A genital ulcer is an open sore or lesion on or around the genitals, anus, or surrounding skin. In the United States, the two most common causes in sexually active people are genital herpes and syphilis. But not all genital ulcers come from sexually transmitted infections. Injuries, autoimmune conditions, allergic reactions, and even friction from clothing can cause them too.
What a Genital Ulcer Looks Like
Genital ulcers vary widely in appearance depending on what’s causing them. Some are small, shallow, and clustered together. Others appear as a single, firm, round sore. They can show up on the vulva, penis, scrotum, perineum, or around the anus. Some ulcers are painful and some are completely painless, which is actually one of the most important clues to figuring out the cause.
You might also notice swelling in the lymph nodes near your groin, fluid draining from the sore, redness or warmth around the area, or fever. Some ulcers heal on their own within a few weeks, while others persist or come back in cycles.
Sexually Transmitted Causes
The majority of genital ulcers in young, sexually active people are caused by either herpes simplex virus or syphilis. Less common STI-related causes include chancroid, lymphogranuloma venereum, and donovanosis. Each of these produces a distinct type of ulcer.
Genital Herpes
Herpes causes clusters of small, painful, shallow ulcers on a red base, sometimes with fluid-filled blisters. A first outbreak often comes with swollen lymph nodes in the groin and fever. Recurrent outbreaks tend to be milder. Globally, the World Health Organization estimates that over 1 in 5 adults has a genital herpes infection, with roughly 42 million new infections occurring each year.
Syphilis
Syphilis produces a very different picture: a single, painless ulcer with firm, raised edges called a chancre. It’s typically not tender to the touch, which is why people sometimes miss it entirely. The nearby lymph nodes may swell slightly but usually aren’t painful. Without treatment, the infection progresses through more serious stages affecting the heart, brain, and other organs.
Chancroid
Chancroid causes shallow, painful ulcers with ragged, undermined edges and a red border. These sores can vary in size and sometimes merge together. The lymph nodes in the groin become swollen and tender. Chancroid is uncommon in the U.S. but more prevalent in parts of Africa, Asia, and the Caribbean.
Lymphogranuloma Venereum and Donovanosis
Lymphogranuloma venereum starts as a small papule or ulcer that’s often so minor it goes unnoticed. The hallmark is severely tender, painful swelling of the lymph nodes, sometimes with drainage through the skin or swelling in the surrounding tissue. Donovanosis (also called granuloma inguinale) begins as a raised nodule that breaks open into a progressively expanding, velvety, granulating lesion. Unlike most other causes, donovanosis doesn’t produce swollen lymph nodes.
Non-Sexually Transmitted Causes
A genital ulcer doesn’t automatically mean an STI. Several other conditions can produce sores in the same area, and they’re worth knowing about, especially if you haven’t had recent sexual contact or your STI tests come back negative.
Behçet’s disease is an inflammatory condition that causes recurring ulcers in the mouth and on the genitals. The genital sores look similar to mouth sores and can be quite painful. They appear on the scrotum in men and the vulva in women. A diagnosis typically requires oral ulcers that recur at least three times a year plus additional symptoms like genital sores, eye inflammation, or skin lesions.
Crohn’s disease, better known for affecting the digestive tract, can also cause ulcers around the genitals and perianal area. Other non-infectious triggers include contact dermatitis from soaps or hygiene products, lichen planus (an inflammatory skin condition), reactions to certain medications (called fixed drug eruptions), psoriasis, and simple trauma from friction or vigorous sexual activity. Yeast infections can occasionally cause surface breakdown that resembles ulceration.
Benign aphthous ulcers, essentially the same type of canker sore you’d get in your mouth, can also appear on genital tissue without any underlying disease.
Painful vs. Painless: Why It Matters
One of the first things a clinician assesses is whether the ulcer hurts. This simple distinction narrows the possible causes significantly.
- Painless ulcers point toward syphilis (a firm, solitary sore) or lymphogranuloma venereum (a small, easily overlooked lesion).
- Painful ulcers suggest herpes (clustered, shallow sores on a red base), chancroid (ragged-edged sores with tender lymph nodes), or aphthous ulcers.
- Progressive, expanding ulcers that are not particularly painful but have a velvety, granulating appearance suggest donovanosis.
These patterns are useful starting points, but there’s significant overlap. A syphilis chancre can occasionally be mildly tender, and herpes sores can sometimes be subtle enough to miss. Testing is almost always necessary to confirm the cause.
How Genital Ulcers Are Diagnosed
Diagnosis usually starts with a visual examination and a detailed history covering sexual activity, timing, pain level, and any other symptoms. From there, testing depends on what the clinician suspects. Blood tests can detect antibodies to syphilis and herpes. Swabs taken directly from the ulcer can identify herpes virus or bacteria through molecular testing. If STI tests are negative, further workup for autoimmune or inflammatory conditions may follow.
Because more than one infection can be present at the same time, comprehensive testing is standard practice rather than stopping after one positive result.
Treatment Depends on the Cause
There’s no single treatment for genital ulcers because the approach depends entirely on what’s causing them. Bacterial infections like syphilis and chancroid are treated with antibiotics and can be fully cured. Genital herpes can’t be cured, but antiviral medication shortens outbreaks, reduces their severity, and lowers the chance of passing the virus to a partner. For recurring herpes, daily suppressive therapy can significantly reduce how often outbreaks happen.
For non-infectious causes, treatment targets the underlying condition. Behçet’s disease, for example, is often managed with anti-inflammatory medications that help control mouth and genital sores along with joint pain. Ulcers from contact dermatitis or irritation typically resolve once you identify and remove the trigger, whether that’s a new soap, detergent, or clothing material. Aphthous ulcers often heal on their own within one to three weeks.
The Link Between Genital Ulcers and HIV
Genital ulcers of any cause create a break in the skin or mucous membrane, which makes it easier for HIV to enter the body. Research from Johns Hopkins found that people with pre-existing herpes infections who then acquired HIV had higher viral loads than those without herpes. Those elevated viral loads persisted over time, making these individuals more infectious to sexual partners and accelerating disease progression.
This connection runs in both directions. Having HIV increases the frequency and severity of genital herpes outbreaks, which in turn creates more opportunities for HIV transmission to others. Suppressing herpes and treating genital ulcer disease is considered an important element of both HIV prevention and management.