What causes a musty smell in the nose?

Changes in your sense of smell and taste are rarely life-threatening, but they can have a significant impact on your quality of life. Smell and taste are closely linked, so many people who lose their sense of smell find that food loses much of its taste as well. You can recognise basic tastes - bitter, sweet, salty, sour and umami - the taste of meaty/savoury substances - without needing smell. However, more complex flavours need both senses to appreciate them fully. In fact, most of the flavour of food is largely due to its smell.

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Like taste, smell is a chemical sense. Receptors in your nose turn messages from smells received into electrical signals for the brain to interpret. You can smell food through your nose without tasting it. But when you're eating, the smells also travel to the back of your nose from the back of your mouth.

Causes of a bad smell in the nose

The source of a bad smell in the nose can vary. There may be several reasons behind it, but let's explore the most usual ones:

Common cold

One of the most typical reasons for a distorted sense of smell is the common cold. The build-up of mucus blocks the delicate chemoreceptors that line the nose, affecting their ability to be stimulated and send those electrical signals.

Hay fever

Hay fever, which can also lead to a build-up of mucus and a blocked - along with a runny, itchy - nose, can have the same effect. However, these conditions are unlikely to lead to abnormal smells - partial or complete loss of sense of smell is more likely.

Sinusitis

A more common reason for a musty smell in the nose is a sinus infection. This can be acute or chronic.

Acute sinusitis is generally associated with:

• Pain over the front of your face.

• A blocked or runny nose.

• Fever.

• An unpleasant-tasting drip down the back of your nose into your throat.

Chronic sinusitis - pain that lasts for more than 12 weeks - is less prominent but a runny nose and reduced sense of smell are still common.

Mouth infections

Mouth infections or problems with your teeth can also cause an unpleasant sense of smell.

Nerve Problems

A rarer cause of problems with smelling is partial damage to the nerve involved in smell (the olfactory nerve). This can happen as a result of a head injury or a stroke.

Nasal or Sinus cancers

Very rarely, cancers in the nose or sinus can cause a change in smell, reduced or loss of smell.

Other causes of a bad smell in the nose

Oral health

Because smell and taste are closely linked, other problems which affect your mouth can also result in a change in your sense of smell. Poor oral hygiene, tooth decay, inflamed gums and smoking are obvious culprits.

Acid reflux

Reflux from your gullet (oesophagus) can cause a nasty taste in the back of your throat which can affect your sense of smell. If your symptoms are severe or persistent, see your doctor. They may consider tests and possibly a referral to an ear, nose and throat (ENT) specialist who can examine the inside of your nose with a small flexible telescope called an endoscope.

What is a phantom odour in the nose?

Our sense of smell can sometimes be tricked into conjuring up phantom odours. There are two main conditions that might create a sense of foul smell in the nose.

Phantosmia

If you have phantosmia, you might smell things that aren't actually there. People with phantosmia often sense a foul odour like burning or sewage. Other smells include cigarette smoke or chemicals, but this can vary.

Parosmia

Parosmia is a condition where a person might experience a distorted sense of smell. Familiar scents may become unpleasant, and some may be completely unrecognisable. For example, something like a bouquet of flowers might smell like rotten garbage to someone with parosmia.

The causes of both phantosmia and parosmia can be difficult to diagnose. Many cases are classed as idiopathic, meaning they have no known cause.

How to get rid of a bad smell in the nose

While the cause of a bad smell in your nose may take time to resolve, there are steps you can take to manage the discomfort.

Stay hydrated

Dehydration can make a stuffy nose worse. Make sure you drink plenty of fluids throughout the day, as this may help thin mucus and clear out the source of the odour.

Steam

Run some hot water in a sink, or pour it carefully into a heatproof bowl. Place a towel over your head and breathe in through your nasal passages to help shift mucus and reduce congestion.

Saltwater rinse

Rinsing your nose with a mixture of table salt, bicarbonate of soda and warm water can help get rid of a bad smell in the nose. Visit your local pharmacy for advice on how to do this safely. Some pharmacies even sell pre-made saltwater rinse packets and nasal cavity irrigation tools.

If you have new changes in smell or taste, it is important to see your doctor to work out the cause.