Herpes Simplex (Cold Sores or Fever Blisters)

Herpes Simplex


Herpes simplex, commonly called cold sores or fever blisters, may occur once or recur again and again. It’s caused by the herpes hominis virus. There are two kinds of herpes virus: Type 1 and type 2. Type 1 virus causes the cold sores common on the lips and face. Herpes of the genital area is usually caused by type 2 virus.

Herpes simplex begins as a group of small red bumps that blister. You may have noticed itching or discomfort before the rash appeared. The blisters begin to dry up after a few days and form yellow crusts. The crusts gradually fall off and leave slowly fading red areas. The whole process takes about 10 to 14 days. No scars form.

These mild symptoms are typical of recurring herpes simplex. The very first infection with type 1 herpes simplex virus usually happens in childhood. It may go unrecognized, but often it causes fever, general illness, and much local soreness. Once you have a herpes simplex infection, the virus becomes permanently established in your nerve tissue. Recurring herpes results from activation of this virus. Between attacks, it lives quietly in nerve tissue.

Fever and sun exposure are the most common triggering factors for type 1 herpes simplex virus. That’s when cold sores or fever blisters break out. Often, the virus becomes activated without any apparent reason.


Like most other viruses, herpes simplex virus is contagious to people who have never had the infection. Anyone who’s had a fever blister or cold sore on the face is resistant to type 1 virus. Herpes simplex type 1 virus is not very contagious. Close contact such as kissing is necessary to transmit the infection.

Genital herpes (type 2) is usually spread through sexual intercourse and is essentially a disease of adults. It’s highly contagious when in the active stages. Unfortunately, herpes simplex also may be contagious between attacks, when the skin is normal. Recurring herpes is not a reinfection but an activation of virus present in a quiet form in nerve tissue.


We have antiviral medicines that are effective against herpes simplex. These antiviral drugs must be taken by mouth, since ointment forms do not work.

The antivirals interfere with the growth of the virus, and it is important to start treatment early. If you can recognize the early signs of herpes (itching, burning, and redness) before blisters develop—that is the best time to start taking the antiviral drug.

The purpose of the antivirals is to stop the spread of the virus. They do not speed the healing of blisters and scabs already there. For recurring herpes simplex, an antiviral drug is usually given for 3 or 4 days. For the first attack of herpes simplex (primary herpes), antivirals are continued for 7 or 8 days. Side effects from antiviral medicines are rare. If you are pregnant, antivirals (like other medicines) should be taken only if approved by the physician responsible for your prenatal care.

The antivirals are not miracle drugs that banish herpes simplex. If you begin treatment early, they will shorten the course of your disease. After blisters and crusts form, time is required for their healing. Two simple remedies will make you more comfortable while you are recovering from herpes:

1. If there is oozing and crusting, apply cool tap water with a clean cloth for 10 to 15 minutes two or three times a day.

2. Later, when the blisters become yellow and crusted, you can relieve any cracking and dryness with small amounts of plain white petrolatum (Vaseline).

Recurring herpes is usually only an uncomfortable nuisance. One exception is herpes of the eye. Because it may lead to eye damage, you should see an eye doctor (ophthalmologist) immediately. Fortunately, eye involvement is rare with herpes simplex. Herpes simplex around the eye is not dangerous unless it involves the eye.


At present, there are only two ways to prevent recurring herpes simplex: (1) Continuous daily intake of an antiviral drug; and (2) protection from sunlight, if sun is a triggering factor. Taking an antiviral drug on a daily basis over many months may be of benefit if you are plagued with frequent and disabling attacks of herpes.

If sunlight activates your herpes simplex, use a sunscreen on and around your lips when you go outdoors. You can use a heavily pigmented lipstick or a colorless sunscreening lip pomade on your lips and a sun block cream or lotion on the skin around your lips. Both the lip pomade and the sun block should have an SPF (sun protection factor) of at least 15 and preferably over 25.


Fever blisters or cold sores are a harmless infection caused by the herpes hominis virus. Certain antiviral medicines, taken by mouth, will stop the spread of herpes and make attacks less severe if started early in each attack. Fortunately, herpes heals without leaving scars. Sometimes, repeated attacks can be prevented if a triggering factor, such as sunlight, can be found and avoided. Herpes simplex is moderately contagious to people who have never had the infection.

Copyright © 2001 by W.B. Saunders Company. All rights reserved.