencing a decrease or loss in your sense of smell, you can make an appointment with our expert Ear, Nose, and Throat (ENT) department doctors and contact us for detailed information.