Viral Infections of the Oral Cavity: Clinical Features and Management

Viral infections of the oral cavity range from familiar cold sores and childhood mouth blisters to oral signs of measles, varicella-zoster virus (VZV), Epstein–Barr virus (EBV), cytomegalovirus (CMV) and advanced immune suppression. Recognising the pattern can help a clinician identify the likely cause, assess hydration and systemic illness, reduce transmission, and act quickly when a patient needs urgent care.

This clinical medicine revision guide expands the supplied teaching slides into a practical approach for students and frontline health workers. A mouth lesion alone rarely identifies a virus with certainty: examine the whole patient, ask about timing and exposures, inspect the skin and eyes, and use local diagnostic and referral pathways.

1. What counts as a viral oral lesion?

The oral mucosa can show a primary viral infection, a recurrence of a virus that remains latent in the body, or a lesion associated with altered immunity. Some viruses produce lesions directly in the mouth. Others produce a characteristic systemic illness in which a mouth finding is one clue. Salivary-gland swelling, such as mumps parotitis, is important in oral assessment even though it is not an ulcer of the oral lining.

Useful descriptive terms include:

• Vesicle: a small fluid-filled blister. In the mouth it usually ruptures quickly, leaving a shallow, tender ulcer.
• Ulcer: a break in the mucosal surface, often with a yellow-white base and red edge. Painful grouped ulcers can follow viral vesicles, but ulceration has many non-viral causes.
• Enanthem: a rash on a mucosal surface, such as the small oral spots seen in measles.
• Plaque: a raised or adherent patch. A white patch that does not wipe away is different from removable candidal material and deserves a careful differential.
• Papillomatous or verrucous growth: a rough, wart-like lesion that may be associated with human papillomavirus (HPV), although appearance alone cannot confirm the cause.

2. Quick comparison of important viruses

3. Herpes simplex virus: gingivostomatitis and cold sores

HSV-1 is the main cause of oral herpes, although HSV-2 can also affect the mouth. Many infections are unnoticed. When symptoms occur, HSV can produce painful blisters or ulcers and may recur because the virus remains latent in sensory nerves. Oral HSV can spread through contact with sores, saliva or oral skin; transmission is most likely when lesions are active, but appearance alone cannot establish that a person is not infectious.

Primary herpetic gingivostomatitis

Primary infection is especially recognised in young children, though it can occur at any age. After a prodrome of fever, malaise, headache or poor appetite, the patient may develop diffuse red, swollen and tender gums with many small vesicles. The vesicles rupture rapidly and leave painful shallow ulcers on the gingiva, tongue, buccal mucosa, palate, lips or perioral skin. Cervical or submandibular nodes may be tender. Pain can make a child refuse food and fluids; dehydration is a major practical complication.

Assess how much the patient is drinking and passing urine, whether they can swallow, their alertness, pain, temperature, mucosal lesions and eye or neurological symptoms. The usual diagnosis is clinical. Lesion PCR may help when the presentation is atypical, confirmation changes management, or the patient is immunocompromised. Serology is rarely useful for diagnosing an acute mouth episode.

Recurrent herpes labialis

A recurrence often begins with tingling, burning, itching or tightness, followed by a cluster of small blisters at the lip edge. The lesions break, crust and heal. Recurrent intraoral HSV more often affects keratinised mucosa such as the hard palate or attached gingiva. Recurrent episodes are often shorter and milder than primary gingivostomatitis. Aphthous ulcers usually occur on movable, non-keratinised mucosa and do not begin as grouped vesicles, but this distinction is not absolute.

Management and counselling

• Hydration and pain relief: encourage frequent small sips and suitable cool fluids; offer soft, non-acidic foods. Use age- and weight-appropriate analgesia according to local guidance. Review for dehydration if intake is poor.
• Antiviral decisions: uncomplicated episodes in an otherwise healthy child are often managed supportively. A clinician may consider oral aciclovir for severe pain or dehydration when treatment can begin early, commonly within about 72 hours of onset. Immunocompromised patients need prompt clinician assessment and may need systemic antiviral treatment. Drug choice and dose depend on age, weight, renal function and severity.
• Avoid unsuitable self-treatment: topical aciclovir is not useful for gingivostomatitis. Do not use numbing gels or give medicines to a young child without checking age-specific safety advice; loss of oral sensation can create additional risk.
• Reduce transmission: avoid kissing and oral contact while lesions are active, do not share items that touch saliva, wash hands after touching lesions, and avoid touching the eyes. Use particular caution around newborns and people with weakened immune systems.

Seek urgent care for inability to maintain fluids, reduced urine, marked lethargy, eye redness or pain, visual change, neurological symptoms, breathing or swallowing problems, or extensive disease in an immunocompromised person.

4. Enteroviruses: HFMD, herpangina and oral ulcers

Hand-foot-and-mouth disease is usually caused by enteroviruses such as coxsackieviruses. It is common in young children, but people of any age can be infected. Fever and sore throat may be followed by painful oral spots or blisters that ulcerate, together with a rash on the palms, soles and sometimes buttocks. The rash can vary, so a patient does not need to have every classic feature. Most cases improve over roughly 7–10 days.

HFMD can spread through respiratory droplets, blister fluid, contaminated objects and surfaces, and stool. Careful handwashing after toileting or changing nappies, cleaning frequently touched surfaces and avoiding close contact during illness help limit spread. Mouth pain may reduce fluid intake, so check hydration and provide supportive symptom relief. There is no routine antiviral treatment for HFMD; antibiotics do not treat the viral illness.

Herpangina

Herpangina is an enteroviral illness with fever and small vesicles or ulcers mainly over the soft palate, uvula and tonsillar pillars. Unlike typical HFMD, a hand or foot rash may be absent. It is usually self-limiting. The clinician should still look for dehydration, severe illness, neurological features or an alternative diagnosis, especially in a very young child or an immunocompromised patient.

5. Varicella-zoster virus: chickenpox and shingles

VZV causes primary varicella (chickenpox) and later reactivation as herpes zoster (shingles). Chickenpox typically produces a generalised itchy rash that evolves from spots to papules and vesicles and then crusts; lesions in several stages may be present at once. Vesicles can occur on oral mucosa and may become painful ulcers. Fever and malaise may accompany the rash. Atypical or breakthrough cases may be less obvious, so use clinical judgement and local testing advice.

Shingles usually causes pain, tingling or skin sensitivity followed by a one-sided grouped rash in a nerve distribution. Trigeminal zoster can affect the face, mouth or eye. Lesions are generally unilateral and do not cross the midline in the same way as a broad bilateral oral process. Pain may begin before the rash. Eye-area involvement, facial weakness, hearing symptoms, disseminated lesions, severe pain or immunosuppression warrants urgent clinician or specialist assessment.

Antiviral treatment is time-sensitive and should be considered by a qualified clinician for selected cases, particularly when disease is severe, facial/ocular, widespread, or the patient is at higher risk of complications. Do not delay urgent eye assessment while arranging oral care. Follow facility guidance for infection prevention, isolation and protection of susceptible high-risk contacts.

6. Measles and rubella: oral clues with public-health importance

Measles and Koplik spots

Measles begins with a febrile respiratory prodrome: cough, coryza and conjunctivitis. Koplik spots may appear on the buccal mucosa as tiny bluish-white points on a red background, often before the characteristic rash spreads from the face down the body. They can be subtle or missed, and their absence does not rule out measles.

Measles is highly contagious and can remain infectious in shared air after the patient leaves. Diagnosis and specimen collection should be coordinated with the public-health pathway. There is no routine specific antiviral for uncomplicated measles; clinical management is supportive and complications require prompt care. Vitamin A use, where indicated, should follow current national or specialist guidance rather than unsupervised dosing.

Rubella

Rubella can cause a mild maculopapular rash, low fever and lymph-node enlargement, particularly behind the ears and at the back of the neck. Fine red spots on the soft palate (sometimes called Forchheimer spots) may occur but are not diagnostic. Any suspected rubella requires clinical and public-health attention because infection during pregnancy can cause serious fetal harm. Avoid relying on an oral sign or a patient's mild symptoms to exclude it; contact the relevant local team for assessment, testing, exposure management and reporting.

7. EBV, CMV and oral findings in immune suppression

Epstein–Barr virus

EBV can cause infectious mononucleosis, with fever, pharyngitis, fatigue and lymphadenopathy. Some patients develop palatal petechiae or tonsillar inflammation. Oral hairy leukoplakia is a separate EBV-associated lesion seen mainly in people with HIV or other immune suppression: it appears as a white or grey, ribbed or shaggy patch, usually on the side of the tongue. It is often not painful and does not usually wipe away. It should prompt assessment of the patient's immune context, but it does not by itself diagnose HIV.

Distinguish it from oral candidiasis, which may leave wipeable plaques with an erythematous surface, and from leukoplakia or other persistent white lesions. A clinician should examine lesions that are atypical, symptomatic, changing or persistent rather than treating every white patch as thrush.

Cytomegalovirus

CMV is widespread and often silent in people with intact immunity. In severe immune suppression, it can cause serious end-organ disease. A persistent, deep or unusually painful oral ulcer may raise CMV among several possible causes, but appearance alone is not enough to confirm it. Consider HSV, trauma, aphthous disease, malignancy and other opportunistic infections. Prompt medical/dental assessment and specialist-directed investigation, which may include biopsy, are more appropriate than repeated empirical medicines.

8. Mumps, HPV and other viral associations

Mumps

Mumps classically causes tender swelling of one or both parotid glands in front of and below the ear, producing fullness near the angle of the jaw. Pain can worsen with chewing, swallowing or sour foods. It is a salivary-gland presentation rather than a primary pattern of mouth ulcers. Consider other causes of parotid swelling and follow local testing, infection-control and public-health guidance.

Human papillomavirus

Oral HPV infection is often asymptomatic. Some HPV types cause benign papillomas or warts, while persistent infection with certain high-risk types is associated with oropharyngeal cancer. A wart-like lesion cannot be typed by inspection. A growing, indurated, ulcerated or persistent oral mass, unexplained neck node, persistent swallowing difficulty or voice change requires clinical evaluation and appropriate referral. Vaccination and prevention advice should follow the current Ugandan immunisation and national health guidance.

Viral lesions in a person living with HIV

Immune suppression may make HSV, VZV and HPV lesions more extensive, more persistent or more recurrent. EBV-associated oral hairy leukoplakia may appear on the lateral tongue. Atypical ulcers may also reflect CMV, medication effects, malignancy or a non-viral infection. Ask permission and use a confidential, non-stigmatising approach when discussing HIV testing. Follow the national testing algorithm and link a patient who tests positive to appropriate HIV care; do not infer a diagnosis from an oral lesion alone.

9. A practical diagnostic approach

History

• When did the lesion begin? Did tingling, fever or a skin rash come first? Is this the first episode or a recurrence?
• Is there pain, difficulty swallowing, drooling, reduced drinking, reduced urine, eye pain, visual change, headache, confusion or breathing difficulty?
• Ask about contact with similar illness, a febrile rash, school or household outbreaks, travel and immunisation history where relevant.
• Ask about immune suppression, HIV status if known, cancer treatment, transplant medicines, pregnancy, chronic illness and current medicines.
• Clarify whether lesions are new, persistent, recurrent, worsening or healing; document previous treatment and response.

Examination

1. Start with general appearance, vital signs, airway, ability to handle secretions, hydration and level of consciousness.
2. Inspect lips, gingiva, tongue, buccal mucosa, palate, floor of mouth, tonsillar region and salivary-gland areas under good light.
3. Describe the lesions before naming a cause: vesicles or ulcers; grouped or diffuse; unilateral or bilateral; keratinised or non-keratinised site; wipeable or adherent; acute or persistent.
4. Examine the skin, palms, soles, face and eyes; palpate relevant lymph nodes and parotid glands.
5. Look for red flags and determine whether the patient needs supportive care, a focused test, isolation, urgent referral or public-health advice.

Investigations

Typical HFMD, herpangina and uncomplicated HSV gingivostomatitis are often diagnosed clinically. Testing is most useful when the appearance is atypical, severe disease is present, the person is immunocompromised, an outbreak or notifiable disease is suspected, or the result will change treatment or infection-control decisions. Depending on the syndrome and local availability, a clinician may request lesion PCR/swab, measles testing through public health, or specialist investigation of a persistent ulcer or mass. Avoid indiscriminate testing and do not delay isolation or urgent care for a suspected high-consequence infection.

10. Supportive care and safe prescribing principles

• Maintain fluids: offer frequent small sips, oral rehydration solution when appropriate, and cool drinks that the patient can tolerate. Reassess patients who cannot drink adequately.
• Reduce pain and irritation: choose age- and weight-appropriate analgesia according to current local guidance. Soft, cool foods may be easier to tolerate; avoid foods that sting or abrade the lesions.
• Support oral hygiene: gentle brushing and routine mouth care help maintain comfort. Do not scrub ulcers or share toothbrushes, cups or utensils during infectious illness.
• Use antivirals selectively: the indication depends on the virus, severity, immune status and time since onset. Clinician review is particularly important for HSV gingivostomatitis, zoster near the eye, severe varicella or disease in an immunocompromised patient.
• Avoid unnecessary antibiotics: antibiotics do not treat viruses. Prescribe them only when there is evidence of a bacterial complication and follow local antimicrobial guidance.
• Give clear return advice: explain hydration monitoring, worsening symptoms, infection precautions and where to seek urgent help. Arrange review when the diagnosis is uncertain or recovery is not following the expected course.

Do not use a single medicine or dose for every viral mouth lesion. Check age, weight, pregnancy, allergies, renal function, drug interactions and local formularies, and obtain supervision when needed.

11. Infection prevention and public-health responsibilities

Apply standard precautions for every patient, including hand hygiene and appropriate protective equipment for the expected exposure. Keep active lesions covered where practical, avoid unnecessary contact with saliva or blister fluid, clean shared equipment and high-touch surfaces, and safely dispose of contaminated materials. Add transmission-based precautions when the suspected infection requires them under local facility policy.

• HSV: use gloves when contact with lesions or secretions is anticipated; reinforce hand hygiene and avoid touching eyes after touching a lesion.
• HFMD: emphasise soap-and-water handwashing, especially after toileting or nappy changes, and cleaning of toys and shared surfaces.
• Measles: act immediately on suspicion, separate the patient and follow the airborne precautions and reporting pathway available in the facility and district.
• Varicella or zoster: seek infection-prevention advice for widespread disease, exposed susceptible contacts, health-care settings and immunocompromised patients.

Vaccination is a major prevention tool for several viral illnesses. Check the current Uganda Expanded Programme on Immunisation schedule and national guidance rather than relying on schedules from another country. For suspected outbreaks or notifiable illness, follow Ministry of Health surveillance instructions.

12. Red flags requiring urgent referral

13. Common differentials and diagnostic pitfalls

14. Worked clinical examples

Example A: a child with painful widespread mouth sores

A preschool child has fever, swollen tender gums, multiple shallow ulcers on the lips and tongue, and is refusing fluids. Consider primary HSV gingivostomatitis, while checking for HFMD, herpangina and other causes. Assess hydration, urine output, pain, eye symptoms and alertness. Provide suitable analgesia and fluid support; escalate if the child cannot maintain hydration or has complications. A clinician decides whether early antiviral treatment is appropriate.

Example B: fever, cough, red eyes and spots inside the cheek

A child with a febrile respiratory prodrome develops small pale spots on an erythematous buccal mucosa and then a spreading rash. Suspect measles. Separate the patient immediately, follow airborne precautions, alert the clinical and infection-prevention team, and notify the public-health pathway for testing and contact guidance. Do not keep the child in a general waiting area.

Example C: one-sided facial pain and oral blisters

An older adult reports burning pain on one side of the face followed by a unilateral rash and painful oral lesions. Consider trigeminal zoster. Check the eye and vision urgently, assess immune status and disease extent, and arrange clinician-led treatment and follow-up. Eye involvement is an emergency.

Example D: a persistent white patch on the side of the tongue

An adult with immune suppression has a ridged white lateral-tongue patch that does not wipe off. Oral hairy leukoplakia is one possibility, but candidiasis, leukoplakia and other lesions must be considered. Review immune status and medications, arrange appropriate clinical assessment, and investigate persistent or atypical lesions rather than treating by appearance alone.

15. Self-assessment questions

1. Which clinical features are typical of primary herpetic gingivostomatitis, and what complication should be assessed first in a child who will not drink?
2. How can the usual distribution of HFMD lesions help distinguish it from herpangina?
3. What accompanying symptoms and infection-control actions should raise suspicion for measles?
4. Why is unilateral facial or oral zoster concerning when it approaches the eye?
5. What does a non-wipeable, ridged white patch on the lateral tongue suggest, and what should not be inferred from it?
6. When should a mouth lesion be swabbed or investigated rather than diagnosed clinically?
7. Why are antibiotics not routinely indicated for viral mouth ulcers?

Suggested answers

1. Diffuse gingivitis with multiple painful vesicles/ulcers, often with fever and tender nodes; assess hydration and ability to drink, alongside airway, eye and neurological status.
2. HFMD often affects the mouth plus palms/soles and sometimes buttocks. Herpangina is concentrated around the posterior palate and tonsillar pillars and may lack a hand/foot rash.
3. Fever with cough, coryza and conjunctivitis, Koplik spots and a spreading rash; separate the patient, use required airborne precautions and promptly report through local public-health procedures.
4. Trigeminal V1/ocular involvement can threaten vision; eye pain, redness, photophobia or visual change requires urgent assessment.
5. EBV-associated oral hairy leukoplakia is possible, especially in immune suppression; it does not by itself diagnose HIV and other white lesions remain in the differential.
6. When the lesion is atypical, severe, persistent, the patient is immunocompromised, confirmation changes management, or a notifiable infection/outbreak is suspected.
7. Antibiotics act against bacteria, not viruses; use them only when a bacterial complication is supported clinically.

16. Key takeaways

• Viral infections of the oral cavity are best recognised by combining lesion morphology with the history, skin findings, systemic symptoms and immune status.
• HSV commonly causes painful gingivostomatitis or recurrent cold sores; hydration is central in children.
• HFMD and herpangina are usually self-limiting enteroviral illnesses; supportive care and hand hygiene matter.
• Measles is a high-consequence diagnosis: recognise the respiratory prodrome and Koplik spots, isolate promptly and notify through local surveillance procedures.
• Unilateral facial or oral zoster, especially near the eye, needs urgent clinician review.
• Persistent or atypical ulcers, white patches or masses need evaluation for non-viral disease, immune suppression and malignancy.
• Choose antivirals selectively under clinical guidance, avoid routine antibiotics for viral disease, and follow current Ugandan protocols.

Further learning and references

• Supplied revision slides: Viral Infections of the Oral Cavity — useful for the topic outline; compare older teaching slides with current guidance.
• World Health Organization: Herpes simplex virus fact sheet.
• Royal Children’s Hospital Melbourne: HSV gingivostomatitis clinical guideline.
• CDC: About hand, foot and mouth disease.
• CDC: Clinical overview of measles — adapt infection-control and reporting steps to the current Ugandan pathway.
• CDC: Clinical features of varicella (chickenpox).
• CDC: Clinical features of shingles (herpes zoster).
• NIH ClinicalInfo HIV glossary: Oral hairy leukoplakia.
• CDC: Clinical features of mumps.

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Educational note: This article is a study resource. It does not replace individual clinical assessment, supervised practice, current Ugandan guidance or specialist referral. Treat patients within your competence and the protocols of your facility.