According to the National Institutes of Health (NIH), most people in the United States are infected with the mouth herpes virus by the age of 20. Not all patients show symptoms. In those who do, symptoms of mouth herpes usually manifest one to three weeks after exposure. The first outbreak symptoms of mouth herpes are characteristically much more severe than the symptoms of subsequent outbreaks.
The term prodrome refers to early or initial symptoms that often precede a full breakout. For mouth herpes, notes Dr. Lawrence Corey of the University of Washington, prodromal symptoms may include tingling, itching, redness, hypersensitivity or soreness in the location where lesions later appear. During the first outbreak, people are usually unaware that they have been infected with mouth herpes and often fail to recognize prodrome as such.
According to a 2008 article in the Journal of Oral Pathology and Medicine, many patients with mouth herpes complain of flu-like symptoms, especially fever, malaise, muscle pain, headache and irritability. Unlike true flu, respiratory symptoms such as cough and cold are not present. Flu-like symptoms of mouth herpes usually last between three days to two weeks and are usually most severe during the first outbreak.
Characteristic clinical manifestations of first-outbreak mouth herpes, says Dr. Corey, include the sudden appearance of clustered, small, painful bumps and fluid-filled blisters over the hard and soft palate, the back of the throat, the tonsils and the lips. Lesions of the tongue, the lining of the cheeks and the gums may appear at the same time or somewhat later.
The lips may be almost completely covered with crops of blisters. After about two days, the blisters rupture, revealing red, ulcerated tissue that eventually becomes grayish. Two to three days later, ulcerations are replaced by a yellowish "crust" that is often itchy as well as painful.
Compared to the lesions in recurrent outbreaks of mouth herpes, first-outbreak lesions are more numerous, widely distributed and take longer to heal (two to three weeks versus seven to 10 days). Recurrent outbreak lesions are usually confined to the lips and face; lesions in the mouth may signal an immunocompromised state.