Fungal diseases are infections caused by various fungi (yeasts or moulds) found in the environment. Fungi can cause simple, easy to treat infections such as vaginal candidiasis (yeast infection), thrush, and “athlete’s foot,” but they can also cause serious, life-threatening infections. Most fungi in the environment usually do not cause infection/disease in otherwise healthy people. However, these same fungi can cause severe illness in people who have a weakened immune system due to cancer, human immunodeficiency virus (HIV) infection, tuberculosis (TB) infection, or immune-suppressing medications. Fungal infections are a major public health concern in South Africa due to the high incidences of HIV infection, TB infection, and poverty. Fungal infections, also called mycoses, can be local, meaning they are confined to one area of the body, usually the skin, mouth, or vagina, or they can be systemic, meaning they affect one or more internal organs, such as the lungs, eyes, liver, and brain.
Local mycoses include fungal nail infections, ringworm, vaginal candidiasis, thrush (candida infection of the mouth, throat, and oesophagus), mycetoma, and sometimes mucormycosis and sporotrichosis.
Systemic mycoses include blastomycosis, cryptococcus gattii or cryptococcus neoformans infection, paracoccidiomycosis, coccidiomycosis (Valley Fever), histoplasmosis, aspergillosis, candida auris infection, invasive candidiasis, pneumocystis pneumonia (PCP), mucormycosis, talaromycosis, and sporotrichosis.
Most fungal infections will require treatment with antifungal medications (also called antimycotics). Antifungals are available as topical creams, ointments, drops and sprays, vaginal suppositories, oral pills and liquids, and intravenous (IV) medications. There are several classes of antifungal medications, and the type of medication depends on the type, severity, and location of the fungal disease.
Azole Antifungals work by stopping the production of a component of the fungal cell membrane to clear fungal infections. Examples of azoles used to treat systemic fungal infections include fluconazole, voriconazole, itraconazole, ketoconazole, and posaconazole. These medications are known to have several drug interactions, and some of these medications can treat more severe fungal infections than others. Topical azole antifungals are available for the treatment of fungal skin infections and vaginal yeast infections. Examples include clotrimazole, miconazole, ketoconazole, isoconazole, and tioconazole. Many topical antifungal medications are available over the counter without a prescription.
Polyenes work by forming holes in the wall of the fungal cell membrane, killing fungal cells in the body. Examples include amphotericin B, an IV medication, nystatin, a topical medication that is also used as an oral suspension for the treatment of thrush, and natamycin, an antifungal eye drop. Amphotericin B is available in two forms: amphotericin B deoxycholate, and liposomal amphotericin B. The liposomal form is preferred due to the severe side effects of amphotericin B deoxycholate.
Echinocandins work by stopping the formation of the cell wall in fungi. It is important to note that human/animal cells do not have a cell wall, so these drugs are generally well tolerated and less toxic than many other antifungal medications. Examples of echinocandins are micafungin, caspofungin, and anidulafungin. These are only available as IV medications.
Allylamines work by causing a deficiency of a component of the fungal cell membrane, therefore causing fungal cell death. An example is terbinafine, which is available as an oral and topical medication. Amorolfine is a similar medication that is only used as a topical treatment for fungal nail infections.
Flucytosine and Griseofulvin are antifungals that aren’t used often in practice anymore, due to fungal drug resistance and teratogenicity (birth defects). IV flucytosine may be used in addition to other medications, and griseofulvin is an oral option in difficult to treat fungal infections of the skin, nails, and hair shaft. It should not be used in pregnant women because of the risk of birth defects.
Common side effects associated with antifungal medications include:
Severe side effects, though rare, are discussed below. If you experience these symptoms while taking antifungal medications, you should seek medical attention right away.
Drug Interactions– Several antifungal medications, especially azoles, interact with many other drugs. Some interactions can cause serious side effects or significantly increase or decrease drug levels, which can cause toxic effects or cause medications to be ineffective. It is important that your health care provider is aware of all medications you are taking when prescribing antifungals.
Hepatitis/Liver Damage- Signs and symptoms include loss of appetite, abdominal pain and swelling, yellowing of the skin or whites of the eyes, nausea/vomiting, excessive tiredness or weakness, dark urine, or pale stool.
Kidney Failure- Signs and symptoms include decreased urine output, dark urine, and excessive tiredness/weakness. Some medications, particularly amphotericin B, are known to cause kidney failure, and providing extra IV fluids before and during therapy can help prevent it or lessen the severity.
Heart Issues- Some antifungals are known to rarely cause heart failure or abnormal heart rhythms. These may cause extreme tiredness and weakness, dizziness, shortness of breath, or palpitations.
Bone Marrow Suppression is a rare side effect of some antifungals. This results in abnormal blood cell counts, which can cause extreme weakness and tiredness, and abnormal bruising or easy bleeding.
Allergic Reactions are possible with any medication. Signs and symptoms include rash, hives, swelling in the tongue and throat, shortness of breath, wheezing, and nausea/vomiting. Blisters and peeling skin can be a sign of a very serious allergic reaction called Stevens-Johnson Syndrome.
There are no vaccines available that can help prevent fungal diseases. Good hygiene practices such as keeping the skin clean and dry, avoiding walking barefoot in public showers and locker rooms, and masking and wearing gloves when working in soil that can potentially contain fungal spores can prevent you from contracting some fungal infections, and these are especially important in people with suppressed immune systems. The use of antibacterial drugs (antibiotics) can cause overgrowth of fungi leading to fungal infection. It is important to take them exactly as prescribed and no longer than the recommended duration of therapy. When taking antifungal medications, especially long-term, it is important to follow up with your doctor regularly and have routine lab work done, which can usually detect serious side effects such as kidney/liver failure and bone marrow suppression. Patients with medical problems that weaken the immune system may need medication to help prevent fungal infections. There are many treatment options available for the treatment of fungal infections, and a pharmacist can help you select a topical medication for skin infections or vaginal yeast infections. If these do not clear the infection, it is best to seek medical advice for additional therapy.