FFinalistSouthampton · 2027
Sexual health
AKT · Sexual health/Viral STIs

Herpes simplex virus

HSV-1 / HSV-2 (HSV-1 now common genitally)

Overview

Recurrent vesicular/ulcerative genital infection. First episode is the most severe (painful ulcers, systemic features); the virus then establishes latency in sensory ganglia with recurrences.

Recognise

  • First episode: MULTIPLE PAINFUL genital ulcers/vesicles, dysuria, tender inguinal nodes, fever/malaise
  • Recurrences: milder, prodromal tingling, shorter
  • Urinary retention/aseptic meningitis in severe first episodes

Red flags

  • Pregnancy (esp. third-trimester first episode → neonatal herpes risk), urinary retention, immunocompromise, disseminated infection

Differentials & how to tell them apart

Primary syphilissyphilitic chancre is single and PAINLESS; herpes ulcers are multiple and PAINFUL
Aphthous/Behçet ulcersnon-infective, recurrent oral+genital, PCR negative
Chancroidpainful but with suppurative nodes; rare in UK

Investigations

Clinical + HSV PCR (viral swab) of lesion; type the virus (HSV-1 vs 2 — prognostic). Screen other STIs.

Management

Aciclovir 400 mg TDS for 5 days (first episode)

  1. 1First episode: aciclovir 400 mg TDS ×5d (or valaciclovir 500 mg BD ×5d) + saline bathing, analgesia, topical lidocaine. Start within 5 days / while new lesions forming.
  2. 2Recurrences: episodic short-course antiviral, or suppressive therapy (e.g. aciclovir 400 mg BD) if ≥6 recurrences/year.
  3. 3Pregnancy: aciclovir; third-trimester first episode → consider C-section (neonatal herpes risk). Severe/immunocompromised → IV aciclovir.
Aciclovir — first-line antiviral; 400 mg TDS ×5d (first episode)
Valaciclovir / famciclovir — alternatives; valaciclovir 500 mg BD
Saline bathing, analgesia, topical lidocaine — symptomatic

Key points

Neonatal herpes is the feared outcome — highest risk is a first (primary) episode in the third trimester. Condoms reduce but do not eliminate transmission.

Monitor & prognosis

Recurrence frequency; consider suppression; psychological support.

Lifelong latency; recurrences lessen over time (HSV-2 recurs more than HSV-1).

Source: BASHH/NICE CKS Herpes simplex - genital (2025)