Microorganisms such as viruses, bacteria and fungi are everywhere,
including in and on your body. More than 200 species of bacteria live in
your mouth, in your digestive and respiratory tracts and on your skin.
In general, the relationship between you and this array of microbes is
mutually beneficial. You provide nutrition, protection and
transportation for them, while they stimulate your immune system,
synthesize essential vitamins and help protect against harmful viruses
But your relationship to microorganisms in the world at large is more
complex. Some microbes are highly beneficial, but others such as those
that cause malaria and meningitis can be deadly. For that reason, your
immune system works to repel harmful invading organisms while
maintaining a balance between "good" and "bad" microbes that normally
inhabit your body.
But sometimes these protective mechanisms fail. Oral thrush and other
Candida infections occur when your immune system is weakened by disease
or drugs such as prednisone or other corticosteroids, or when
antibiotics disturb the natural balance of microorganisms in your body.
These illnesses may make you more susceptible to oral thrush infection:
Usually affecting children younger than age 3, this group of rare
disorders is marked by a chronic Candida infection of the mouth and
fingernails as well as skin on the scalp, trunk, hands and feet.
Scaly, crusted lumps known as granulomas also may develop in the
mouth or on the nails and skin. Adults occasionally develop the
disorder usually as a result of a tumor on the thymus gland (thyoma).
The human immunodeficiency virus (HIV) the virus that causes AIDS
damages or destroys the cells of your immune system, making you
more susceptible to opportunistic infections your body would
normally resist. One of these opportunistic infections is oral
thrush. Thrush is rare in the early stage of AIDS, usually appearing
only when counts of helper T cells one of the key cells in your
immune system fall below 350. Although oral thrush is the least
serious of the fungal infections that can affect people with HIV, it
may be an indication that HIV is worsening. Candida esophagitis,
which occurs when thrush spreads to the esophagus, generally
develops when T cell counts are 200 or less and is considered an
AIDS-defining illness an opportunistic illness that indicates a
person with HIV is developing AIDS.
If you're dealing with cancer, your immune system is likely to be
weakened both from the disease and from treatments such as
chemotherapy and radiation. A weakened immune system increases the
chances you may develop Candida infections such as thrush.
If you don't know you have diabetes or the disease isn't well
controlled, your saliva may contain large amounts of sugar. This can
encourage the growth of Candida.
Vaginal yeast infections are caused by Candida albicans the
same fungus that causes oral thrush. Although a yeast infection
isn't dangerous, a pregnant woman can pass the fungus to her baby
during delivery. As a result, her newborn may develop oral thrush
within the first several weeks after birth.
Dry mouth (xerostomia).
This occurs when the salivary glands in your mouth don't produce
enough moisture. Dry mouth disrupts the balance of normal
microorganisms in your mouth, increasing your risk of oral thrush.
Although not itself a disease, dry mouth can be a symptom of certain
illnesses, including Sjogren's syndrome an autoimmune disease that
causes an extremely dry mouth and eyes. Bone marrow transplants,
stress or anxiety, depression, and certain nutritional deficiencies
also can cause a dry mouth. So can chemotherapy, radiation to the
head and neck area and hundreds of medications especially
antidepressants, pain and high blood pressure drugs, tranquilizers,
diuretics and antihistamines.
Certain lifestyle factors also can make you more likely to develop oral
hyperplastic candidiasis is a type of thrush that occurs in people
who smoke. It causes creamy white patches on the insides of the
cheeks and tongue, along with persistent nodules or lumps.
Red patches also may sometimes appear, which can be a sign that
cancerous changes are occurring in the cells.
People who wear dentures especially if they don't
fit properly sometimes develop a type of thrush marked by redness
Anyone can develop oral thrush, but the infection is especially common
in infants and toddlers whose immune systems aren't yet fully developed.
In addition, babies can pass the infection to their mothers during
You're also more likely to develop oral thrush if you: