Genital herpes

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Key Point: Genital herpes is a chronic, lifelong viral infection caused by HSV-1 or HSV-2. Antiviral therapy does not eradicate the virus but reduces severity, duration, and frequency of recurrences, and decreases transmission risk. Diagnosis should be confirmed by HSV PCR swab — clinical diagnosis alone is unreliable.

Introduction & Australian Epidemiology

Genital herpes is one of the most prevalent sexually transmitted infections in Australia. HSV-2 seroprevalence in Australian adults is approximately 12–15%, while HSV-1 now accounts for up to 50% of new anogenital herpes diagnoses, predominantly from orogenital transmission in young adults. Many individuals are unaware they are infected due to asymptomatic or unrecognised infection. The ASHM estimates that for every symptomatic case, approximately 2–3 infected individuals remain undiagnosed. Recurrence rates differ by type: HSV-2 genital infection recurs on average 4–6 times per year, compared to approximately 1 recurrence per year for genital HSV-1.

Assessment of Genital Herpes

A thorough history and examination should distinguish primary (first clinical episode) from recurrent disease, as this informs prognosis and antiviral intensity. Assess: lesion morphology, distribution, associated lymphadenopathy, systemic symptoms, and full sexual history.

PRIMARY EPISODE

First Clinical Episode

Multiple painful vesicles/ulcers, bilateral inguinal lymphadenopathy, dysuria, systemic prodrome (fever, myalgia, headache). May last 2–3 weeks untreated.

Most severe; highest viral shedding; risk of urinary retention

NON-PRIMARY FIRST EPISODE

First Episode with Prior Immunity

Less severe than true primary; prior HSV-1 immunity may attenuate HSV-2 presentation. Fewer systemic symptoms and shorter duration.

Serology may show pre-existing type-specific antibody

RECURRENT EPISODE

Reactivation

Prodrome (tingling, burning) precedes lesions 12–24h. Fewer, less painful ulcers; unilateral; shorter duration (5–10 days untreated).

Triggers: stress, fever, UV, menstruation, immunosuppression

Investigations

Essential

HSV PCR — Swab of Active Lesion

Swab base and edges of active ulcer or unroofed vesicle. Types HSV-1 vs HSV-2 — important for prognosis and counselling. Sensitivity 95–99%. Medicare item 69375. Preferred over viral culture.
Essential

Full STI Screen

Syphilis serology (EIA + RPR), HIV Ag/Ab (4th gen), chlamydia/gonorrhoea NAAT, hepatitis B/C serology. Co-infection common in STI presentations.
Available

HSV Type-Specific IgG Serology

Distinguishes HSV-1 from HSV-2 serostatus when swab not possible. Useful for serodiscordant couple counselling. Western Blot is gold standard for equivocal ELISA. Available at reference labs.
Specialist

Aciclovir Resistance Testing (TK Gene Mutation)

Reserve for immunocompromised patients with non-healing lesions despite standard antiviral therapy. Refer to virology reference laboratory.

Approach to Antiviral Therapy for Genital Herpes

Three strategies are used depending on episode type, recurrence frequency, and patient preference:

First Episode Therapy

All patients with a first clinical episode should receive antivirals to reduce severity and duration. Start within 72 hours of symptom onset for maximum efficacy.

Episodic Therapy

For infrequent recurrences (<6/year). Must be taken at the first prodromal symptom — patient should keep medication on hand. Reduces episode duration by 1–2 days.

Suppressive Therapy

For ≥6 recurrences/year, significant psychosocial impact, or serodiscordant relationships. Reduces recurrences ~70–80%, asymptomatic shedding ~90%, and transmission risk ~50%.

Initial Antiviral Therapy — First Clinical Episode

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Valaciclovir 500 mg

Valtrex® · Antiviral prodrug of aciclovir · First-line, first episode

Adult Dose500 mg BD orally

Paediatric20 mg/kg (max 500 mg) BD for adolescents ≥12 years

RouteOral

Duration7–10 days; extend if lesions not healed at day 10

Renal Adj.eGFR 30–49: 500 mg daily; eGFR <30: 500 mg daily; HD: after each dialysis

Hepatic Adj.No adjustment required for mild–moderate impairment

PBS Status✓ PBS General Benefit

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Aciclovir 400 mg

Zovirax® · Nucleoside analogue antiviral · Alternative first episode

Adult Dose400 mg TDS orally; or 200 mg 5× daily

Paediatric250 mg/m² TDS IV (neonatal/disseminated); oral dosing as adult for adolescents

RouteOral (IV 5 mg/kg 8-hourly for severe/CNS disease)

Duration7–10 days

Renal Adj.eGFR 25–50: 400 mg TDS; eGFR 10–25: 400 mg BD; eGFR <10: 400 mg daily

Hepatic Adj.No adjustment required

PBS Status✓ PBS General Benefit

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Severe First Episode: If urinary retention, severe systemic symptoms, or unable to take oral medication — admit and treat with IV aciclovir 5 mg/kg 8-hourly. Switch to oral valaciclovir once tolerating oral intake and improving clinically.

Episodic Antiviral Therapy for Genital Herpes

Episodic therapy suits patients with infrequent recurrences who prefer to treat outbreaks as they occur. The patient must have medication on hand and initiate at the first prodromal sign.

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Valaciclovir 500 mg — Episodic

Valtrex® · Antiviral · First-line episodic recurrence

Adult Dose500 mg BD × 3–5 days; or 1 g daily × 5 days

RouteOral — initiate at prodrome for maximum benefit

Duration3–5 days

Renal Adj.eGFR <30: 500 mg single dose only

Hepatic Adj.No adjustment required

PBS Status✓ PBS General Benefit

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Aciclovir 400 mg — Episodic

Zovirax® · Antiviral · Alternative episodic therapy

Adult Dose400 mg TDS × 5 days; or 800 mg BD × 5 days

RouteOral

Duration5 days

Renal Adj.Reduce dose per eGFR — see product information

Hepatic Adj.No adjustment required

PBS Status✓ PBS General Benefit

Suppressive Antiviral Therapy for Genital Herpes

Indicated for ≥6 recurrences/year, significant psychosocial distress, or serodiscordant relationships. Reassess annually whether suppressive therapy remains necessary.

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Valaciclovir 500 mg — Suppressive

Valtrex® · Antiviral · First-line suppressive therapy

Adult Dose500 mg once daily; 1 g daily if HIV co-infected or ≥10 recurrences/year

RouteOral

DurationOngoing — reassess annually; trial off after 12 months to assess recurrence frequency

Renal Adj.eGFR <30: 250 mg daily

Hepatic Adj.No adjustment required

PBS Status✓ PBS General Benefit

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Aciclovir 400 mg — Suppressive

Zovirax® · Antiviral · Alternative suppressive therapy

Adult Dose400 mg BD

RouteOral

DurationOngoing with annual review

Renal Adj.eGFR <30: 200 mg BD or 400 mg daily

Hepatic Adj.No adjustment required

PBS Status✓ PBS General Benefit

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Serodiscordant Couples: Suppressive valaciclovir 500 mg daily reduces HSV-2 transmission by ~50% in heterosexual serodiscordant couples (Corey et al., NEJM 2004). Condom use provides additional risk reduction. Counsel both partners that transmission can still occur.

Suppressive Antiviral Therapy in Late Pregnancy

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Valaciclovir 500 mg — Late Pregnancy

Valtrex® · Antiviral · Suppression from 36 weeks gestation

Adult Dose500 mg BD from 36 weeks gestation until delivery

IndicationPrimary HSV in pregnancy; recurrent genital HSV; known HSV with ≥1 recurrence in pregnancy

RouteOral

SafetySafe throughout pregnancy — no evidence of teratogenicity. Aciclovir 400 mg TDS is an acceptable alternative.

Renal Adj.As per standard adult dose adjustments

PBS Status✓ PBS General Benefit

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Mode of Delivery: Caesarean section is recommended if active genital herpes lesions or prodromal symptoms are present at onset of labour. Primary HSV acquired in the third trimester carries 30–50% neonatal transmission risk — discuss delivery mode urgently with obstetrics. Suppressive therapy does not eliminate transmission risk entirely.

IV-to-Oral Switch Criteria

Clinical improvement — lesions crusting, systemic symptoms resolving, afebrile ≥24 hours, tolerating oral intake
No evidence of CNS involvement, visceral dissemination, or pneumonitis
Switch to oral valaciclovir 1 g TDS to complete course; for HSV encephalitis: complete full 14–21 day IV course before step-down

Monitoring Parameters

Day 5–7

First episode: Review to confirm lesion healing. If incomplete at day 10, extend antiviral therapy. Confirm HSV type from PCR result and document for long-term management planning.

3 months

Review recurrence frequency — determine suppressive vs episodic strategy. Discuss psychosocial impacts and partner notification. Review full STI screen results.

12 months

Suppressive therapy: Trial off therapy to reassess recurrence frequency. Renal function check if on long-term valaciclovir with CKD. Many patients experience reduced recurrence frequency over time.

Ongoing (immunosuppressed)

Monitor for non-healing lesions suggesting aciclovir resistance. If no response after 7–10 days of standard therapy, arrange resistance testing and consider foscarnet (specialist input required).

Special Populations

🤰 Pregnancy

Both valaciclovir and aciclovir are safe throughout pregnancy with no evidence of teratogenicity. Suppressive therapy from 36 weeks is recommended for women with primary HSV acquired in pregnancy or recurrent genital HSV.

Primary HSV (3rd trimester): Neonatal transmission risk 30–50%. Start valaciclovir 500 mg BD immediately and discuss caesarean delivery with obstetrics.
Active lesions at labour: Caesarean section recommended if active lesions or prodromal symptoms present at onset of labour.
Suppression from 36 weeks: Valaciclovir 500 mg daily to reduce viral shedding and recurrence at delivery.

👶 Paediatrics / Neonatal HSV

Neonatal HSV is a medical emergency with high mortality if untreated. Risk is greatest when maternal primary infection occurs in the third trimester.

Neonatal HSV (all forms): IV aciclovir 20 mg/kg/dose every 8 hours — urgent specialist referral required.
Disseminated / CNS disease: 21-day IV course; skin/eye/mouth disease requires 14 days.
Children ≥2 years: Oral aciclovir 20 mg/kg/dose (max 400 mg) five times daily for 5–10 days.

🛡️ Immunocompromised

Immunocompromised patients are at risk of severe, prolonged, and atypical HSV disease. Resistance to aciclovir may develop with frequent antiviral exposure.

Mild–moderate disease: Valaciclovir 1 g BD for 5–10 days (higher dose than immunocompetent patients).
Severe or disseminated: IV aciclovir 5–10 mg/kg every 8 hours; step down to oral when clinically improving.
Aciclovir-resistant HSV: Foscarnet IV — specialist consultation essential.
Long-term suppression: Valaciclovir 500 mg–1 g daily in HIV/transplant patients.

🫘 Renal Impairment

Both aciclovir and valaciclovir require dose adjustment in renal impairment. Neurotoxicity (confusion, tremor) may occur if doses are not reduced appropriately.

eGFR 30–49 mL/min: Valaciclovir 500 mg BD for treatment; 500 mg daily for suppression.
eGFR 10–29 mL/min: Valaciclovir 500 mg daily for both treatment and suppression.
eGFR <10 / dialysis: Aciclovir 200–400 mg after each dialysis session; specialist advice recommended.

Aboriginal and Torres Strait Islander Health

Genital herpes has a higher burden in some Aboriginal and Torres Strait Islander communities, compounded by co-infection with syphilis (ongoing multi-jurisdictional outbreak), limited access to sexual health services in remote areas, and barriers to diagnosis including stigma and lack of culturally safe care. HSV co-infection increases HIV and syphilis transmission risk, making management clinically important beyond genital herpes alone.

Access to Antivirals

Valaciclovir is PBS-listed and available in remote community health centres. Ensure adequate antiviral stock. Patients should receive a take-home supply for episodic use at prodrome onset.

Stigma and Disclosure

Engage Aboriginal Health Workers in counselling and partner notification. Use plain language and translated resources. Emphasise that herpes is common and manageable to reduce shame-based barriers to care.

Antenatal Screening

In outbreak-affected regions, ensure antenatal STI screens include syphilis and HIV. Counsel pregnant women with known HSV about suppressive therapy from 36 weeks. Coordinate with Aboriginal maternal health services.

Antibiotic Stewardship (ACSQHC NSQHS Standard 3)

Confirm HSV by PCR before commencing long-term suppressive therapy — empirical suppression on clinical diagnosis alone is not appropriate
Valaciclovir is preferred over aciclovir for most indications due to superior oral bioavailability (54% vs 15–20%) and more convenient dosing, improving adherence
Reserve IV aciclovir for severe primary infection, CNS disease, disseminated or neonatal HSV — do not use IV for uncomplicated recurrent HSV in immunocompetent patients
Do not escalate to foscarnet without virological confirmation of aciclovir resistance (TK gene mutation testing) — resistance is rare in immunocompetent patients (<0.5%)
Annual review of suppressive therapy — consider cessation if recurrence frequency has reduced to <4/year and psychosocial impact is minimal

Follow-Up & Prevention

Partner notification: Counsel on asymptomatic viral shedding — transmission can occur without lesions. Recommend partners seek testing and counselling. Online tool: letthemknow.org.au
Transmission reduction: Consistent condom use reduces transmission ~50%. Suppressive therapy provides additional ~50% risk reduction. Combination approach recommended for serodiscordant couples.
Psychosocial support: Acknowledge emotional impact of diagnosis. Provide written resources (SHINE SA genital herpes fact sheets; Herpes Virus Association). Consider referral to sexual health counsellor.
Ongoing STI surveillance: 6–12-monthly STI screen including syphilis and HIV. 3-monthly for high-risk MSM or PrEP users (ASHM guidelines).
Pregnancy planning: Women with known HSV planning pregnancy should be counselled on late-pregnancy suppression from 36 weeks and mode-of-delivery considerations.

References

01
Australasian Society for HIV, Viral Hepatitis and Sexual Health Medicine (ASHM). Australian STI Management Guidelines — Genital Herpes. Sydney: ASHM; 2021. Available from: https://www.sti.guidelines.org.au
02
Corey L, Wald A, Patel R, et al. Once-daily valacyclovir to reduce the risk of transmission of genital herpes. N Engl J Med. 2004;350(1):11–20. doi:10.1056/NEJMoa035127
03
Workowski KA, Bachmann LH, Chan PA, et al. Sexually Transmitted Infections Treatment Guidelines, 2021. MMWR Recomm Rep. 2021;70(4):1–187.
04
Corey L, Wald A. Maternal and neonatal herpes simplex virus infections. N Engl J Med. 2009;361(14):1376–1385. doi:10.1056/NEJMra0807633
05
Kimberlin DW, Whitley RJ, Wan W, et al. Oral acyclovir suppression and neurodevelopment after neonatal herpes. N Engl J Med. 2011;365(14):1284–1292. doi:10.1056/NEJMoa1003509
06
Patel R, Green J, Clarke E, et al. 2014 UK national guideline for the management of anogenital herpes. Int J STD AIDS. 2015;26(11):763–776.
07
Johnston C, Corey L. Current concepts for genital herpes simplex virus infection: diagnostics and pathogenesis of genital tract shedding. Clin Microbiol Rev. 2016;29(1):149–161.
08
Royal Australian and New Zealand College of Obstetricians and Gynaecologists (RANZCOG). Genital Herpes in Pregnancy. Melbourne: RANZCOG; 2020. Available from: https://www.ranzcog.edu.au
09
Australian Institute of Health and Welfare (AIHW). Sexually Transmitted Infections in Australia 2022. Canberra: AIHW; 2022. Available from: https://www.aihw.gov.au
10
Pharmaceutical Benefits Scheme. PBS Online. Canberra: Australian Government Department of Health; 2024. Available from: https://www.pbs.gov.au