Why do I have a bad taste in my mouth even after brushing?

Brushing teeth does not clean the back of the tongue, the spaces between teeth, the tonsils or the sinuses. Add tongue cleaning and flossing. If the taste persists, look for a dry mouth, reflux, thrush or a medicine. Our guide to bad breath even after brushing covers the same gaps.

Can a bad taste in the mouth be a sign of illness?

Sometimes. Infections, reflux, diabetes, and liver or kidney disease can all change taste, though they usually come with other symptoms. A bad taste with weight loss, fatigue or feeling generally unwell is worth a doctor's visit.

How long does a bad taste from antibiotics last?

Taste changes from medicines usually fade after the course ends. Some antibiotics, such as metronidazole and clarithromycin, are well known for causing a metallic or bitter taste. Antibiotics can also trigger oral thrush, which causes its own unpleasant taste and needs treatment.

Does a tongue scraper help with a bad taste?

Often, yes, when the taste comes from coating on the tongue, which is one of the most common causes. It will not fix an abscess, thrush, reflux or a medicine side effect, so if a week of tongue cleaning makes no difference, look elsewhere.

Bad Taste in Mouth: Causes and How to Get Rid of It

Why do I have a bad taste in my mouth?

Written by Adèle & Dvir · 10 sources cited · Updated October 19, 2026

Quick answer

A bad taste in your mouth is most often caused by something in the mouth itself: plaque and a coated tongue, gum disease, a tooth infection, oral thrush or a dry mouth. Tonsil stones, postnasal drip, reflux, medicines and smoking are the next most common causes. Most cases clear with better cleaning and treating the cause, but a bad taste with fever, facial swelling, white patches or a sore lasting more than 3 weeks needs a professional.

What "bad taste" usually means

People use "bad taste" for a foul, stale, rotten or rancid taste that lingers no matter what they eat. The NIDCD uses almost the same words to describe dysgeusia: a foul, salty, rancid or metallic taste that persists. A bad taste and bad breath often travel together, because the same bacteria and debris cause both. If one particular taste stands out, our pages on metallic, bitter, sour and salty tastes go into more detail.

Causes, most to least common

Plaque and a coated tongue. Bacteria, food debris and dead cells collect on teeth and on the back of the tongue.
Gum disease. The NHS says it can lead to bad breath and a bad taste, along with bleeding, swollen gums.
Dry mouth. The NHS lists dehydration, medicines, mouth breathing at night, anxiety and cancer treatment as common causes.
Tooth infection or abscess. The NHS lists a bad taste with intense toothache, redness, swelling and sometimes a high temperature.
Oral thrush. The NHS lists an unpleasant taste, not tasting things properly, white patches and soreness.
Tonsil stones and postnasal drip. Cleveland Clinic lists a bad taste among tonsil stone symptoms and bad breath among postnasal drip symptoms.
Reflux. Stomach acid leaves a sour, unpleasant taste.
Medicines, smoking and colds, which change taste directly or by drying the mouth.

Finding your cause

Clue	Likely cause	Who to see
Thick white or yellow film on the back of the tongue	Tongue coating	Self-care first
Bleeding or swollen gums	Gum disease	Dentist
Throbbing tooth, swollen face or gum, fever	Abscess	Dentist urgently
White patches that wipe off to leave red, sore areas	Thrush	Pharmacist or doctor
Small white lumps at the back of the throat	Tonsil stones	Self-care or doctor
Heartburn, worse lying down	Reflux	Pharmacist or doctor

A one-week routine to get rid of a bad taste

Brush twice a day for two minutes, including the gum line.
Clean between teeth once a day with floss or interdental brushes.
Clean your tongue once a day, working from back to front. The NHS includes this in its self-help advice for bad breath. See how to use a tongue scraper.
Drink water through the day and chew sugar-free gum after meals.
Cut back on smoking and alcohol, both of which dry the mouth.

A note on evidence: a 2019 Cochrane review of bad-breath treatments found only two small trials (46 people) of tongue cleaning versus none and rated that evidence very low certainty; mouthwashes and other treatments fared little better, mostly because trials were small. That does not mean they do not work, only that the size of the benefit is uncertain. If a week of thorough cleaning does not help, the cause is probably not plaque or coating.

What a dentist or doctor can do

A dentist can remove tartar, treat gum disease and cavities, and drain or treat an abscess. A pharmacist or doctor can treat oral thrush with antifungal medicine and advise on reflux. If the mouth looks healthy, a doctor will look at medicines, sinuses and general health, and may refer you to an ear, nose and throat specialist for taste and smell testing.

When to see a dentist or doctor

A bad taste with toothache, facial or jaw swelling, or a high temperature - see a dentist urgently
Swelling that makes it hard to breathe, swallow, speak or open your mouth - call 911
White or red patches, an ulcer or a lump in the mouth lasting more than 3 weeks - see a dentist or doctor
Painful, bleeding or swollen gums - see a dentist
A bad taste that persists after a week or two of thorough cleaning - see a dentist

This guide is general information, not a diagnosis. If you are worried about a symptom, see a dentist or doctor.