Bad taste in the mouth is a common problem and may be perceived as lingering and unpleasant. It can decrease appetite and the ability to relish food, and also be quite distressing throughout the day. There may be a persistent salty, metallic, foul or acidic taste perceived in the mouth (dysgeusia or parageusia). Sometimes there may be a reduction (hypogeusia) or loss (ageusia) of the 4 main tastes – sweet, salt, sour and bitter. This can also be accompanied by a loss of smell. Rarely a burning sensation may be felt throughout the mouth (burning mouth syndrome).
In case of any of these symptoms, the common causes below should be looked for.
Poor Dental and Mouth Hygiene due to improper and inadequate brushing, or not rinsing the mouth after meals.
Tooth problems like loose teeth, ill-fitting dentures, plaque, and cavities, or a new incoming tooth.
Infections in the mouth include gingivitis and periodontitis (gum infections), tooth abscesses, mouth ulcers, and thrush (fungal infection causing white curd-like spots). In such cases, other signs like redness, swelling, bad breath (halitosis), sensitivity and pain may be coexistent with the bad taste.
Dry mouth (also called Xerostomia) can cause an unpleasant taste along with a dry sticky feeling. Inadequate saliva can increase bacterial growth in the mouth which can leave a bad taste. Dry mouth is common in the elderly. It can also occur due to tobacco chewing/smoking, tendency for mouth breathing, dehydration (or inadequate water intake) and co-morbidities like diabetes, hypothyroidism or autoimmune disorders. Other causes can include certain medicines (see below), nerve damage (trauma/extraction/surgical/stroke) or hormonal imbalance (during pregnancy or menopause).
Oral cancers or precancerous lesions should be ruled out in elderly people especially with a history of tobacco use.
EAR, NOSE, THROAT
Respiratory tract infections like the common cold, flu, sinusitis, tonsillitis, pharyngitis (throat infection) or ear infections can be the causative factor. There may be accompanying symptoms like stuffy nose, decrease in smell, sore throat, cough, phlegm (mucus), earache or pain while swallowing. Fever or body ache may also be present in some cases. These infections can be viral or bacterial in nature. The bad/unpleasant taste in the mouth is usually produced due to dry mouth resulting from mouth breathing due to a stuffy nose, or mucus in the mouth and on the tongue coming from the nose or throat. A decreased sense of smell and/or taste can be a symptom of COVID.
Non-infectious conditions like nose allergies (allergic rhinitis), nasal polyps (outgrowths) or deviated nasal septum can cause a chronic stuffy nose, increased mouth breathing and dry mouth. This can affect both taste and smell. Sleep apnea and snoring also increase mouth breathing and become contributing factors to dry mouth and unpleasant taste.
Acidity due to reflux of acid from the stomach (GERD- Gastro-Esophageal Reflux Disease) can cause an acidic or unpleasant taste in the mouth. Symptoms of acidity like heartburn, nausea, hoarseness/dry cough or abdominal pain are usually present.
Indigestion, Malabsorption, and altered Gut flora (useful bacteria found in our gut which help with nutrition and digestion) as seen due to unhealthy diet, gut infections, stress, too much consumption of alcohol or acidic drinks, bowel disorders (like IBS, IBD), liver dysfunction (hepatitis or cirrhosis), or antibiotic use, may also be a cause for bad/unpleasant taste in the mouth. There may be accompanying symptoms like gas, bloating, nausea, abdominal pain and constipation.
Nutritional Deficiencies like those of vitamin B group (B1, B2, B3, B6, folic acid-B9 and B12), vitamin A, iron (causes anemia) and zinc can also be a contributing cause.
Reaction to food ingredients like specific flavoring, additives or fragrances can also cause a lingering unpleasant taste.
MEDICINES AND SUPPLEMENTS
Certain medicines cause significant dry mouth or unpleasant taste. These can include:
- Antihistamines (given for cold, allergies and itching)
- Mucolytics and Decongestants (given in cold-cough)
- Inhalers and Nasal Sprays
- Antidepressants and Antianxiety drugs
- Sedatives and Antiepileptics
- Some BP lowering and anti-diabetic medicines
- Medicines for Pain and Inflammation
- Antispasmodics and drugs for nausea-vomiting
- Antirheumatic and Anti-gout drugs
- Anti-thyroid medicines
- Anti-acne drug (isotretinoin)
- Oral contraceptives
- Drugs for Parkinson’s/Alzheimer’s disease,
- Cancer radiation and chemotherapy.
- Mineral supplements containing higher amounts of metals like iron, calcium, magnesium, zinc, chromium, copper or selenium
The above list would suggest that almost any medicine can be a cause of persistently bad or disturbed taste! However, the medicine and its side effect of dry mouth or unpleasant taste may vary from person to person, and also depend on the dose, frequency and duration of use, as well as co-existing risk factors. So, a detailed history and clinical examination are important to zero in on this diagnosis.
Neurological causes like Dementia, Alzheimer’s, Parkinson’s disease, Multiple Sclerosis or after a Stroke (Cerebrovascular Accident -CVA) may be present especially in the elderly. Head injury, brain infection, epilepsy or a brain tumor can also affect the taste. In such cases history and presence of other neurological symptoms may offer a clue to the diagnosis.
Chronic exposure to heavy metals like lead and mercury, or chemicals like Pesticides and Insecticides can also leave a lingering unpleasant taste in the mouth.
TACKLING THE PROBLEM
Meticulous dental and oral hygiene with regular and proper brushing, along with rinsing the mouth after meals is the first step. Additional tongue cleaning, flossing and using an anti-bacterial mouth wash for rinsing can also be helpful in improving oral hygiene and removing unpleasant tastes.
In case of persistent bad taste, a thorough dental examination followed by a consultation with a physician to evaluate the various causes elaborated above, is recommended. A detailed history of all symptoms, associated conditions and medicines being taken, along with a general clinical examination are usually performed. Blood tests for hemoglobin and blood counts, sugar, Iron and vitamin B12 levels, liver, kidney and thyroid function may be ordered. Where required, imaging tests and neurological consults may also be conducted. The cause can be identified in most cases which is then appropriately and specifically managed, and usually leads to resolution of the taste problems.
Sometimes no specific cause may be identifiable especially in the elderly. Also, medicines being taken are often pertinent to disease control and therefore cannot be stopped or substituted. For dryness of mouth causing unpleasant taste, moisturizing mouth sprays and gels with ingredients like methylcellulose, glycerin, and xylitol/sorbitol are available. For unpleasant taste or breath, sugar-free chewing gums, mints and lozenges can give relief. Counselling, improving water intake, and increasing the variety and nutritive value of cooked dishes, food items and beverages can be helpful. Empirical therapies with vitamin-mineral supplements, antacids, probiotics, and digestive or appetite stimulants, are sometimes prescribed with variable benefit.
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