Pharmacy Times

Antiviral Medications to Treat and Prevent Herpes

Author: Carrie DeKorte, PharmD, BCPS

Not all herpes infections are the same. Herpes zoster (shingles) is an infection caused by the varicella-zoster virus, which is the virus that causes chickenpox. Genital herpes is an infection caused by the herpes simplex virus (HSV). Medications can help decrease the severity of the herpes lesions and prevent recurrences, but they do not cure the infection. The dose of the medication is different, depending on which herpes virus is being treated, and whether the medication is for an initial episode or a recurrent episode or chronic treatment to prevent outbreaks.

Herpes Zoster

After an attack of chickenpox, the virus stays in the nerve cells. It is called a dormant infection. Anyone who has had chickenpox carries the virus. Shingles is more common in people with immune systems that are weakened from HIV infection, chemotherapy or radiation treatment, transplant operations, or stress. A stress on the body may allow the virus to become active and produce an "outbreak," causing a painful rash or blisters.

Herpes Simplex Virus

There are 2 types of herpes simplex virus. HSV-1 most commonly infects the lips and produces what is often referred to as "cold sores"or "fever blisters," but it also can cause genital herpes. HSV-2 is the usual cause of genital herpes, but it also can infect the mouth. HSV remains in the infected nerve cell of the body for life and can produce symptoms off and on.

What Medications Are Used to Treat and Prevent Herpes?

The first antiviral medication used to treat herpes was acyclovir. Acyclovir tablets and capsules are available in a generic form and therefore are less expensive, but they must be taken frequently throughout the day.

Acyclovir also is available as a liquid for people who have trouble swallowing, as eyedrops for eye infections, as an injection for severe life-threatening infections, and topically as a cream 5% or an ointment 5%. Famciclovir and valacyclovir tablets are as effective as acyclovir, are slightly more expensive, and are taken less frequently throughout the day (Table).

How Should Patients Use the Medications?

Patients should begin to take a medication immediately and take it exactly as directed, even if they are feeling better. Although the medication will not cure the herpes infection, patients should take the full course in order to prevent resistance to the medication. The medication also may help to prevent a recurrent infection.

If patients miss a dose, they should take the missed dose as soon as possible. If, however, it is time for the next dose, they should skip the missed dose and return to their regular schedule.

In fighting an infection, it is important to drink plenty of water, because these medications go through the kidneys. The recommended amount is 8 full glasses of water each day, but some people may need more. Patients should take their medication with a full glass of water. They may take it with food if it upsets the stomach otherwise.

The tablets, capsules, or oral liquid should be kept at room temperature, away from heat, light, and moisture. All medications should be kept out of the reach of children.

If using the acyclovir topical cream 5% or ointment 5%, patients should be sure to wash their hands before and after they apply the product. They should apply a thin layer to the affected area and rub gently. The use of gloves will help prevent the spread of the infection. Acyclovir cream 5% or ointment 5% should not be placed in the eyes?these products are for external use only. These products should be stored at room temperature, away from heat and light. If using the acyclovir eyedrops, patients should be sure to wash their hands before and after use.

What Should Patients Expect from Taking the Medications?

Whenever taking a new medication, it is important to be aware of signs of a life-threatening reaction. These signs include wheezing; chest tightness; fever; itching; a bad cough; a blue skin color; fits; or swelling of the face, lips, tongue, or throat. Anyone who develops these signs should seek medical attention immediately.

While taking antiviral medications, patients may get sunburned more easily. They should avoid sun, sunlamps, and tanning beds. They should use sunscreen and wear protective clothing and eyewear.

Some people develop headaches from antiviral medications, and these headaches usually are mild and self-limiting. Mild pain medicine may help. Anyone who develops a sudden or severe headache should seek medical attention immediately.

Antiviral medications may cause nausea or vomiting. Small frequent meals, frequent mouth care, sucking on hard candy, or chewing gum may help. If the nausea or vomiting becomes severe, patients should contact their health care provider.

About 1% to 10% of people may experience lightheadedness, dizziness, or headache. If the symptoms become severe, patients should seek medical attention immediately.

If using the acyclovir topical cream 5% or ointment 5%, patients may experience some local irritation, such as mild pain, itching, or stinging. If the irritation is severe, they should seek medical attention immediately.

If using the acyclovir eyedrops, patients may experience some local irritation, such as mild pain or stinging. If the irritation is severe, or if patients experience a loss of vision from using the eyedrops, they should seek medical attention immediately.

As with any medication for an infection, patients should monitor their condition and contact their provider if they do not notice an improvement or if they are feeling worse. Even if patients have no signs of a herpes infection, it is still possible to spread the virus to others during sex. Patients should talk with their doctor about ways to keep from spreading the virus.

Dr. DeKorte is director of pharmacy education and training and manager of clinical pharmacy services at George E. Wahlen Dept VA Medical Center. She also is a clinical assistant professor of pharmacy practice at the University of Utah.