 Metallic Taste
Q: What does it mean when you have a "metal"
taste
in your mouth that is persistent?
A: There are many things that can distort one's sense of
taste. Change in our ability to taste can be a very unpleasant
sensation as well as a signal of other health concerns.
Taste is one of the five basic senses.Taste affects the
appetite, helping to ensure adequate nutrition. It also
protects us by letting us know to avoid eating contaminated,
rotten foods. And, combined with the sense of smell with
which it is intimately related, it can warn of smoke, noxious
fumes or simply bad quality air. So our sense of taste is
necessary for our survival and fitness as well as our happiness.
There are a number of things that can go wrong with taste
and smell. Drugs, trauma, cancer, infection, as well as
many neurological or metabolic diseases can reduce or eliminate
taste and smell. Alterations and distortions of the sense
of taste are called dysgeusias. Complaints of having a metallic
taste on the tongue are among the most common discriptions.
It can be most unpleasant, ruining the taste of food that
one might ordinarily relish, while also causing a nagging
bad taste throughout the day that does not go away with
eating, mouth washes or breath mints.
Persistent metallic taste sensations have been reported
by workers in brass foundries and among those who weld with
steel. Occasional patients with dentures, dental appliances,
and amalgam fillings will also report a metallic taste.
Certain drugs, most notably the antibiotic metronidazole,
but many others as well, may cause similar alterations in
taste.
The mechanism whereby taste is altered is often unclear.
At a cellular level, a series of events needs to occur in
order for you to normally process and interpret taste sensation.
Saliva carries and distributes the morsel in question to
taste cells that cover the surfaces of taste buds, which
are in turn arranged on papilla -- those bumpy things seen
on the tongue. There are different kinds of papilla that
are more or less grouped in different areas of the tongue.
The front of the tongue is used to detect sweet and salty
sensations, the sides pick up sour sensations and bitterness
is detected in the back of the tongue.
Once the tasted item hits the taste cell receptor, there
is a change in the cell membrane, causing a flux of ions
through the membrane and stimulation of nerve endings, which
in turn send signals to the brain for interpretation and
integration. A lesion or problem anywhere along this pathway
can muck things up. Therefore, inadequate saliva; the destruction
or coating of taste buds by infections, toxins or other
problems; and injuries to the nerves or brain all may cause
a reduced or abnormal perception of taste.
Sometimes the cause of a metallic taste cannot be found.
When you see your doctor, he or she will inspect the tongue
for loss of papilla, atrophy or a white/brown coating. Your
doctor will also check for evidence of nerve injuries or
weakness, infections of the sinuses or teeth, trauma to
the head or face, and a host of other possibilities, as
well as screen for diseases and drugs that may be associated
with taste disturbances. If all these are negative and no
explanation is found, we can hope that with time it will
go away of its own accord.
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