Synopsis
Approach genital ulcers without relying on appearance alone, exclude urgent herpes and syphilis, recognise LGV, chancroid, donovanosis and mpox, and investigate non-infective disease.
- Most genital ulcers in UK practice are herpes or syphilis, and coinfection means both are tested regardless of appearance.
- Swab fresh lesions for HSV NAAT and obtain syphilis serology with repeat testing after the early window when required.
- Ask exact travel, country of partner, oral and anal exposure, sex-work contact, skin-to-skin networks, systemic symptoms and medicines.
Key red flags
Rapidly spreading genital pain, swelling, crepitus or skin necrosis suggests Fournier gangrene and needs emergency debridement.
Severe anorectal pain, discharge, bleeding, tenesmus and systemic symptoms after rectal exposure resembles inflammatory bowel disease.
Investigation priorities
Identify the most common infectious cause using a swab from a fresh vesicle or ulcer base.
Management branches
A new anogenital ulcer is identified and no single cause has been confirmed.
- Take HSV NAAT, syphilis serology and direct treponemal testing where available before lesion treatment.
- Offer HIV and exposure-site chlamydia and gonorrhoea tests and take a pregnancy test where relevant.
Key medicines
Doxycycline for LGVGive 100 mg orally twice daily for 21 days for confirmed or strongly suspected lymphogranuloma venereum.
Azithromycin for chancroidGive 1 g orally as a single dose when chancroid is diagnosed or strongly supported through specialist sexual-health assessment.