Antivirals & Skin Conditions

Reviewed By:
Mary Ellen Luchetti, M.D., AAD

Summary

Antiviral agents are medications designed to combat viral infections. A virus is a tiny infectious organism that invades cells and forces them to replicate the virus. These new viruses then go out and attack other cells, including skin cells. Antivirals can be used to treat existing infections or to prevent a person from becoming infected with a virus.

Most viruses that cause skin infections can be divided into several major groups, including human herpesvirus (HHV), which includes herpes simplex virus (HSV) and herpes zoster virus; human immunodeficiency virus (HIV) and human papillomavirus (HPV). These viruses cause disorders such as warts, cold sores, chicken pox and shingles. The HIV virus can lead to AIDS.

Chickenpox virus is highly contagious, causing an itchy rash, and can occur in children or adults.

Viruses that infect the skin can be difficult to treat. However, in recent years, the U.S. Food and Drug Administration (FDA) has approved both systemic and topical antiviral medications designed to kill viral infections. Research continues on new and more powerful versions of these drugs.

About antiviral agents

Antiviral agents are medications designed to combat viral infections. Such infections can attack many parts of the body, including a person’s skin.

A virus is a tiny infectious organism that enters the body and invades living cells. Once inside the cell, the virus releases its deoxyribonucleic acid (DNA) or ribonucleic acid (RNA) into the cell. The DNA or RNA contains the genetic code that takes control of the cell and causes it to replicate the virus. These replications then go on to infect other cells and repeat the process.

There are several types of viruses that infect the skin and cause symptoms. In many cases, viral skin conditions can be difficult to treat. Not only is it difficult to target viruses, but the virus itself can become immune to a medication over time.

In recent years, the U.S. Food and Drug Administration (FDA) has approved numerous antiviral agents designed to kill viral infections. These medications interfere with a virus’ ability to replicate and spread. Research continues on new and more powerful versions of these drugs.

Individuals may take antivirals to treat an existing viral infection or to prevent the contraction of a virus. Patients who use antiviral agents should closely follow their physician’s recommendations on how to properly take the treatment. In some cases, patients stop taking their medication because the skin appears to have cleared. However, the infection may remain active and is more likely to worsen in patients who stop treatments before they are complete.

Types and differences of antiviral agents

There are several different kinds of antiviral agents that are prescribed to fight viral skin infections. These medications can be divided into systemic antivirals and topical antivirals.

Systemic antivirals are usually given orally in pill form. However, they sometimes may be administered intravenously (into a vein). This is most likely in situations where the patient is suffering from a suppressed immune system (due to HIV infection, organ transplantation or another condition), is unable to swallow oral medication, has impaired memory or mental capacity or does not have quick access to a hospital should complications arise during drug therapy.

Systemic Antivirals
Generic Name	Brand Name(s)
acyclovir	Zovirax
famciclovir	Famvir
valacyclovir	Valtrex

Topical antivirals are usually available in various forms, including creams, ointments, gels, patches and sprays. In addition, most topical antivirals can be further subdivided into one of three major classes:

Cytodestructive drugs (destroys infected tissue)
Immunoenhancing drugs (enhances immune system)
Viricidal drugs (destroys viruses)

Topical Antivirals
	Generic Name	Brand Name(s)
Cytodestructive	bleomycin	Blenoxane
	cantharidin	Canthacur
	podofilox	Condylox
	salicylic acid	multiple
	s-fluorouracil	Efudex, Fluoroplex
Immunoenhancing	imiquimod	Aldara
Viricidal	acyclovir	Zovirax
	cidofovir	Forvade
	foscarnet	Foscavir
	idoxuridine	Stoxil, Dendrid
	penciclovir	Denavir

Conditions treated with antiviral agents

Most viruses that cause skin infections can be divided into several major groups. These include:

Human herpesvirus (HHV). This family of viruses includes strands of the herpes simplex virus that cause cold sores (herpes simplex virus type 1) and genital lesions (herpes simplex virus type 2), and the herpes zoster virus that causes chickenpox and shingles. Human herpesviruses 6 and 7 cause a childhood illness called roseola infantum that can cause high fever and rash. Systemic antiviral agents are typically used to treat HHV.
Human papillomavirus (HPV). A group of viruses that cause various types of warts (papillomas). These include common warts, foot warts, flat warts, genital warts and filiform warts. Some types of warts require no treatment, whereas others may need treatment with topical or systemic antiviral agents.
Poxvirus. A group of viruses that include cowpox, monkeypox, and smallpox. One of the most destructive viral infections, smallpox has been eradicated throughout the world. Since 1978, only isolated, laboratory-acquired forms of the disease have been reported. It is usually treated with a vaccine that is effective up to four days after exposure, although the drug cidofovir has shown promise in the laboratory as a potential treatment.
Human immunodeficiency virus (HIV). HIV is the virus that causes acquired immune deficiency syndrome (AIDS). Skin lesions that appear as a result of this infection are often the first sign that the patient has HIV. These lesions often result from a separate infection with HHV, papillomavirus or other infectious agents. Systemic antiviral agents are typically used to treat HIV. Numerous other medications are available that specifically treat HIV.

Conditions of concern with antiviral agents

Antiviral agents should not be given to patients who have experienced hypersensitivity to the drug in the past. There are few other contraindications associated with other conditions. However, patients with neurological, liver or kidney problems should use antiviral agents with caution. Patients should closely consult with their physician about whether certain conditions preclude taking specific antiviral agents.

Potential side effects of antiviral agents

Patients who use topical antivirals rarely experience side effects. However, side effects that may occur in rare circumstances include burning and stinging, headache, itching (pruritus), mild pain, nausea, skin symptoms such as rash or flaking, and inflammation of the vulva (vulvitis).

Most patients who take systemic antivirals to treat conditions other than human immunodeficiency virus (HIV) do not experience side effects. However, in some patients, systemic antivirals may cause symptoms such as diarrhea, headache, nausea and vomiting. Patients who receive these medications intravenously may also experience inflammation of a vein (phlebitis) and inflammation at the insertion site. Intravenous administration can also result in impairment of the kidneys that may be reversed upon cessation of using the drug.

Systemic antivirals used to treat HIV may cause side effects such as anorexia (loss of appetite), diarrhea, fever, headache, insomnia, gastrointestinal pain, malaise (general ill feeling), myalgia (muscular pain or tenderness), rash, sleeplessness and nausea. In addition, some patients may experience more significant side effects such as bone marrow suppression, hepatic (liver) toxicity, pruritus, pancreatitis (inflammation of the pancreas), oral and esophageal ulcers, cardiomyopathy (disease or disorder of the heart muscle) or peripheral neuropathy (degenerative state of the peripheral nerves).

Drug or other interactions with antiviral agents

Patients should consult their physician before taking any additional prescriptions, over-the-counter medications, nutritional supplements or herbal medications. Of particular concern to individuals using antiviral agents are:

Cimetidine (used to treat gastrointestinal disorders)
Probenecid (used to treat chronic gout or gouty arthritis)
Theophylline (used to treat lung problems resulting from various disorders)

Pregnancy use issues with antiviral agents

The U.S. Food and Drug Administration (FDA) has classified most antiviral agents as belonging in either category B (which means that either animal studies have shown no risk to an animal fetus, or human studies have shown no risk to a human fetus) or category C (which means animal studies have shown a risk to animal fetuses, but risk has not been adequately studied in humans).

Patients should discuss the potential risks and benefits of using antiviral agents during pregnancy and breastfeeding with their physicians.

Questions for your doctor on antiviral agents

Preparing questions in advance can help patients to have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following questions related to antiviral agents:

Are antiviral agents safe for me to take?
How and when should I take this drug?
What should I do f I miss a dose?
What side effects may I develop?
For what side effects should I seek medical attention?
How long will it be before the drug starts taking effect?
If my condition clears quickly, can I stop taking the antivirals?
Are there medications, nutritional supplements or herbal medications I should avoid while taking this drug?
How will I know if the drug is working?
What are other possible treatments if the drug does not work?