Full examination with gum charting
We look at each tooth and filling, measure gum pockets, check for tenderness on tapping and take small X-rays where a hidden infection or leaking margin is suspected.
About this treatmentDental condition · Wimpole Street, Marylebone
A bad taste in the mouth: what your teeth and gums may be telling you
A lingering metallic, sour or foul taste is one of those symptoms people put up with for weeks, assuming it is something they ate. Quite often the mouth is trying to flag a problem: a filling that has started to leak, a gum pocket weeping slowly, a tooth whose nerve has died quietly, or saliva that has thinned because of a new tablet. Taste changes also have medical and medication causes, so part of our job is to work out which side of the line yours falls on. At Wimpole Street we begin with an unhurried look at every tooth, restoration and gum margin, and we tell you plainly whether we think the cause is dental.
Recognising it
How it usually feels
A taste that is strongest in one region of the mouth
Localised taste usually points to a specific tooth, filling or gum pocket.
Metallic or salty flavour, especially after brushing
Traces of blood from inflamed gums taste metallic.
A foul or rotten taste that comes and goes
Can indicate pus intermittently draining from an abscess or deep pocket.
Bad breath at the same time
The same bacteria that produce odour produce taste compounds.
Food catching around a particular tooth
Debris fermenting in a gap becomes sour within hours.
Dryness, stickiness or thick saliva
Low saliva flow concentrates whatever is in the mouth and alters taste perception.
Behind the symptoms
What's going on
- 01
Inflamed gums and periodontal pockets
Bleeding gum tissue releases small amounts of blood and inflammatory fluid, and the bacteria living in pockets generate sulphur and acid by-products. The result is a persistent metallic or bitter background that brushing only briefly interrupts.
- 02
A tooth infection draining into the mouth
When the nerve inside a tooth dies, or a pocket around a root becomes infected, pus can find a route out through the gum. It may be barely visible, yet the taste is unmistakable and often described as rotten. This pattern needs treating at source.
- 03
Decay or a leaking restoration
A cavity, or a filling or crown whose edge no longer seals, harbours food that ferments. The breakdown products are sour and the surrounding tooth may become sensitive. Older metal fillings can also contribute a faint metallic note when they corrode.
- 04
Food trapping between teeth
Where a contact point has opened up, or a tooth is tilted, fibrous food wedges in and decomposes. Most people can identify the spot with floss, and the smell on the floss confirms it.
- 05
Reduced saliva
Many antidepressants, blood-pressure tablets, antihistamines and inhalers reduce saliva. With less rinsing, bacterial products accumulate and taste buds receive a distorted signal. Dehydration and mouth breathing at night have the same effect.
- 06
Non-dental contributors
Acid reflux, sinus infections, some supplements, pregnancy, smoking and certain medical conditions all alter taste. If the mouth looks healthy we will say so and suggest your GP or pharmacist reviews these.
Before your appointment
What you can do today
- Floss or use interdental brushes between every tooth, paying attention to any spot where food routinely lodges, and note whether the taste improves afterwards.
- Sip water frequently and keep a glass by the bed; sugar-free gum or lozenges help if your mouth feels dry.
- Rinse with warm salt water after meals if a gum area feels tender, which is soothing though not a treatment.
- Avoid alcohol-based mouthwashes, which dry the mouth and can make a metallic taste worse.
- Review any recent changes to medicines or supplements with your pharmacist, but do not stop prescribed medication without advice.
These are holding measures, not a substitute for an examination. Use any pain relief exactly as directed on the pack and check with a pharmacist if you take other medicines.
In the chair
How we treat it at Wimpole Street
Hygiene and gum therapy
Cleaning above and below the gum line removes the bacterial load responsible for most persistent tastes; deeper pockets are treated under local anaesthetic over further visits.
About this treatmentReplacing leaking fillings or treating decay
A cavity or worn restoration is cleaned out and rebuilt in composite so it seals properly and no longer traps food.
About this treatmentRoot canal treatment or extraction
Where a dead or infected nerve is the source, the tooth is either root-treated and later crowned, or removed if it cannot be saved. Either way the draining infection stops.
About this treatmentFees
Costs to expect
An examination at Wimpole Street is planned at £95 and a hygiene visit from £89, which together resolve the majority of taste complaints that are gum-related. New patients will be able to book an initial check-up at a reduced fee once the diary opens.
If a tooth needs restoring, white fillings start from £185. Root canal treatment is indicative at £695 for a front tooth and £895 for a molar, and a crown to protect the tooth afterwards is from £995. An extraction, where that is the better option, starts from £250. Nothing proceeds until you have the plan and fees in writing.
Figures are indicative prices for Wimpole Street and are confirmed in a written plan once a dentist has examined you. Fees match our South Kensington and St Paul's clinics.
Don't wait if
When to see a dentist
- The taste has lasted more than a fortnight and does not clear with careful cleaning.
- You notice a swelling, a small pimple-like spot on the gum or tenderness on one tooth.
- Your gums bleed when brushing or you can taste blood without an obvious cause.
- A filling, crown or other recent dental work is where the taste seems to originate.
- You feel feverish or unwell alongside the taste, which may indicate spreading infection.
- Your mouth has become noticeably drier over recent weeks.
FAQ
Common questions
Brushing removes plaque from the outer surfaces but not from between teeth, under the gum edge or from within a cavity or leaking filling. If bacteria or pus are being produced somewhere your brush cannot reach, the taste will keep returning until that source is dealt with professionally.
It is possible. Older amalgam fillings can corrode at the margins, and a metal crown against an amalgam filling occasionally produces a mild galvanic taste. More commonly, though, a metallic taste comes from bleeding gums. An examination distinguishes the two.
Not always, but it is the possibility we rule out first. Food fermenting in a deep cavity or under a loose crown can taste similar. If the tooth is tender to tap, there is a spot on the gum or an X-ray shows a shadow at the root, infection is the likely cause and needs treatment rather than antibiotics alone.
Then the cause is probably not dental. Reflux, sinus problems, medication side effects, zinc deficiency and neurological causes can all alter taste. We will explain what we have excluded so your GP can pick up the thread without repeating work.
Yes. Saliva dissolves flavour molecules and carries them to taste buds, and it constantly rinses away bacterial by-products. When flow drops, tastes become distorted and bacterial compounds concentrate. Addressing the dryness, where possible, often improves the taste as well.
Marylebone, W1
Wimpole Street opens 1 October 2026
Leave your details and we will be in touch when the Marylebone diary opens. If the problem cannot wait, the same clinicians are already seeing patients in South Kensington and at St Paul's.
Related conditions
Opening 1 October 2026
Wimpole Street is not yet seeing patients. Until then, please book or call our South Kensington clinic on 020 7183 2362 or our St Paul's clinic on 020 7183 3709. Questions about the new clinic: wimpolestreet@md.co.uk.
Until we open
Need an appointment before 1 October 2026?
The same clinical team already works from two other Medical & Dental clinics. Book at either one now and, if you prefer, move your ongoing care to Wimpole Street once the doors open.
South Kensington
- 20 Old Brompton Road, London SW7 3DL
- Open seven days a week
- 020 7183 2362
St Paul's, City of London
- 5 Ave Maria Lane, London EC4M 7AQ
- Open Monday to Friday
- 020 7183 3709
