Why do I keep smelling something sweet? The Possible Causes Behind a Phantom Odor

Over 6% of Americans over age 40 experience phantosmia, the medical term for phantom smells. If you find yourself wondering, 'Why do I keep smelling something sweet?' it's important to understand the various potential causes, ranging from simple diet changes to more complex underlying health conditions.

Quick Summary

Detecting a persistent sweet odor can be caused by conditions like phantosmia, dietary factors, certain metabolic conditions such as ketoacidosis, or rarer neurological disorders, requiring careful consideration of accompanying symptoms.

Key Points

• Phantosmia: A phantom sweet smell is medically known as phantosmia or an olfactory hallucination, meaning you perceive an odor that isn't there.

• Sinus Issues: Infections like sinusitis or nasal polyps can cause inflammation that disrupts your sense of smell, leading to phantom odors.

• Metabolic Changes: Conditions like diabetic ketoacidosis (DKA) or following a ketogenic diet can produce ketones that cause a sweet or fruity smell on your breath.

• Neurological Concerns: Rarer but more serious causes include migraines, head injuries, seizures, or brain tumors that affect the brain's olfactory pathways.

• Dietary Factors: Certain foods and supplements, such as fenugreek, can alter your body odor to smell like maple syrup.

• When to See a Doctor: Seek medical attention if the sweet smell is persistent, severe, or accompanied by symptoms like confusion, excessive thirst, or sudden weakness.

Understanding Phantosmia: The Phenomenon of Phantom Smells

Phantosmia, or an olfactory hallucination, is the medical term for smelling something that isn't there. While many phantosmia sufferers report smelling unpleasant odors like burning rubber or spoiled food, some experience a pleasant, sweet smell. This can happen in one or both nostrils and may occur intermittently or constantly. Identifying the cause is crucial, as it can be as simple as a sinus infection or as serious as a neurological condition.

Sinus and Nasal-Related Causes

Inflammation or infection within the nasal passages is a common culprit for phantom smells. The olfactory system, located in the nose and sinus cavities, is responsible for detecting smells, and any disruption can cause false signals to be sent to the brain.

• Upper Respiratory Infections: A common cold, the flu, or COVID-19 can damage the sensitive nerve tissue in the nose, causing temporary alterations in your sense of smell. As you recover, these phantom smells may appear.
• Chronic Sinusitis and Nasal Polyps: Chronic inflammation of the sinuses (sinusitis) and non-cancerous growths called nasal polyps can both interfere with the normal function of the olfactory system. The swelling and irritation can cause the olfactory neurons to misfire, triggering a sweet, phantom scent.
• Exposure to Toxic Chemicals: In some cases, exposure to toxins such as mercury or lead can damage the olfactory system, leading to phantom smells.

Metabolic and Dietary Factors

Sometimes, the sweet smell is not a phantom, but is actually being produced by your own body due to a metabolic change. These smells are often detected on your breath, sweat, or urine.

• Diabetic Ketoacidosis (DKA): For people with uncontrolled diabetes, a life-threatening complication called DKA can cause a fruity or sweet smell on the breath and body. This occurs when the body, unable to use glucose for fuel due to lack of insulin, begins to break down fat, producing acidic ketones. Other symptoms include excessive thirst, frequent urination, nausea, and confusion.
• Ketogenic Diet (Keto): Individuals on a keto diet intentionally enter a state of ketosis to burn fat for energy. This process also produces ketones, which can be exhaled and cause a temporary fruity or sweet odor on the breath.
• Fenugreek: This herb, used in many cuisines and as a supplement, contains a compound called sotolone. When metabolized, it can cause sweat and urine to smell like maple syrup.
• Maple Syrup Urine Disease (MSUD): This rare, inherited genetic disorder prevents the body from breaking down certain amino acids. The buildup of these substances causes the urine, sweat, and earwax to smell like maple syrup or burnt sugar.

Neurological and Other Health Conditions

When the cause is not in the nose or related to metabolism, the source of the phantom smell can be neurological.

• Migraines: Some people experience an aura of altered senses before or during a migraine, and this can include a phantom sweet smell.
• Epilepsy: Certain types of seizures, particularly temporal lobe seizures, can trigger olfactory hallucinations as a symptom.
• Head Injury or Trauma: A blow to the head can damage the olfactory nerves or the brain’s olfactory center, leading to phantosmia.
• Brain Tumors: Although rare, a tumor in the olfactory region of the brain can cause persistent phantom smells.
• Neurodegenerative Diseases: Phantosmia has been associated with conditions like Parkinson's and Alzheimer's disease, especially as a sign of neurological degeneration.
• Aging: The risk of olfactory disorders, including phantosmia, increases with age, possibly due to a natural decline in sensory function.

When to Seek Medical Attention

While occasional phantom smells might not be serious, you should consult a healthcare provider if the sensation is persistent, severe, or accompanied by other concerning symptoms. They can perform a thorough evaluation, which may include imaging studies like a CT scan or MRI to identify the underlying cause. Your doctor may also refer you to a specialist, such as an otolaryngologist (ENT) or a neurologist.

Comparing Common Causes of Sweet Smells

Feature	Phantosmia (General)	Diabetic Ketoacidosis (DKA)	Keto Diet	MSUD	Fenugreek	Neurological Condition
Source	Phantom (not real)	Body's metabolism	Body's metabolism	Body's metabolism	Digested food	Brain/nerves
Sensation	Perceived odor	Real, exhaled odor	Real, exhaled odor	Real, exhaled odor	Real, exhaled odor	Perceived odor
Additional Symptoms	None (may indicate underlying issue)	Thirst, fatigue, nausea, confusion	Weight loss, fatigue (keto flu)	Vomiting, lethargy, developmental delays	None	Headaches, seizures, cognitive changes
Urgency	Non-urgent (unless persistent)	Medical Emergency	Normal adaptation period	Urgent (especially in infants)	Harmless	Depends on condition (urgent if suspected)
Treatment	Addressing underlying cause	Insulin and fluids	None (temporary side effect)	Strict diet, medical management	Stopping fenugreek intake	Addressing underlying neurological issue

Conclusion: Taking Persistent Symptoms Seriously

Smelling something sweet that isn't there can be a puzzling and unsettling experience. While some causes, like a sinus infection or dietary choice, are temporary and benign, others, such as uncontrolled diabetes or a neurological issue, require prompt medical attention. Pay close attention to any accompanying symptoms, and don't hesitate to consult a healthcare professional for an accurate diagnosis and treatment plan. Your sense of smell can provide valuable clues about your overall health. To learn more about olfactory disorders, you can visit the National Institute on Deafness and Other Communication Disorders website.

Frequently Asked Questions

What is phantosmia?

Phantosmia is a medical term for an olfactory hallucination, where a person smells odors that are not actually present in their environment.

Can a sinus infection cause me to smell something sweet?

Yes, chronic sinusitis or other sinus issues can cause inflammation that irritates the olfactory nerves, leading to a phantom sweet smell.

Why would my breath smell sweet if I have diabetes?

A sweet or fruity smell on the breath can be a sign of diabetic ketoacidosis (DKA), a dangerous complication where the body produces ketones due to a lack of insulin.

Could a ketogenic diet be the cause?

Yes, the ketogenic diet puts your body in a state of ketosis, producing ketones that can be exhaled and cause a temporary sweet or fruity odor on the breath.

Is it serious if I keep smelling something sweet?

The seriousness depends on the cause. It could be harmless, but it can also be a symptom of a serious condition like uncontrolled diabetes or a neurological issue. You should consult a doctor to be sure.

Can certain foods make my sweat or urine smell sweet?

Yes, some foods and herbs, most notably fenugreek, contain compounds that are metabolized and can cause a sweet, maple syrup-like smell in sweat and urine.

When should I see a doctor about a phantom sweet smell?

You should see a doctor if the phantom smell is persistent, severe, or if it's accompanied by other worrying symptoms such as confusion, excessive thirst, or headaches.