Herpes can cause oral or genital blisters and ulcers, but many infections are mild, atypical, or not noticed at all. A sore's appearance cannot confirm HSV, exclude it, or tell you whether HSV-1 or HSV-2 caused it. 123456
If you have a new oral or genital blister, ulcer, small split in the skin (fissure), or sore that might be herpes, seek assessment while it is still present. Ask whether it can be swabbed with a type-specific HSV nucleic-acid amplification test (NAAT), often called PCR. Lesion samples work best before a sore crusts or starts to heal, and culture becomes less sensitive as lesions heal. 1345
A first recognized episode is not necessarily a new infection. Symptoms can first be noticed long after acquisition, so an outbreak cannot by itself date the infection. 3
The quickest way to use this guide
| Situation | What it can mean | Useful next step |
|---|---|---|
| A new oral or genital blister, ulcer, small split in the skin, or sore | HSV is one possibility, but appearance is not diagnostic. 12345610 | Seek assessment while the lesion can still be examined and swabbed. 1345 |
| Tingling, itching, burning, or pain before a familiar recurrence | This can be a prodrome, but the sensation alone does not diagnose HSV. 23410 | If the diagnosis is uncertain or a lesion appears, seek assessment while the area can still be examined and sampled. 1345 |
| A very mild red patch, erosion, pimple-like spot, or small cut | HSV can be subtle, but these appearances have many other causes. 356 | Do not diagnose it from a photo or checklist; get a new or concerning lesion assessed. 13 |
| No symptoms | Many HSV infections are unrecognized, so absence of symptoms does not exclude infection. 123456 | The Testing guide explains when testing may or may not help without a lesion, including partner and prior-symptom questions. 15 |
| Eye pain, vision change, serious neurologic symptoms, pregnancy/newborn concern, or significant immune suppression | The general symptom pattern is not enough for these contexts. 146789 | Use the urgent or specialist care boundary below. 146789 |
What oral herpes can look and feel like
Oral herpes commonly causes one or more painful blisters or open sores on or around the lips and mouth. A typical episode may begin with tingling, itching, burning, or pain, followed by a bump, fluid-filled blister, ulcer, and crust. Not every stage is visible, and other oral or facial conditions can look similar. 2410
With a new infection, some people also have fever, body aches, headache, sore throat, or swollen lymph nodes. Many people have no symptoms or only mild symptoms. 2
HSV-1 is the usual cause of oral herpes, but HSV-2 can also cause oral infection. A symptom pattern or photograph cannot identify the type. 24
What genital herpes can look and feel like
Genital herpes may cause small raised bumps, fluid-filled blisters, shallow erosions, fissures, or open ulcers around the genitals or anus. Lesions on moist internal surfaces may be seen only as ulcers rather than as intact blisters. 234
Local symptoms can include pain, itching, burning, pain with urination, vaginal or urethral discharge, and tender lymph nodes in the groin. Fever and body aches are more common with a first (primary) infection than with a recurrence, but symptoms alone cannot establish when infection began. 2346
Either HSV-1 or HSV-2 can cause genital herpes, and their first genital episodes can look the same. Genital HSV-2 recurs more often on average than genital HSV-1, but type is a laboratory finding, not a visual one. 134 For the fuller type-and-site answer, read HSV-1 vs HSV-2.
First recognized episode versus recurrence
The first episode you notice is the first recognized episode. It may follow recent acquisition, or it may be the first noticed manifestation of an older infection. Current UK guidance says first symptoms can appear years after acquisition. 3
A newly acquired genital infection can cause prolonged illness, severe ulcers, or neurologic involvement, but it can also begin mildly. 1 A recurrence is a later symptomatic reactivation. Recurrences are usually shorter and less severe than a first outbreak, although that is not a promise about one person's next episode. 26
Some recurrences are preceded by a prodrome: local tingling, itching, burning, or pain before a lesion appears. Recurrent genital lesions often return in a favored area, but neither that pattern nor a prodrome proves HSV. 234
Mild, atypical, or unrecognized infection
Many people with HSV have no recognized symptoms. Others have lesions mild enough to be mistaken for a pimple, ingrown hair, small cut, nonspecific red patch, erosion, or fissure. 123456
That range creates two equal errors to avoid:
- A subtle symptom can be HSV, so “it does not look dramatic” is not a rule-out. 123456
- The same subtle symptom can have many other causes, so “HSV can be mild” is not a diagnosis. 1356
No visible outbreak also does not establish that viral shedding or transmission cannot occur. Those are different questions from symptom recognition; the Transmission guide explains the evidence and its limits. 12346
Why appearance cannot diagnose herpes
Classic genital herpes may progress from raised bumps to blisters and ulcers, but many people do not show that full pattern. CDC says diagnosis based only on history and examination of genital, anal, or perianal ulcers is frequently inaccurate. BASHH similarly advises direct confirmation because atypical HSV can resemble nonspecific redness, erosions, or fissures. 13
Genital ulcers also have other infectious and noninfectious causes, and more than one infection can be present at the same time. Evaluation should therefore keep other causes open rather than using HSV as the default answer. 13
This guide cannot identify a described or pictured lesion. If the lesion is present, the useful question is not “does this look exactly like herpes?” but “can it be examined and tested before it heals?”
If a fresh lesion is present, preserve the testing opportunity
Type-specific HSV NAAT/PCR from a lesion is the preferred direct test where it is available. It can identify HSV-1 or HSV-2 at the sampled lesion site. 134
Lesion samples work best before a sore crusts or starts to heal. Culture is less sensitive than NAAT/PCR, particularly for recurrent lesions, and its sensitivity falls as lesions heal. 1345
Do not wait for a blood-test window while a swabbable lesion is present. Seek assessment now, then use the Herpes Testing guide for test choice, timing, negative results, blood antibodies, and confirmation. 135
When to seek prompt or urgent care
A new or first recognized genital sore without the red flags below is generally a prompt-assessment question rather than automatically an emergency. The purpose is to evaluate the cause, preserve testing, and decide whether additional clinical care is needed.
Seek prompt clinical assessment
- You have a new or first recognized genital blister, ulcer, fissure, or painful episode, especially while a lesion is still fresh enough to sample. 1356
- Pain or swelling is making it difficult to pass urine. If you cannot pass urine, use an urgent-care pathway. 3
- Lesions are extensive, unusually deep, atypical, or not healing and you have significant immune suppression. 146
- You are pregnant and have new genital symptoms or a possible new HSV exposure. Tell your prenatal team promptly. CDC recommends specialist management when HSV is acquired in the second half of pregnancy. 168
Use an urgent or emergency pathway
- Eye pain, worsening eye redness, any change in vision, or a red eye that hurts when you look at light needs urgent assessment. Do not use a skin-symptom guide to decide whether the cause is ocular HSV. 7
- Confusion, a seizure, loss of consciousness, new weakness affecting part of the body, or a severe headache with neck stiffness requires emergency assessment. These symptoms have several possible causes and this guide does not attribute them to HSV. 19
- A newborn with documented or suspected exposure to a maternal genital lesion during birth needs specialist follow-up. An unwell newborn needs urgent assessment even if there is no blister or rash. 18
Local urgent-care and emergency routes differ by country. Use the fastest appropriate local service rather than waiting for a lesion diagnosis online.
Where the fuller answer lives
- Use Herpes Testing for lesion swabs, blood-test timing, confirmation, and result interpretation.
- Use HSV-1 vs HSV-2 for the fuller type-and-site comparison and average recurrence differences.
- Use Genital herpes transmission for symptom-free shedding, transmission evidence, and risk reduction.
- Use Herpes Treatment for the purposes and limits of first-episode, episodic, and suppressive antiviral treatment. This symptoms page does not select medicines or regimens.
Evidence and sources
Evidence last checked: 6 September 2026
Evidence scope: Current CDC clinical and patient guidance, the 2025 WHO HSV fact sheet, the 2024 BASHH anogenital-herpes guideline, current NIH guidance for people with HIV, and NHS eye, neonatal, encephalitis, and cold-sore guidance.
Important limitations: No symptom or image checklist can diagnose HSV, date acquisition, or identify HSV type. The urgent-care section identifies boundaries, not management protocols. The NIH source's treatment recommendations for people with HIV are not generalized. NHS service names and phone pathways are not reproduced because care systems differ.
Sources
- CDC. Sexually Transmitted Infections Treatment Guidelines, 2021 (opens in a new tab)Return to citation
- World Health Organization. Herpes simplex virus (opens in a new tab)Return to citation
- Patel R, et al. British Association for Sexual Health and HIV UK national guideline for the management of anogenital herpes, 2024 (opens in a new tab)Return to citation
- National Institutes of Health. Herpes Simplex Virus: Adult and Adolescent Opportunistic Infections (opens in a new tab)Return to citation
- CDC. Screening for Genital Herpes (opens in a new tab)Return to citation
- CDC. About Genital Herpes (opens in a new tab)Return to citation
- NHS. Herpes simplex eye infections (opens in a new tab)Return to citation
- NHS. Neonatal herpes (opens in a new tab)Return to citation
- NHS. Encephalitis: symptoms (opens in a new tab)Return to citation
- NHS. Cold sores (opens in a new tab)Return to citation