What causes anosmia?

You can be born with anosmia, but there are many things that can cause it throughout life. These include:

• head and nose injuries
• brain tumours and nasal polyps
• viral infections such as hepatitis, influenza or COVID-19
• some chemicals
• some medications
• surgery
• liver or kidney failure
• vitamin B12 deficiency
• hay fever (allergic rhinitis)
• bronchial asthma
• diseases including Parkinson's disease, multiple sclerosis or Alzheimer's disease
• chronic sinusitis
• cocaine addiction

Some people never find out what caused them to lose their sense of smell.

If you have a cold or flu, your sense of smell will usually come back within a week or 2. Otherwise, it's a unpredictable — in some cases, anosmia can be permanent.

If a person has a partial sense of smell, it's called hyposmia. Many things — including smoking, a cold or flu, depression, schizophrenia, seasonal affective disorder and ageing — can cause hyposmia.

How anosmia affects you

Obviously, if you have anosmia, you can't smell anything. But because the sense of smell is so closely connected to the sense of taste, you may find that food tastes bland. This can really affect your enjoyment of life, particularly if your social and family life revolves around meals. It can also make it hard for you to be bothered to eat and drink.

You might fear that you won't be able to notice a dangerous smell, like gas or smoke. You might worry about eating something that's spoiled. Some people living with anosmia can feel depressed.

See a doctor if you lose your sense of smell. If you feel depressed, speak to your doctor or call Beyond Blue on 1300 22 4636.

Anosmia diagnosis

Your doctor might refer you to an ear, nose and throat specialist. Tell the specialist when and how you think you lost your sense of smell.

The specialist might examine you nose with a medical instrument called an endoscope and ask you to identify different tastes and smells with a test kit. They might ask you to have a computed tomography (CT) scan or a magnetic image resonance (MRI) scan, or have a blood test.

Anosmia treatment

Treatment depends on why you lost your sense of smell. It can involve:

• nasal sprays and steroid pills
• antihistamines
• antibiotics
• an operation, e.g. to remove nasal polyps
• reducing your exposure to chemicals and other causes

You might get your sense of smell back without treatment, although it might take several weeks or months. Sometimes there is no treatment available.

Anosmia prevention

Avoiding certain chemicals, certain drugs, and not smoking might help prevent you losing your sense of smell.

Also, since anosmia can be one result of sustaining a brain injury, it's yet one more reason to be extra careful when playing dangerous sports, driving, or taking part in similar risky activities.

If you do have anosmia, you can make your environment safer by:

• making sure your smoke alarms are working
• checking that cookers, barbecues and electrical appliances are turned off properly
• reading food expiry dates carefully

Where to get help

• Use healthdirect's Symptom Checker to decide what to do next.
• Find a doctor near you here.
• Beyond Blue provides advice and support to people with depression. Call 1300 22 4636.
• Fifth Sense (UK) offer information about anosmia.