The early (prodromal) symptoms in adolescents and adults are nausea, loss of appetite, aching muscles, and headache. This is followed by the characteristic rash or oral sores, malaise, and a low-grade fever that signal the presence of the disease. Oral manifestations of the disease (enanthem) not uncommonly may precede the external rash (exanthem). In children the illness is not usually preceded by prodromal symptoms, and the first sign is the rash or the spots in the oral cavity. The rash begins as small red dots on the face, scalp, torso, upper arms and legs; progressing over 10–12 hours to small bumps, blisters and pustules; followed by umbilication and the formation of scabs.

At the blister stage, intense itching is usually present. Blisters may also occur on the palms, soles, and genital area. Commonly, visible evidence of the disease develops in the oral cavity and tonsil areas in the form of small ulcers which can be painful or itchy or both; this enanthem (internal rash) can precede the exanthem (external rash) by 1 to 3 days or can be concurrent. These symptoms of chickenpox appear 10 to 21 days after exposure to a contagious person. Adults may have a more widespread rash and longer fever, and they are more likely to experience complications, such as varicella pneumonia.

Because watery nasal discharge containing live virus usually precedes both exanthem (external rash) and enanthem (oral ulcers) by 1 to 2 days, the infected person actually becomes contagious one to two days before recognition of the disease. Contagiousness persists until all vesicular lesions have become dry crusts (scabs), which usually entails four or five days, by which time nasal shedding of live virus ceases.

The condition usually resolves by itself within a couple of weeks. The rash may, however, last for up to one month. Chickenpox is contagious starting from one to two days before the appearance of the rash and lasts until the lesions have crusted.

Chickenpox is rarely fatal, although it is generally more severe in adult men than in women or children. Non-immune pregnant women and those with a suppressed immune system are at highest risk of serious complications. Arterial ischemic stroke (AIS) associated with chickenpox in the previous year accounts for nearly one third of childhood AIS. The most common late complication of chickenpox is shingles (herpes zoster), caused by reactivation of the "varicella zoster" virus decades after the initial, often childhood, chickenpox infection.

Shingles may have additional symptoms, depending on the dermatome involved. The trigeminal nerve is the most commonly involved nerve, of which the ophthalmic division is the most commonly involved branch. When the virus is reactivated in this nerve branch it is termed "zoster ophthalmicus". The skin of the forehead, upper eyelid and orbit of the eye may be involved. Zoster ophthalmicus occurs in approximately 10% to 25% of cases. In some people, symptoms may include conjunctivitis, keratitis, uveitis, and optic nerve that can sometimes cause chronic ocular inflammation, loss of vision, and debilitating pain.

"Shingles oticus", also known as Ramsay Hunt syndrome type II, involves the ear. It is thought to result from the virus spreading from the facial nerve to the vestibulocochlear nerve. Symptoms include hearing loss and vertigo (rotational dizziness).

Shingles may occur in the mouth if the maxillary or mandibular division of the trigeminal nerve is affected, in which the rash may appear on the mucous membrane of the upper jaw (usually the palate, sometimes the gums of the upper teeth) or the lower jaw (tongue or gums of the lower teeth) respectively. Oral involvement may occur alone or in combination with a rash on the skin over the cutaneous distribution of the same trigeminal branch. As with shingles of the skin, the lesions tend to only involve one side, distinguishing it from other oral blistering conditions. In the mouth, shingles appears initially as 1–4 mm opaque blisters (vesicles), which break down quickly to leave ulcers that heal within 10–14 days. The prodromal pain (before the rash) may be confused with toothache. Sometimes this leads to unnecessary dental treatment. Post herpetic neuralgia uncommonly is associated with shingles in the mouth. Unusual complications may occur with intra-oral shingles that are not seen elsewhere. Due to the close relationship of blood vessels to nerves, the virus can spread to involve the blood vessels and compromise the blood supply, sometimes causing ischemic necrosis. Therefore, oral involvement rarely causes complications such as osteonecrosis, tooth loss, periodontitis (gum disease), pulp calcification, pulp necrosis, periapical lesions and tooth developmental anomalies.

The earliest symptoms of shingles, which include headache, fever, and malaise, are nonspecific, and may result in an incorrect diagnosis. These symptoms are commonly followed by sensations of burning pain, itching, hyperesthesia (oversensitivity), or paresthesia ("pins and needles": tingling, pricking, or numbness). Pain can be mild to extreme in the affected dermatome, with sensations that are often described as stinging, tingling, aching, numbing or throbbing, and can be interspersed with quick stabs of agonizing pain.

Shingles in children is often painless, but people are more likely to get shingles as they age, and the disease tends to be more severe.

In most cases after one to two days, but sometimes as long as three weeks, the initial phase is followed by the appearance of the characteristic skin rash. The pain and rash most commonly occurs on the torso, but can appear on the face, eyes or other parts of the body. At first the rash appears similar to the first appearance of hives; however, unlike hives, shingles causes skin changes limited to a dermatome, normally resulting in a stripe or belt-like pattern that is limited to one side of the body and does not cross the midline. "Zoster sine herpete" ("zoster without herpes") describes a person who has all of the symptoms of shingles except this characteristic rash.

Later the rash becomes vesicular, forming small blisters filled with a serous exudate, as the fever and general malaise continue. The painful vesicles eventually become cloudy or darkened as they fill with blood, and crust over within seven to ten days; usually the crusts fall off and the skin heals, but sometimes, after severe blistering, scarring and discolored skin remain.

Neonatal herpes simplex is a HSV infection in an infant. It is a rare but serious condition, usually caused by vertical transmission of HSV-1 or -2) from mother to newborn. During immunodeficiency, herpes simplex can cause unusual lesions in the skin. One of the most striking is the appearance of clean linear erosions in skin creases, with the appearance of a knife cut. Herpetic sycosis is a recurrent or initial herpes simplex infection affecting primarily the hair follicles. Eczema herpeticum is an infection with herpesvirus in patients with chronic atopic dermatitis may result in spread of herpes simples throughout the eczematous areas.

Herpetic keratoconjunctivitis, a primary infection, typically presents as swelling of the conjunctiva and eyelids (blepharoconjunctivitis), accompanied by small white itchy lesions on the surface of the cornea.

Herpetic sycosis is a recurrent or initial herpes simplex infection affecting primarily the hair follicle.

Herpes simplex is divided into two types; HSV-1 causes primarily mouth, throat, face, eye, and central nervous system infections, whereas HSV-2 causes primarily anogenital infections. However, each may cause infections in all areas.

Chickenpox, also known as varicella, is a highly contagious disease caused by the initial infection with varicella zoster virus (VZV). The disease results in a characteristic skin rash that forms small, itchy blisters, which eventually scab over. It usually starts on the chest, back, and face then spreads to the rest of the body. Other symptoms may include fever, tiredness, and headaches. Symptoms usually last five to seven days. Complications may occasionally include pneumonia, inflammation of the brain, and bacterial skin infections. The disease is often more severe in adults than in children. Symptoms begin 10 to 21 days after exposure to the virus.

Chickenpox is an airborne disease which spreads easily through the coughs and sneezes of an infected person. It may be spread from one to two days before the rash appears until all lesions have crusted over. It may also spread through contact with the blisters. Those with shingles may spread chickenpox to those who are not immune through contact with the blisters. The disease can usually be diagnosed based on the presenting symptom; however, in unusual cases it may be confirmed by polymerase chain reaction (PCR) testing of the blister fluid or scabs. Testing for antibodies may be done to determine if a person is or is not immune. People usually only get chickenpox once. Although reinfections by the virus occur, these reinfections usually do not cause any symptoms.

The varicella vaccine has resulted in a decrease in the number of cases and complications from the disease. It protects about 70 to 90 percent of people from disease with a greater benefit for severe disease. Routine immunization of children is recommended in many countries. Immunization within three days of exposure may improve outcomes in children. Treatment of those infected may include calamine lotion to help with itching, keeping the fingernails short to decrease injury from scratching, and the use of paracetamol (acetaminophen) to help with fevers. For those at increased risk of complications antiviral medication such as aciclovir are recommended.

Chickenpox occurs in all parts of the world. In 2013 there were 140 million cases of chickenpox and herpes zoster worldwide. Before routine immunization the number of cases occurring each year was similar to the number of people born. Since immunization the number of infections in the United States has decreased nearly 90%. In 2015 chickenpox resulted in 6,400 deaths globally – down from 8,900 in 1990. Death occurs in about 1 per 60,000 cases. Chickenpox was not separated from smallpox until the late 19th century. In 1888 its connection to shingles was determined. The first documented use of the term "chicken pox" was in 1658. Various explanations have been suggested for the use of "chicken" in the name, one being the relative mildness of the disease.

Herpes gladiatorum is characterized by a rash with clusters of sometimes painful fluid-filled blisters, often on the neck, chest, face, stomach, and legs. The infection is often accompanied by lymphadenopathy (enlargement of the lymph nodes), fever, sore throat, and headache. Often, the accompanying symptoms are much more of an inconvenience than the actual skin blisters and rash.

Each blister contains infectious virus particles (virions). Close contact, particularly abrasive contact as found in contact sports, causes the infected blisters to burst and pass the infection along. Autoinoculation (self-infection) can occur through self-contact, leading to infection at multiple sites on the body.

Herpes gladiatorum symptoms may last up to a few weeks, and if they occur during the first outbreak, they can be more pronounced. In recurrences of the ailment, symptoms are milder, even if lesions still tend to occur. With recurrent infections scabs may form at 3 days yet the lesions are still considered infectious up til 6.4 days after starting oral antiviral medications. Healing takes place without leaving scars. It is possible that the condition evolves asymptomatically and sores are never present.

Herpes gladiatorum is one of the most infectious of herpes-caused diseases, and is transmissible by skin-to-skin contact. The disease was first described in the 1960s in the "New England Journal of Medicine". It is caused by contagious infection with human herpes simplex virus type 1 (HSV-1), which more commonly causes oral herpes (cold sores). Another strain, HSV-2 usually causes genital herpes, although the strains are very similar and either can cause herpes in any location.

While the disease is commonly passed through normal human contact, it is strongly associated with contact sports—outbreaks in sporting clubs being relatively common.

Other names for the disease are herpes rugbiorum or "scrumpox" (after rugby football), "wrestler's herpes" or "mat pox" (after wrestling). In one of the largest outbreaks ever among high-school wrestlers at a four-week intensive training camp, HSV was identified in 60 of 175 wrestlers. Lesions were on the head in 73 percent of the wrestlers, the extremities in 42 percent, and the trunk in 28 percent. Physical symptoms sometimes recur in the skin. Previous adolescent HSV-1 seroconversion would preclude most herpes gladiatorum, but being that stress and trauma are recognized triggers, such a person would be likely to infect others.

Characteristics of a viral infection can include pain, swelling, redness, impaired function, fever, drowsiness, confusion and convulsions.

Most individuals with HSE show a decrease in their level of consciousness and an altered mental state presenting as confusion, and changes in personality. Increased numbers of white blood cells can be found in patient's cerebrospinal fluid, without the presence of pathogenic bacteria and fungi. Patients typically have a fever and may have seizures. The electrical activity of the brain changes as the disease progresses, first showing abnormalities in one temporal lobe of the brain, which spread to the other temporal lobe 7–10 days later. Imaging by CT or MRI shows characteristic changes in the temporal lobes (see Figure). Definite diagnosis requires testing of the cerebrospinal fluid (CSF) by a lumbar puncture (spinal tap) for presence of the virus. The testing takes several days to perform, and patients with suspected Herpes encephalitis should be treated with acyclovir immediately while waiting for test results.

Herpesviral encephalitis is encephalitis due to herpes simplex virus.

Herpes simplex encephalitis (HSE) is a viral infection of the human central nervous system. It is estimated to affect at least 1 in 500,000 individuals per year and some studies suggest an incidence rate of 5.9 cases per 100,000 live births. The majority of cases of herpes encephalitis are caused by herpes simplex virus-1 (HSV-1), the same virus that causes cold sores. 57% of American adults are infected with HSV-1, which is spread through droplets, casual contact, and sometimes sexual contact, though most infected people never have cold sores. About 10% of cases of herpes encephalitis are due to HSV-2, which is typically spread through sexual contact. About 1 in 3 cases of HSE result from primary HSV-1 infection, predominantly occurring in individuals under the age of 18; 2 in 3 cases occur in seropositive persons, few of whom have history of recurrent orofacial herpes. Approximately 50% of individuals who develop HSE are over 50 years of age.

The most common diseases caused by acute viral infections are encephalitis, flaccid paralysis, aseptic meningitis, post infectious and encephalomyelitis.

Though caused by different infections, the signs and symptoms of TORCH syndrome are consistent. They include hepatosplenomegaly (enlargement of the liver and spleen), fever, lethargy, difficulty feeding, anemia, petechiae, purpurae, jaundice, and chorioretinitis. The specific infection may cause additional symptoms.

TORCH syndrome may develop before birth, causing stillbirth, in the neonatal period, or later in life.

TORCH syndrome is caused by in utero infection with one of the TORCH agents, disrupting fetal development.

Viral encephalitis is a type of encephalitis caused by a virus.

It is unclear if anticonvulsants used in people with viral encephalitis would prevent seizures.

Mumps is usually preceded by a set of prodromal symptoms including low-grade fever, headache, and malaise. This is followed by progressive swelling of one or both parotid glands. Parotid gland swelling usually lasts about one week. Other symptoms of mumps can include dry mouth, sore face and/or ears and some patients find it difficult to talk. A vaccine has been available since the 1960s.

Anterior uveitis develops in 40–50% of cases with HZO within 2 weeks of onset of the skin rashes. Typical HZO keratitis at least mild iritis, especially if Hutchinson's sign is positive for the presence of vescicles upon the tip of the nose.

Features:

This non-granulomatous iridocyclitis is associated with:

- Small keratic precipitates

- Mild aqueous flare

- Occasionally haemorrhagic hypopion.

HZO uveitis is associated with complications such as iris atrophy and secondary glaucoma are not uncommon. Complicated cataract may develop in the late stages of the disease.

Viral meningitis characteristically presents with fever, headache and neck stiffness. Fever is the result of cytokines released that affect the thermoregulatory neurons of the hypothalamus. Cytokines and increased intracranial pressure stimulate nociceptors in the brain that lead to headaches. Neck stiffness is the result of inflamed meninges stretching due to flexion of the spine. In contrast to bacterial meningitis, symptoms are often less severe and do not progress as quickly. Nausea, vomiting and photophobia (light sensitivity) also commonly occur, as do general signs of a viral infection, such as muscle aches and malaise. Increased cranial pressure from viral meningitis stimulates the area postrema, which causes nausea and vomiting. Photophobia is due to meningeal irritation. In severe cases, people may experience concomitant encephalitis (meningoencephalitis), which is suggested by symptoms such as altered mental status, seizures or focal neurologic deficits.

Babies with viral meningitis may only appear irritable, sleepy or have trouble eating. In severe cases, people may experience concomitant encephalitis (meningoencephalitis), which is suggested by symptoms such as altered mental status, seizures or focal neurologic deficits. The pediatric population may show some additional signs and symptoms that include jaundice and bulging fontanelles.

Mumps is a viral disease caused by the mumps virus. Initial signs and symptoms often include fever, muscle pain, headache, and feeling tired. This is then usually followed by painful swelling of one or both parotid salivary glands. Symptoms typically occur 16 to 18 days after exposure and resolve after seven to ten days. Symptoms in adults are often more severe than in children. About a third of people have mild or no symptoms. Complications may include meningitis (15 percent), pancreatitis (four percent), permanent deafness, and testicular inflammation which uncommonly results in infertility. Women may develop ovarian swelling but this does not increase the risk of infertility.

Mumps is highly contagious and spreads rapidly among people living in close quarters. The virus is transmitted by respiratory droplets or direct contact with an infected person. Only humans get and spread the disease. People are infectious to each other from about seven days before the start of symptoms to about eight days after. Once an infection has run its course, a person is typically immune for life. Reinfection is possible but the ensuing infection tends to be mild. Diagnosis is usually suspected due to parotid swelling and can be confirmed by isolating the virus on a swab of the parotid duct. Testing for IgM antibodies in the blood is simple and may be useful; however, it can be falsely negative in those who have been immunized.

Mumps is preventable by two doses of the mumps vaccine. Most of the developed world includes it in their immunization programs, often in combination with measles, rubella, and varicella vaccine. Countries that have low immunization rates may see an increase in cases among older age groups and thus worse outcomes. There is no specific treatment. Efforts involve controlling symptoms with pain medication such as paracetamol (acetaminophen). Intravenous immunoglobulin may be useful in certain complications. Hospitalization may be required if meningitis or pancreatitis develops. About one per ten thousand people who are infected die.

Without immunization about 0.1 percent to one percent of the population are affected per year. Widespread vaccination has resulted in a more than 90 percent decline in rates of disease. Mumps is more common in the developing world where vaccination is less common. Outbreaks, however, may still occur in a vaccinated population. Before the introduction of a vaccine, mumps was a common childhood disease worldwide. Larger outbreaks of disease would typically occur every two to five years. Children between the ages of five and nine were most commonly affected. Among immunized populations often those in their early 20s are affected. Around the equator it often occurs all year round while in the more northerly and southerly regions of the world it is more common in the winter and spring. Painful swelling of the parotid glands and testicles was described by Hippocrates in the 5th century BCE.

Viral meningitis, also known as aseptic meningitis, is a type of meningitis due to a viral infection. It results in inflammation of the meninges (the membranes covering the brain and spinal cord). Symptoms commonly include headache, fever, sensitivity to light, and neck stiffness.

Viruses are the most common cause of aseptic meningitis. Most cases of viral meningitis are caused by enteroviruses (common stomach viruses). However, other viruses can also cause viral meningitis. For instance, West Nile virus, mumps, measles, herpes simplex types I and II, varicella, and lymphocytic choriomeningitis (LCM) virus. Based on clinical symptoms, viral meningitis cannot be reliably differentiated from bacterial meningitis, although viral meningitis typically follows a more benign clinical course. Viral meningitis has no evidence of bacteria present in cerebral spinal fluid (CSF). Therefore, lumbar puncture with CSF analysis is often needed to identify the disease.

In most causes there is no specific treatment, with efforts generally aimed at relieving symptoms (headache, fever, or nausea). A few viral causes, such as HSV, have specific treatments.

In the United States viral meningitis is the cause of greater than half of all cases of meningitis. From 1988–1999, about 36,000 cases occurred a year. While the disease can occur in both children and adults it is more common in children.

Any potential ocular involvement should be assessed by an ophthalmologist as complications such as episcleritis and uveitis may occur.

Mollaret's meningitis is characterized by chronic, recurrent episodes of headache, stiff neck, meningismus, and fever; cerebrospinal fluid (CSF) pleocytosis with large "endothelial" cells, neutrophil granulocytes, and lymphocytes; and attacks separated by symptom-free periods of weeks to years; and spontaneous remission of symptoms and signs. Many people have side effects between bouts that vary from chronic daily headaches to after-effects from meningitis such as hearing loss and visual impairment, nerve pain and twitches. Symptoms may be mild or severe. Some cases may be short, lasting only 3–7 days, while others last for weeks to months.

While herpes simplex and varicella can cause rash, Mollaret's patients may or may not have a rash. Herpes simplex virus is likely the most common cause of Mollaret's meningitis.

An exanthem or exanthema (from Greek ἐξάνθημα "exánthēma", "a breaking out") is a widespread rash usually occurring in children. An exanthem can be caused by toxins, drugs, or microorganisms, or can result from autoimmune disease.

It can be contrasted with an enanthem.

The signs and symptoms of a vertically transmitted infection depend on the individual pathogen. It may cause subtle signs such as a influenza-like illness and may not even be noticed by the mother during the pregnancy. In such cases, the effects may be seen first at birth.

Symptoms of a vertically transmitted infection may include fever and flu like symptoms. The newborn is often small for gestational age. A petechial rash on the skin may be present, with small reddish or purplish spots due to bleeding from capillaries under the skin. An enlarged liver and spleen (hepatosplenomegaly) is common, as is jaundice. However, jaundice is less common in hepatitis B because a newborn's immune system is not developed well enough to mount a response against liver cells, as would normally be the cause of jaundice in an older child or adult. Hearing impairment, eye problems, mental retardation, autism, and death can be caused by vertically transmitted infections. The mother often has a mild infection with few or no symptoms.

The genetic conditions of Aicardi-Goutieres syndrome are possibly present in a similar manner.

Historically, six "classical" infectious childhood exanthems have been recognized, four of which are viral. Numbers were provided in 1905.

The four viral exanthema have much in common, and are often studied together as a class. They are:

Scarlet fever, or "second disease", is associated with the bacterium "Streptococcus pyogenes". Fourth disease, a condition whose existence is not widely accepted today, was described in 1900 and is postulated to be related to the bacterium "Staphylococcus aureus".

Many other common viruses apart from the ones mentioned above can also produce an exanthem as part of their presentation, though they are not considered part of the classic numbered list:

- Varicella zoster virus (chickenpox or shingles)

- Mumps

- rhinovirus (the common cold)

- unilateral laterothoracic exanthem of childhood

- Some types of viral haemorrhagic fever are also known to produce a systemic rash of this kind during the progression of the disease.

- Tick-borne diseases like Rocky Mountain spotted fever produce a rash that may become extensive enough so as to be classified as exanthemous in as many as 90% of children with the disease.