Herpes Simplex Virus

What is Herpes Simplex Virus?

Herpes simplex virus is responsible for oral and genital herpes.  These conditions are characterized by the development of vesicular (blister-like) rashes that overlie an erythematous (red) base.  The vesicles tend to form in clusters.  They are painful and highly contagious.  They can also lead to significant psychological discomfort and self-consciousness due to their cosmetic appearance.

Herpes simplex virus type 1 (HSV 1) tends to cause oral herpes whereas herpes simplex virus type 2 (HSV 2) is closely associated with genital herpes – however, either of these viruses can cause oral or genital infection.  HSV1 infection is highly prevalent – a large portion of infected individuals are asymptomatic carriers.  These viruses are spread via oral or genital contact.

Open lesions do not need to necessarily be present as there may be asymptomatic viral sheddingLesions that are crusted over are less likely to be contagious.

What Causes Herpes Simplex Virus?

Herpes simplex virus infection is typically spread via direct contact with open lesions – these lesions are highly contagious.  Asymptomatic viral shedding can also result in viral transmission.  Lesions that are crusted over are less likely to be contagious.

Oral herpes (herpes labialis) is typically acquired by oral contact with the virus in oral or genital secretions of an infected individual.  This type of infection is also commonly known as a “cold sore.”  Genital infections are similarly transmitted by contact with oral or genital lesions or asymptomatic shedding in infected individuals.

When the virus activates it can cause painful vesicular and erythematous lesions in clusters.  These form on the lips and mouth in oral herpes and in the genital region in genital herpes.

How Common is Herpes Simplex Virus?

This condition is exceedingly common in the United States and responsible for a relatively high number of primary care visits.  Severe cases may require referral to a dermatology or infectious disease specialist, especially if first-line measures were unsuccessful.

Greater than 90% of individuals are positive for herpes simplex virus 1 (HSV 1) by age 50.  HSV 1 appears to be more common in women.

About 16% of people age 14-49 are seropositive for herpes simplex virus 2 (HSV 2) in the United States.  The risk of HSV 2 seropositivity increases with age, number of sexual partners, and female gender.

Signs and Symptoms

Symptoms of herpes virus infection typically include the acute development of:

Painful and itchy (pruritic) vesicular lesions in clusters - these usually lie on a red (erythematous base).  Lesions tend to form on the lips and mouth in oral herpes.  They may also occur on the vagina in women and penis and scrotum in men (genital herpes).

Occasionally, patients with develop low-grade fever or malaise in association with their symptoms.  Patients with immunosuppression – HIV/AIDS, cancer, chemotherapy recipients – may have more severe presentation of herpes infection.


The diagnosis of herpes simplex virus is suggested based on symptoms and physical examination.  Painful vesicles in clusters on an erythematous base is classic.  Your doctor will occasionally confirm the diagnosis with PCR (polymerase chain reaction) testing or viral culture.

Rarely, your doctor will check for HSV 1 and HSV 2 antibodies in your serum – this does not usually change management of the condition.

Herpes Simplex Virus Medication and Treatment

Herpes simplex virus is usually treated with antiviral agents such as:

  • Zovirax (acyclovir)
  • Valtrex (valacyclovir)
  • Famvir (famciclovir)

These agents should be started as soon as possible as antiviral therapy within 72 hours of symptoms onset can lead to a reduction of symptoms severity and duration.

The best way to prevent infection is to avoid contact with the virus.  Partners of patients with HSV infection are typically encouraged to use barrier devices (eg, condoms) during oral or sexual intercourse.  Some patients may benefit from chronic suppressive therapy to reduce the risk of reactivation or transmission.


  1. Tyring SK, Baker D, Snowden W. Valacyclovir for herpes simplex virus infection: long-term safety and sustained efficacy after 20 years' experience with acyclovir. J Infect Dis 2002; 186 Suppl 1:S40.

Workowski KA, Bolan GA, Centers for Disease Control and Prevention. Sexually transmitted diseases treatment guidelines, 2015. MMWR Recomm Rep 2015; 64:1.

Popular Herpes Simplex Virus Medications

The above information is an educational aid only. It is not intended as medical advice for individual conditions or treatments. Talk to your doctor, nurse or pharmacist before following any medical regimen to see if it is safe and effective for you.