Genital herpes; Fever blisters; Cold sores; HSV-1; HSV-2
No drug can cure herpes simplex virus. The infection may recur after treatment has been stopped, and, even during therapy, a patient can still transmit the virus to another person. Drugs can, however, reduce symptoms and improve healing times.
Antiviral drugs called nucleosides or nucleotide analogues are the main drugs used to treat genital herpes. They are taken by mouth. (Acyclovir is also available as an ointment, but the oral form is much more effective.) These drugs limit herpes viral replication and its spread to other cells. They are not cures, however.
Three drugs are approved to treat genital herpes:
When a patient has herpes for the first time, the drug is taken several times a day for 7 -10 days. Then the drugs are used either to suppress the virus or to treat outbreaks.
To treat outbreaks, drug regimens depend on whether it is the first episode or a recurrence and on the medication and dosage prescribed. Most medications need to be taken several times a day. For a first episode, treatment usually lasts 7 - 10 days. For a recurrent episode, treatment takes 1 - 5 days depending on the type of medication and dosage.
To suppress outbreaks, treatment requires taking pills daily on a long-term basis. (Acyclovir and famiciclovir are taken twice a day, valacyclovir once a day.) Suppressive treatment can reduce outbreaks by 70 - 80%. It is generally recommended for patients who have frequent recurrences (6 or more outbreaks per year). Valacyclovir may work especially well for preventing herpes transmission among heterosexual patients when one partner has herpes simplex virus 2 (HSV-2) and the other partner does not. However, valacyclovir may not be as effective as acyclovir or famiciclovir for patients who have very frequent recurrences of herpes (more than 10 outbreaks per year).
Because the frequency of herpes recurrences often diminishes over time, patients should discuss annually with their doctors whether they should stay with drug therapy or discontinue it. Studies suggest that daily drug therapy is safe and effective for up to 6 years with acyclovir, and up to 1 year with valacyclovir or famciclovir.
Side Effects. Nausea and headache are the most common side effects, but in general these drugs are safe. Although there is some evidence these drugs may reduce shedding, they probably do not prevent it entirely. The use of condoms during asymptomatic periods is still essential, even when patients are taking these medications.
Risk for Resistant Viruses. As with antibiotics, doctors are concerned about signs of increasing viral resistance to acyclovir and similar drugs, particularly in immunocompromised patients (such as those with AIDS). Most patients on long-term suppressive drug therapy show few signs of drug resistance. However, patients who do not respond to standard regimens should be monitored for emergence of drug resistance.
In 2002, the U.S. National Institute of Allergy and Infectious Diseases (NIAID) launched the Herpevac Trial for Women to investigate a vaccine for preventing herpes in women who are not infected with HSV-1 or HSV-2. (Previous studies found that the vaccine is not effective for men.) The study of over 7,000 women is currently in its final phases at 40 sites in the U.S. and Canada.
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