Fungal Infections

Fungi are everywhere — as molds, they grow in homes and on foods; as yeasts, they are found in foods and in our bodies. Even mushrooms are classified as fungi, although most of them are quite harmless. Whatever form fungi take, they survive by breaking down organic matter. Only 180 of the 250,000 known species of fungi can cause disease in people.

Many different kinds of fungi live inside the human body in peaceful balance with it. When your body’s immune system is weakened due to an illness such as AIDS or treatment such as chemotherapy, the balance can be disturbed, allowing fungi to cause disease. Such diseases are called opportunistic infections.

An opportunistic infection is caused by an organism that normally lives in our body or our environment without doing any damage, but it takes advantage of the opportunity a weakened immune system gives it to cause disease.

People most often come into contact with fungi in their natural habitats. Because many fungi live in the ground, gardeners are often at risk for fungal infections. The organisms can enter the body through bare feet, hands or other exposed areas. Different kinds of fungi live in different geographic areas.


Symptoms of fungal infections differ depending on the type and severity of the infection, the area of the body affected, and individual factors.

Following are symptoms of some fungal infections:

  • Athlete’s foot: Itching of the feet; scaling and flaking of the skin of the feet; thick, yellowish toenails that detach from the nail beds if the fungus infects the toenails.
  • Jock itch: Itching of the groin area; red, scaly rash in the groin area (most often occurs in men).
  • Ringworm: Red, itchy area on the scalp, often in the shape of a ring; hair loss in the affected area.
  • Fungal infections that affect the mouth (oral thrush): Lesions or sores that are raised, are yellow-white in color, and appear in patches in the mouth or throat and/or on the tongue; sore, bleeding gums; patches or lesions that become sore, raw and painful, making it difficult to eat or swallow.
  • Fungal infections that affect the vagina (vaginal thrush): Thick, white vaginal discharge, vaginal irritation, vaginal itching, burning with urination.
  • Fungal infections that affect the digestive tract (fungal gastroenteritis): Diarrhea, nausea and vomiting.

Recurrent fungal infections can be a symptom of a more serious condition, such as HIV/AIDS or diabetes. It is important to seek prompt medical care for repeated fungal infections, such as repeated vaginal yeast infections or oral thrush.


Antifungal drugs work by inhibiting the growth of a particular chemical in the cell membrane of fungi. Because this chemical is different from chemicals in the human cell wall, the antifungal drugs attack only the invading fungi, leaving your body’s own cells intact. Other drugs used against fungi inhibit DNA and RNA replication, preventing the cells from multiplying.

The most widely used antifungal drug, amphotericin B, is considered the gold standard because it is able to kill many different types of fungi. In the United States, this drug is only available intravenously.

Another class of drugs, called azoles, prevents new cell growth, but doesn’t kill fungal cells that are already there. Most of the azoles can be used topically and are common ingredients in Mycelex® and Monistat®, used to treat yeast infections.