Lesson
Follow HSV From Entry to Reactivation
HSV replicates at a mucocutaneous site, enters sensory neurons, establishes lifelong latency, and can reactivate along the same neural distribution.
- HSV-1
- HSV-2
- Latency
- Reactivation
- Viral DNA polymerase
Local replication begins
Virus reaches the ganglion
No current eradication therapy
Prodrome can precede vesicles
Separate type from site
HSV-1 commonly causes recurrent herpes labialis, but either HSV type can infect oral or genital sites. Anatomy, exposure, and testing matter more than a type stereotype.
Establish latency
After local replication, HSV travels through sensory axons and persists in a ganglion. Current antivirals do not remove this neuronal reservoir.
Recognize reactivation
Illness, fatigue, stress, tissue trauma, dental work, hormonal change, and strong sunlight can trigger recurrence in susceptible patients, but triggers vary.
Target replication
Acyclovir and related nucleoside analogs require intracellular activation and inhibit viral DNA polymerase. Their value is greatest while viral replication is active.
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Lesson
Distinguish a Familiar Recurrence From a Dangerous Pattern
A typical recurrence is localized and familiar. Diffuse oral disease, eye symptoms, neurologic findings, immune compromise, and atypical lesions change the pathway.
- Prodrome
- Grouped vesicles
- Gingivostomatitis
- Keratitis
- Differential
Grouped vesicles near the lip
Fever and impaired intake
Diagnosis changes treatment
Protect sight and life
Recognize recurrence
Tingling, itching, burning, or pain often precedes grouped vesicles near the vermilion border. Lesions rupture, ooze, crust, and usually heal without scarring in an immunocompetent patient.
Recognize primary disease
Primary oral HSV can produce diffuse painful gingivostomatitis, fever, lymphadenopathy, odynophagia, and reduced intake, especially in children.
Protect the eye and brain
Eye pain, photophobia, visual change, gritty tearing, severe headache, confusion, seizure, or focal neurologic findings require urgent evaluation.
Keep the differential open
Aphthae, impetigo, angular cheilitis, contact dermatitis, trauma, candidiasis, hand-foot-and-mouth disease, and malignancy can mimic parts of the course.
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Lesson
Break Transmission Without Promising Zero Risk
Active lesions and secretions raise transmission risk, but HSV can also shed without visible disease. Precautions reduce risk rather than eliminating it.
- Contact
- Secretions
- Asymptomatic shedding
- Autoinoculation
- Hand hygiene
Avoid during outbreaks
Do not share
Wash after contact
Risk reduction is not zero risk
Avoid high-risk contact
From the first prodromal symptom until complete healing, avoid kissing and oral sex. Do not share items that contact saliva or lesions, including drinks, utensils, towels, razors, cosmetics and lip products. A scab alone is not the endpoint for these outbreak precautions.
Control hand transfer
Do not pick lesions. Wash hands after touching a lesion or applying medication, and keep contaminated fingers away from eyes, genital skin, broken skin, and other people.
Explain shedding
Visible healing lowers risk, but appearance cannot prove that viral shedding has stopped. A lack of lesions does not guarantee zero transmission.
Protect vulnerable contacts
Newborns, immunocompromised people, and children with atopic dermatitis can develop serious disease. Contact precautions and early clinical advice matter.
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Lesson
Treat at the Prodrome, Not at the End of the Episode
Topical products provide modest benefit when started early. Site, age, immune status, schedule, and application burden determine whether they fit.
- Docosanol
- Acyclovir cream
- Penciclovir
- Early treatment
- Application technique
Start immediately
Five times daily until healed
Continue four days
Follow exact product label
Use docosanol within its label
Docosanol 10% treats external facial or lip cold sores. For adults and children at least 12, wash hands and gently rub into the affected area five times daily from the first symptom until healed. For younger children, ask a clinician. Stop and seek advice if the sore worsens or remains unhealed at ten days. Keep away from the eyes and inside the mouth; do not share. Stop for an allergic reaction and seek immediate care. Store at 20-25°C without freezing.
Use acyclovir cream correctly
Acyclovir 5% cream treats recurrent cold sores in immunocompetent patients from age 12. Apply five times daily for four days, beginning with the prodrome or first lesion. Cover clean, dry affected external lip or facial skin, including the lesion margin. Do not use it on genitals or inside the mouth, nose or eye; cream and ointment instructions are not interchangeable. Wash hands before and after use. Avoid other skin products on the treated area during this course. Acyclovir, valacyclovir or ingredient allergy precludes use.
Plan penciclovir frequency
Penciclovir 1% cream is labeled from age 12 for recurrent lip or facial cold sores. Apply every two waking hours for four days, starting with prodrome or the first lesion. Keep it off mucosa and away from the eyes; wash hands afterward. Worsening or non-improving lesions need assessment, including for bacterial infection. Benefit in immunocompromised patients is unestablished. Trials found about half a day less lesion duration than vehicle, not immediate clearance.
Prevent contamination
Use clean hands or a clean cotton-tipped applicator, dab rather than scrub, wash hands afterward, and do not share the product.
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Lesson
Select an Antiviral Regimen by Indication
Oral and buccal therapies can improve convenience and efficacy, but cold sore regimens cannot be borrowed from genital herpes or zoster.
- Valacyclovir
- Famciclovir
- Acyclovir
- Buccal tablet
- DNA polymerase
- Indication-specific dosing
Dose and dose count depend on renal function
Inhibits viral DNA polymerase
Within one hour of prodrome, before lesions
Balance benefit and burden
Use the labeled valacyclovir course
A current label uses valacyclovir 2 grams every 12 hours for one day in adults and patients at least 12 years old. Start at the earliest symptom and do not exceed one day for this indication.
Include famciclovir when appropriate
For immunocompetent adults with recurrent cold sores, famciclovir is 1,500 mg once, started at the first symptom or lesion, with or without food. It is converted to penciclovir. Pediatric efficacy is unestablished; this course is not recommended under age 18. Confirm renal dosing rather than transferring the valacyclovir table: creatinine clearance at least 60 mL/min uses 1,500 mg once; 40-59 uses 750 mg once; 20-39 uses 500 mg once; below 20 uses 250 mg once. Hemodialysis uses 250 mg once after dialysis. This single-dose course is not the HIV-associated orolabial regimen. Product or penciclovir-cream hypersensitivity precludes use; review probenecid because it can raise penciclovir exposure.
Understand prodrug pharmacology
Valacyclovir is converted to acyclovir and improves oral bioavailability. Intracellular acyclovir triphosphate inhibits viral DNA polymerase and terminates DNA-chain elongation.
Use buccal acyclovir as designed
Sitavig is a single 50 mg buccal dose for immunocompetent adults, applied within one hour of prodrome and before visible lesions. Place the flat face on a dry fingertip and the rounded face against the upper gum above the lateral incisor on the symptomatic side. Do not attach it to the lip or cheek. Press through the lip for 30 seconds. Let it dissolve; do not chew, crush, suck or deliberately swallow it. Milk-protein, acyclovir or ingredient allergy precludes use. Verify availability and the dispensed instructions; the linked DailyMed record is an older label.
Manage buccal-tablet displacement
During the first six hours, reposition a detached tablet immediately; use a new tablet if it cannot be repositioned. If swallowed during that period, drink a glass of water and apply a new tablet. After six hours, loss or swallowing does not require replacement. Food and drink are permitted, but avoid gum, brushing, upper dentures and touching the tablet while it adheres; rinse gently for oral cleaning.
Choose route deliberately
Consider onset, recurrence burden, renal function, immune status, swallowing, application burden, access, expected modest benefit, and preference.
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Lesson
Connect Renal Clearance to Dose and Toxicity
Acyclovir exposure rises when renal clearance falls. Hydration, dose adjustment, nephrotoxins, age, dialysis, and immune status shape safety.
- Creatinine clearance
- Acute kidney injury
- Neurotoxicity
- Hydration
- Severe reactions
Adjust the indication-specific dose
Respect heart and kidney limits
Consider accumulation
Standard self-care evidence may not apply
Calculate renal function
Use the current product label and the institution's accepted renal estimate. A normal-looking serum creatinine can hide low clearance in an older or low-muscle-mass patient.
Use the adult cold-sore renal table
For adult valacyclovir cold-sore treatment, creatinine clearance at least 50 mL/min uses two 2 g doses twelve hours apart; 30-49 uses two 1 g doses; 10-29 uses two 500 mg doses. Separate each two-dose regimen by twelve hours. Below 10, give one 500 mg dose. Do not extend treatment beyond one day. Give the recommended dose after hemodialysis. The label lacks data for pediatric patients with clearance below 50 mL/min/1.73 m²; do not automatically apply the adult table.
Protect the kidney
Dehydration, excessive dose, rapid high exposure, existing kidney disease, and nephrotoxins increase acyclovir crystal nephropathy and acute kidney injury risk.
Recognize neurotoxicity
Confusion, agitation, hallucinations, tremor, myoclonus, or seizures during treatment can reflect accumulation and require urgent evaluation.
Escalate serious host and skin findings
Current valacyclovir labeling includes severe cutaneous reactions and TTP or HUS in specific severely immunocompromised high-exposure settings. Stop valacyclovir immediately for a painful rash involving mucosa, a progressive severe rash or suspected TTP/HUS, and obtain urgent assessment. Renal decline also requires prompt review.
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Lesson
Support Healing Without Damaging the Barrier
Comfort measures and trigger reduction can help, but caustic remedies and unproven supplements can delay effective care.
- Cool compress
- Pain relief
- Lip barrier
- Sun trigger
- Lysine
Support comfort
Do not layer products over acyclovir cream
Use with a compatible treatment plan
Do not replace proven care
Use gentle comfort care
Cool compresses, adequate intake, and age-appropriate analgesia can improve comfort. Bland lip protection may help when compatible with the treatment plan, but do not layer it on an area being treated with acyclovir cream: that label excludes other skin products there during treatment. Avoid picking or peeling the crust.
Avoid tissue injury
Alcohol, bleach, acids, aggressive exfoliation, and other caustic home remedies can worsen pain, delay healing, and obscure secondary infection.
Address sunlight triggers
For patients with sun-triggered recurrences, use broad-spectrum SPF 30 or higher lip protection when compatible with the active treatment, plus shade and other sun protection. AAD recommends this approach, but the 2015 Cochrane review found natural-sunlight prevention evidence uncertain despite benefit in experimental ultraviolet-exposure studies. Do not promise that sunscreen will prevent recurrences.
Counsel on supplements honestly
Lysine is commonly used, but current evidence does not establish it as a reliable substitute for antiviral treatment or suppression. Review product quality, cost, interactions, and kidney or reproductive considerations.
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Lesson
Escalate by Burden, Host, and Complication
Frequency, severity, functional impact, immune status, atopic dermatitis, eye symptoms, duration, and infection determine prevention and referral.
- Suppressive therapy
- Eczema herpeticum
- Immune compromise
- Secondary infection
- Pregnancy and pediatrics
Consider suppressive planning
Test and treat earlier
Urgent systemic care
Know the red flags
Measure recurrence burden
Document episode frequency, duration, pain, missed work or school, triggers, psychosocial effect, and response. Frequent or disabling disease can justify clinician-directed suppression or pre-exposure therapy.
Separate suppression from episodic treatment
Daily oral suppression can reduce recurrences, but it requires a clinician-selected regimen and periodic reassessment. The 2015 Cochrane review found a small average preventive benefit from longer-term oral antivirals; brief preventive courses and topical prevention had less certain or inconsistent results. AAD identifies six or more yearly episodes as a reason to seek care, while pain, complications and functional burden can justify earlier review. Neither the book's frequency threshold nor an episode count alone determines treatment.
Recognize eczema herpeticum
Painful monomorphic vesicles or punched-out erosions spreading across atopic dermatitis, with or without fever, require immediate systemic antiviral treatment and same-day specialist assessment. Periocular involvement also needs same-day ophthalmology; do not wait for eye pain or a confirmatory swab to arrange urgent care.
Protect immunocompromised patients
Prolonged, extensive, atypical, resistant, or disseminated disease warrants testing, systemic therapy, and specialist input rather than routine self-care.
Use product-specific reproductive and pediatric evidence
Do not use retired pregnancy letters or adult self-care dosing for young children. Assess pregnancy timing, lactation, infant contact, age, weight, renal function, and exact labeling.
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Module practice
Check the connections.
Each attempt draws 10 questions from the complete 114 question bank.
Each attempt draws a fresh set and rearranges the answer choices.
References
Current clinical foundation.
Core source material was synthesized with the following contemporary guidance. Verify local policy and current guidance before applying clinical information.
- PCDS Eczema Herpeticum Recognition and Urgent Management
- NICE Atopic Eczema: Eczema Herpeticum Recommendations
- WHO Herpes Simplex Virus Fact Sheet
- NHS Cold Sores: Transmission and Referral
- DailyMed Famciclovir Label
- AAD Cold Sore Overview
- AAD Cold Sore Diagnosis and Treatment
- DailyMed Docosanol 10 Percent Cream
- DailyMed Valacyclovir Label
- DailyMed Acyclovir Cream Label
- DailyMed Penciclovir Cream Label
- DailyMed Buccal Acyclovir Label
- Antiviral Treatment Systematic Review
- Herpes Labialis Prevention Cochrane Review