Some people have a bad or strange smell that seems to come from inside the nose. Possible causes include problems with the sinuses, nasal passages, and mouth.

Conditions that may cause a bad smell in the nose include:

  • acute and chronic sinusitis
  • mouth or tooth infections
  • dry mouth
  • some foods, drinks, and medications
  • conditions associated with hallucinations or olfactory damage

Most conditions that cause a bad smell in the nose are not life threatening. However, if the bad smell is severe or chronic, it can negatively impact someone’s quality of life and may require medical attention.

This article discusses the causes of a bad smell in the nose, as well as treatments and prevention methods. Several conditions are commonly associated with a bad smell inside the nose, and we cover many of them below.

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A sinus infection, called sinusitis, affects around 31 million people in the United States. This term refers to inflammation of the sinuses, which can lead to nasal congestion. In turn, this can interfere with a person’s sense of smell.

The condition can also cause bad breath and a discolored, bad-smelling discharge in the nose and back of the throat, all of which may create a bad smell in the nose.

Acute sinusitis typically lasts for around 3–8 weeks, while chronic cases can last for longer than 8 weeks. A species of bacteria usually causes sinusitis, though viruses, fungi, and molds can also cause it.

Instead of sinusitis, some children may experience adenoiditis. This refers to inflammation of the adenoids in the throat. This can also cause bad breath and a weird smell in the nose.

Cavities, or holes in the teeth, can trap bacteria that release unpleasant gases. For example, the bacteria that live in the mouth can produce compounds containing sulfur. These compounds can smell like rotten eggs. Cavities usually arise due to tooth decay or gingivitis, which can include inflamed gums or gum disease.

These unpleasant gases, which become foul-smelling odors, can connect to the back of the nose and cause a bad smell in the nose.

Poor oral hygiene can increase the risk of developing plaque and tartar. Plaque is a collection of bacteria that can live in the mouth. When plaque hardens, it is known as tartar. Having plaque and tartar can increase the risk of developing dental problems.

Maintaining proper oral hygiene can help remove food and bacteria in the mouth that may be contributing to bad smells.

Read on to learn more about removing plaque and tartar.

Foods and drinks are full of microscopic molecules that stimulate the sense of smell. Most of our ability to enjoy the taste and smell of food and drink relies on molecules traveling to the sinuses through a passageway near where the roof of the mouth connects to the nose.

All foods release smells as our bodies break them down and digest them. However, certain foods and drinks, as well as some drugs, may linger in the mouth or trigger an unpleasant smell in the nose. These may include:

  • garlic and onions
  • coffee
  • spicy foods
  • alcohol
  • certain diets, such as the ketogenic diet.

Dry mouth, or xerostomia, can develop when the flow of saliva in the mouth is not adequate. Saliva, or spit, plays an important role in oral health. Not only does it wash away food and debris from teeth and gums, but it also helps to prevent cavities and other infections in the mouth.

As such, when there is not enough saliva present, a person is more likely to experience conditions that can cause a bad smell or taste in the mouth and nose.

Dry mouth can occur due to breathing through the mouth, dehydration, or health conditions, such as Sjögren’s syndrome. It is also a common side effect of several medications, such as:

  • pain medications
  • decongestants
  • antihistamines
  • diuretics
  • radiation therapy

Tobacco products contain chemicals that stain and weaken the teeth and gums, thus increasing the risk of tooth and gum disease. Tobacco also contributes to the amount of sulfur producing bacteria present in the mouth. Tobacco itself can also give the breath an unpleasant odor.

Smoking can also reduce someone’s ability to taste and smell food properly, which may cause someone to smell odors that they perceive as foul, but which may not actually be bad.

People with phantosmia smell things that are not there. It occurs when a condition interferes with a person’s sense of smell.

Everyone with phantosmia smells a slightly different scent, but most people experience something that smells:

  • burnt
  • metallic
  • similar to chemicals
  • rotten
  • decayed
  • similar to feces

Evidence suggests that phantosmia occurs in roughly 11% of people with smell disorders. Smelling disorders, such as phantosmia, can occur for a variety of reasons including:

  • colds and flu
  • sinus infections
  • nasal polyps
  • head injury
  • some conditions that affect the nervous system, such as Alzheimer’s disease and Parkinson’s disease
  • older age
  • smoking
  • hormonal changes
  • dental problems
  • exposure to certain chemicals
  • radiations treatment for head and neck cancers
  • certain medications, such as antibiotics and antihistamines

Some digestive conditions, such as acid reflux, can cause bad breath and a bad taste in the mouth.

Also, although fairly benign conditions are usually behind a bad or unusual smell in the nose, it is rarely linked to more systemic or serious health conditions, which may include:

  • diabetes, which may cause a sweet smell
  • liver disease, which may cause a strong musty smell
  • kidney disease, which may cause an ammonia-like smell

The best way to treat a bad smell in the nose depends on the underlying condition. That said, there are some home remedies that can help reduce a bad smell in the nose:

Try a homemade saltwater rinse

Using a saltwater rinse can help temporarily reduce the intensity of a bad smell in the nose.

To make a saltwater rinse at home:

  1. Boil water, then leave to cool.
  2. Mix 1 teaspoon (tsp) of salt and 1 tsp of baking soda into the water while it is still quite warm.
  3. Wash the hands well with soap and water.
  4. Standing over a sink or bowl, pour some of the mixture into the cupped palm of one hand.
  5. Lean over the sink and sniff some of the mixture into one nostril at a time, then let it run out of the nose. It may help to keep the other nostril closed with a finger while sniffing.
  6. Repeat steps 4 and 5 a few times.
  7. Dispose of any unused solution.

A person does not need to use all of the solution, but make a fresh batch each day. Do not reuse any left over from the day before.

People can also purchase sachets from a pharmacy to help make a saltwater solution, and devices to help them rinse their nose.

Drinking water

Dehydration can contribute towards bad breath. As such, regularly consuming beverages such as water to maintain hydration can help prevent bad smells in the mouth and nose. Additionally, consuming foods that require a lot of chewing, or sugar-free candies or gums can help promote saliva production.

Read on to learn more about how much water to drink.

Practice good dental hygiene

Having good oral hygiene can help treat several conditions that cause a bad smell in the mouth and nose. Some recommendations from the American Dental Association include:

  • brushing the teeth with a fluoride-based toothpaste for 2 minutes twice daily
  • flossing daily
  • cleaning the tongue daily with a toothbrush or a tongue scraper
  • cleaning dentures and other dental gear daily
  • chewing sugarless gum for 5 minutes after meals
  • cutting back on foods and drinks that contribute to dehydration, such as coffee and alcohol
  • quitting smoking and tobacco use
  • having frequent dental checkups and cleanings

Home remedies over-the-counter (OTC) medications

If sinusitis is causing a person to experience bad smells in the nose, some home remedies and OTC drugs can help to relive symptoms. These can include:

  • a warm compress over the nose and forehead to help relieve sinus pressure
  • decongestants
  • saline nasal sprays
  • inhaling steam from a bowl of hot water or shower

Read on to learn more about medications for sinus pressure.

Depending on the condition that causes it, making certain lifestyle changes can help reduce the risk of developing a bad smell in the nose. For example, this may include practicing good oral hygiene and quitting smoking. Other lifestyle changes may include:

  • maintaining hydration
  • eating fiber-rich foods
  • avoiding foods and drinks that cause dehydration, such as caffeine and alcohol
  • treating nasal or sinus inflammation
  • avoiding foods and drinks that cause bad smells in the mouth, such as garlic and onions
  • talking to a doctor about reducing or switching medications that may be linked to dry mouth
  • managing health conditions that may contribute towards bad breath

Some FAQs about weird smells in the nose may include:

Why is there a smell coming from my nose?

Many different health condition can cause a bad smell to come from the nose. These can include sinus infections, dental problems, dry mouth, smoking, and digestive issues. Certain foods, beverages, and drugs can also result in odors coming from the nose.

What is a phantom odor in the nose?

This refers to an olfactory hallucination, or phantosomia. This describes when a person can detect smells that are not actually present. The phantom odor people notice can differ from person to person and may be foul or pleasant.

Why do I smell a weird smell?

Allergies, nasal polyps, and certain illnesses such as a cold, flu, or COVID-19 can cause changes to a person’s sense of smell. These can cause a loss of smell (anosmia), a reduction in sense of smell (hyposmia), or changes to how things smell (parosmia).

Sinusitis, mouth infections, and certain foods, drinks, and lifestyle habits are usually behind bad smells in the nose.

People can usually get rid of bad smells in the nose by using home remedies, trying OTC medications, and making lifestyle changes.

However, a bad smell in the nose can decrease someone’s quality of life and cause complications such as malnutrition. It can also be a sign of underlying conditions that require medical treatment.

A person can talk with their doctor about severe or chronic bad smells in the nose, those that do not respond to home remedies, or those that last longer than a week.