What is a fungal nail infection?
infections (onychomycosis) occur when
fungi invade a fingernail or toenail (nail plate) and
the skin underneath the nail (nail bed). Toenails are more commonly affected
than fingernails, because they grow very slowly, allowing the fungi more time
to develop. Toenails also require longer treatment time than fingernails
The infecting fungi may be a dermatophyte, yeast, or mold.
Dermatophytes cause about 90% of all fungal nail infections.3 Dermatophyte and mold infections can cause discomfort but are
usually not painful. Yeast infections, especially in the fingernails, can be
You can get a fungal nail infection when you come in
contact with the fungi and they begin to grow on or under your nail plate. You
can also get an infection by direct contact with an infected person or through
contact with floors, shoes, or other personal items, such as nail clippers or
nail files, that have fungi on them. Long-standing
athlete's foot also can result in fungal toenail
infection. Shoes that are moist, tight, and do not allow moisture to escape
contribute to fungal infections.
Why should I treat a fungal nail infection with oral medicine?
A fungal nail infection does not go away on its own and
tends to slowly get worse over time. An infection may spread into the nail root
(matrix), where new nail growth begins, and may spread to other nails. The
longer an infection is present and the worse it becomes, the harder it is to
treat. Severe, extensive infections, especially in older people who have had
the condition for many years, can cause very thick nails that are difficult to
trim and may cause pain or discomfort when walking. After this happens, it is
difficult to cure a fungal infection, even with oral medicines.
Your doctor may recommend treatment if you have a painful fungal nail
infection or a medical condition, such as
diabetes, that can lead to complications from foot
Why wouldn't I treat a fungal nail infection with oral medicine?
A fungal nail infection is not usually considered a
"must treat" medical condition. Some people decide not to treat a fungal
infection until it is uncomfortable or painful.
infections are difficult to treat, and the medicine is expensive. There is no
guarantee that oral medicine will work or that the fungal infection will not
come back. Of people successfully treated with antifungal pills, 15% to 20%
develop another infection in the next year.2 Advanced
age (older than 60) decreases the likelihood of a cure to about 65%.4
The medicine used for fungal nail infections can
cause serious side effects, including liver damage and heart failure.
Other treatment methods are also available, such as using an antifungal
cream or solution or removal of the nail, either surgically or nonsurgically.
How effective are the oral medicines available to treat fungal nail infections?
Terbinafine (Lamisil) is a first-line medicine
for fungal nail infections caused by dermatophytes.5
Research on oral terbinafine reports that in people with an infection caused by
- Killed fungi in 40% to 90% of the people using it.
- Killed fungi and produced a normal-looking nail in 35% to 50%
of the people using it.
- Was more effective than itraconazole, griseofulvin, or
Itraconazole is a preferred medicine for infections
caused by molds and yeast (Candida).5 It can also be used for dermatophytes. Research reports that
it killed fungi in 45% to 70% of people using it and produced a normal-looking
nail in 35% to 80% of the people using it.5
Fluconazole (Diflucan) has not been well studied for fungal nail
infections. But research is promising, and it is considered a first-line
therapy for infections caused by Candida.5 Oral fluconazole improved
the appearance of more than 75% of a toenail in 72% to 89% of people using
it.5 When taken in high doses once a week over 3
months for fingernail infection, oral fluconazole produced a normal-looking
fingernail in 90% of people using it and killed the fungi in nearly all the
people using it.5
and griseofulvin (Grifulvin V) are rarely used. Griseofulvin has low cure rates
and is no longer considered standard treatment for fungal toenail
What are the side effects of these medicines?
Rare but serious risks of
oral antifungals include serious drug interactions,
liver damage, liver failure, and
heart failure. Minor side effects of these medicines
include headache, stomach upset, diarrhea, rash, itch, and loss of taste
What are the risks of not taking these medicines?
If you are healthy, no serious medical risks are linked to ongoing fungal
infection. But the nail may eventually become deformed and thickened, resulting
in pain when wearing shoes or walking. You may consider your nail's appearance
If you have
diabetes or a weakened
immune system, a fungal infection can lead to a more
serious bacterial infection.
If you need more information, see the topic
Fungal Nail Infections.