A distorted sense of smell occurs when the perception of odors changes, making the familiar seem strange or unpleasant. This disruption in the olfactory system means the brain receives incorrect information from smell receptor cells inside the nose, leading to a warped interpretation of an odor. This phenomenon can impact the enjoyment of food and the ability to detect certain environmental smells.
Differentiating Smell Distortions
Two primary types of smell distortion exist. The first is parosmia, a condition where a scent that is physically present is misidentified. For someone with parosmia, the smell of coffee might be perceived as something foul, like garbage or rotten meat. This happens because the smell receptor cells fail to correctly transmit the odor’s true nature to the brain.
The second type is phantosmia, which involves smelling an odor that is not actually present. This is often described as an olfactory hallucination, where a person might detect scents like smoke or chemicals without any external source. Unlike parosmia, which is a misinterpretation of a real smell, phantosmia is the perception of a phantom one.
Common Causes of Olfactory Changes
The most frequent triggers for a distorted sense of smell are linked to damage of the olfactory neurons. Viral infections affecting the upper respiratory tract, such as the common cold, influenza, and COVID-19, are prominent causes. These viruses can harm the scent-detecting neurons that line the nasal cavity. For many, the onset of smell distortion becomes noticeable after recovering from such an infection.
Physical trauma can also lead to olfactory changes. A head injury can damage the olfactory nerves or the olfactory bulbs, the structures in the brain that receive signals from the nose. This damage disrupts the pathway that signals travel along, changing the perception of scents. The severity of the distortion can vary depending on the extent of the injury.
Chronic issues within the nose and sinuses are another source of smell distortions. Conditions like persistent sinusitis, nasal polyps, or severe allergies can interfere with the olfactory system. In some instances, exposure to certain toxic chemicals or dental health problems may contribute to the condition. Some neurological conditions can also present with smell distortion as a symptom.
The Diagnostic Process
A medical evaluation is the path to understanding a change in your sense of smell. A healthcare provider will begin by reviewing your medical history, paying attention to recent viral illnesses, head injuries, or a history of sinus problems. This background provides context for when the symptoms began.
Following the history review, a physical examination of the nose, throat, and nasal passages is performed. This allows the doctor to look for physical abnormalities, such as inflammation, nasal polyps, or signs of infection that could be affecting the olfactory system.
To assess the sense of smell, standardized “scratch and sniff” tests may be administered. These tests use booklets with various odorants that the patient must identify, helping to gauge the type and severity of the dysfunction. If the cause is not apparent, a referral to an Ear, Nose, and Throat (ENT) specialist may be necessary for more detailed testing or imaging, like a CT scan.
Management and Recovery Strategies
A primary method for regaining a normal sense of smell is olfactory training, or smell training. This therapy involves the deliberate and repeated sniffing of a curated set of potent scents. This includes essential oils like lemon, rose, cloves, and eucalyptus, which are sniffed twice daily for several months. The goal is to stimulate the olfactory neurons and encourage the brain to relearn and correctly classify different smells.
Alongside formal training, several practical coping strategies can help manage symptoms. It can be beneficial to avoid foods and other substances that trigger unpleasant distorted smells. Some people find relief by sticking to blander foods that are less likely to have strong, triggering odors. For severe cases of parosmia, using a nose clip during meals can provide some respite.
Patience is a component of the recovery process, as it can take time for the olfactory nerves to repair and for function to return. For many individuals, particularly those whose distortion was caused by a viral infection, the sense of smell can improve or return completely. The timeline for recovery varies widely, but consistent management strategies can support the gradual healing of the olfactory system.