Is It Herpes? Genital Sores & Lumps Compared
Eight causes side by side, the clues that point each way, and the one pattern — a painless ulcer that heals by itself — that should never be left alone.
Part of the Complete Genital Herpes Guide.
Key fact: A painless genital ulcer that heals on its own is the pattern to worry about, not the reassuring one — that is how primary syphilis behaves, and the infection continues after the sore goes. Herpes, by contrast, is usually a painful cluster of blisters, often preceded by a tingle. A swab while the lesion is unhealed is what separates them.
Why guessing is unreliable
Genital ulcers and lumps have a long list of causes, several look similar in the early stages, and the treatments have nothing in common. Clinicians do not diagnose these by appearance alone either — they swab, and often take blood tests, because the consequences of guessing wrong are real.
The most important of those consequences is syphilis. Its first-stage sore is often painless, can be hidden internally, and — critically — heals by itself while the infection stays in the body and progresses. UKHSA reported more than 8,000 infectious syphilis diagnoses in England in 2025, so this is a current UK problem rather than a historical one. A painless genital ulcer that goes away on its own is a reason to get tested, not a reason to relax.
The common causes compared
| Cause | What it looks like | Pain | What settles it |
|---|---|---|---|
| Genital herpes | Clusters of small blisters that break into shallow sores; often recurring in the same place | Usually painful, often with tingling beforehand | Swab from an unhealed lesion |
| Syphilis | Usually a single firm ulcer at the site of infection; may be internal and easily missed | Often painless | Blood test and swab — needs testing even if it has healed |
| Ingrown hair or folliculitis | A spot centred on a hair follicle, sometimes with pus | Tender | Usually settles alone; examination if persistent |
| Genital warts | Fleshy lumps or growths, not ulcers or blisters | Usually painless | Examination — see our genital warts page |
| Molluscum contagiosum | Small firm pearly bumps, often with a dimple in the centre | Painless | Examination |
| Aphthous-type ulcers | Round ulcers with a pale base, like mouth ulcers; not linked to sex | Painful | Examination; recurrent cases need review |
| Friction or fissures | Linear splits or grazes, often after sex or vigorous exercise | Stinging | Heal in days; recurrent fissures need assessment |
| Thrush or eczema | Redness, soreness and itching with no blisters or ulcers | Itchy and sore | Examination — see thrush |
The clues that point one way or another
- Blisters first, then sores, in a cluster — characteristic of herpes
- A single, firm, painless ulcer — think syphilis and get tested, even if it heals
- A tingle or nerve ache before it appears — typical of a herpes recurrence, covered in herpes recurrences
- Recurring in the same spot — suggests herpes reactivating from the same nerve root
- Lumps rather than ulcers — warts or molluscum rather than either
- Itching with no ulcer at all — thrush, eczema or another skin cause
- A new partner recently — lowers the threshold for full sexual health testing whatever the appearance
What happens at a sexual health clinic
A clinic will look at the lesion, swab it if it is unhealed, and usually offer blood tests for syphilis and HIV plus tests for chlamydia and gonorrhoea at the same visit — because more than one infection can be present, and because several are symptomless. Testing is free and confidential, appointments are often available quickly, and you can usually be seen without a GP referral. Home self-sampling kits are also available for some infections.
Go while the lesion is there. A swab is the reliable test for herpes and it needs an unhealed blister or sore. Once everything has crusted over, the opportunity has passed, and a blood test cannot tell you when or where you acquired the virus. If something has appeared today, being seen this week matters.
Chlamydia and gonorrhoea often produce no symptoms at all and can sit alongside anything else — see our chlamydia page.
When to be seen urgently
Seek urgent medical care if you cannot pass urine, have a fever with rapidly spreading redness or swelling, feel severely unwell, have a severe headache with neck stiffness or light sensitivity, or are immunocompromised with a spreading or non-healing sore. Severe pain and swelling around the genitals or perineum with fever needs emergency assessment.
Also get seen, but not urgently, for any sore that has not healed within two to three weeks, an ulcer that keeps returning, a lump that is growing, or any lesion where you are not sure of the cause. Persistent non-healing lesions need examination rather than repeated creams.
What not to do
Do not treat a genital ulcer with leftover antibiotics or antivirals from a previous episode — it can suppress the appearance enough to make diagnosis harder without treating the actual cause. Do not apply antiseptics, tea tree oil or steroid creams to an undiagnosed ulcer; they irritate broken skin and delay healing. And do not wait for it to heal before getting tested, which is the specific mistake that lets syphilis progress unnoticed.
If the answer does turn out to be herpes, your first outbreak covers what to expect and the treatment window, and aciclovir vs valaciclovir covers the medicines.
Frequently Asked Questions
How do I know if a genital sore is herpes?
Herpes characteristically starts as a cluster of small blisters that break into shallow, painful sores, often with tingling beforehand, and it tends to recur in the same place. But several conditions look similar early on, and clinicians do not diagnose by appearance alone — a swab from an unhealed lesion is what settles it.
Can a painless sore be serious?
Yes, and this is the most important point on the page. The first-stage sore of syphilis is often painless, can be hidden internally, and heals by itself while the infection remains and progresses. UKHSA reported more than 8,000 infectious syphilis diagnoses in England in 2025. A painless genital ulcer needs testing even if it has already gone.
Is it herpes or an ingrown hair?
An ingrown hair or folliculitis is usually a single spot centred on a hair follicle, sometimes with a visible hair or pus, and it settles on its own. Herpes typically appears as a cluster of blisters that ulcerate, often with a warning tingle, and recurs in the same area. If a lesion is not healing within a couple of weeks, get it looked at.
Should I wait to see if it heals before getting tested?
No. Waiting is the specific mistake that allows syphilis to progress unnoticed, and it also closes the window for the swab that diagnoses herpes, which needs an unhealed lesion. If something has appeared, being seen while it is still there gives the clearest answer.
What will a sexual health clinic do?
Examine the lesion, swab it if it is unhealed, and usually offer blood tests for syphilis and HIV along with chlamydia and gonorrhoea testing at the same visit, since more than one infection can be present and several cause no symptoms. It is free, confidential, and usually available without a GP referral.
Can I use a cream on it while I wait?
Avoid antiseptics, tea tree oil, steroid creams and leftover antivirals or antibiotics on an undiagnosed ulcer. They irritate broken skin, delay healing, and can blur the appearance enough to make diagnosis harder. Simple measures — plain or salt water, patting dry, loose clothing and paracetamol — are safe while you arrange to be seen.
References
- NHS. Genital herpes. nhs.uk
- British Association for Sexual Health and HIV. UK national guideline for the management of anogenital herpes. bashh.org
- BASHH and Royal College of Obstetricians and Gynaecologists. National UK guideline for the management of herpes simplex virus (HSV) in pregnancy and the neonate (2024 update). journals.sagepub.com
- Royal College of Obstetricians and Gynaecologists. Management of genital herpes in pregnancy. rcog.org.uk
- National Institute for Health and Care Excellence. Clinical Knowledge Summary: Herpes simplex — genital. cks.nice.org.uk
Medical disclaimer: This article is for informational purposes only and does not constitute medical advice. Genital symptoms have several possible causes and herpes is only one of them; diagnosis needs a clinician and usually a swab. Always consult a qualified healthcare professional for diagnosis and treatment. In a medical emergency, call 999.