A genital sore is a break in the skin or mucous membrane, often appearing as a lesion, blister, or ulceration. While these physical changes are concerning, their underlying causes are numerous and varied. Some sores indicate a transmissible infection, but others result from common skin conditions or minor external trauma. Understanding the different categories of causes is essential for appropriate evaluation and care.
Infectious Causes: Sexually Transmitted Infections
Genital sores caused by sexually transmitted infections (STIs) have distinct characteristics related to the specific pathogen. The herpes simplex virus (HSV), including types 1 and 2, is a frequent viral cause. It initially presents as tingling or itching, followed rapidly by small, fluid-filled blisters that cluster on a reddened base. These blisters rupture, leaving painful, superficial ulcers that typically crust over and heal within several weeks. The virus establishes latency in nerve cells, meaning outbreaks can recur, though subsequent episodes are often milder.
Bacterial infections produce different features. Primary syphilis, caused by the bacterium Treponema pallidum, manifests as a chancre: a single, firm, non-tender ulcer. This sore has a clean base and a characteristic indurated, or hardened, border. Because it is painless and can be hidden, it often goes unnoticed. Although the chancre heals, the infection remains in the body and progresses to later stages if left untreated.
Chancroid, caused by Haemophilus ducreyi, begins as a small, painful bump that develops into a soft, tender ulcer with ragged edges. Unlike the firm sore of syphilis, chancroid ulcers are typically quite painful and may be accompanied by severely swollen and tender lymph nodes in the groin region. Lymphogranuloma Venereum (LGV), caused by specific strains of Chlamydia trachomatis, often starts as a small, painless papule or ulcer. The most notable symptom of LGV is the subsequent development of severely tender, inflamed, and draining lymph nodes in the groin.
Non-Infectious Dermatological and Inflammatory Conditions
Genital lesions are not exclusively tied to transmissible pathogens; a range of chronic skin diseases and inflammatory responses can also affect the area. Lichen sclerosus is a long-term inflammatory condition that commonly affects the skin around the vulva and anus. It produces distinctive patches of white, thin, and crinkled skin, and this tissue is exceptionally fragile. The intense itching associated with this condition often leads to scratching, which creates fissures, erosions, and ulcers that resemble sores.
Common chronic inflammatory conditions, such as psoriasis and eczema, can also manifest genitally. Genital psoriasis often appears as smooth, well-defined, bright-red plaques because the warm, moist environment prevents the typical silvery scale from forming. Eczema, or atopic dermatitis, causes a dry, intensely itchy rash. Scratching this rash results in irritated and broken skin that may look like a sore.
A fixed drug eruption is an immune-mediated reaction to a systemic medication. This reaction involves the recurrent appearance of one or more lesions, often on the genitalia, in the exact same location each time the specific drug is taken. These lesions are sharply demarcated, round or oval patches that can blister or ulcerate. Common culprits include certain antibiotics and pain relievers, and the lesions fade slowly, often leaving a residual area of darker pigmentation.
Local Irritation and Physical Trauma
Many genital sores are caused by acute external factors that disrupt the delicate skin barrier rather than disease. Contact dermatitis is inflammation caused by direct exposure to an irritant or allergen, which is common in the genital area due to moisture and friction. Irritant contact dermatitis results from harsh soaps, perfumes, detergents, or prolonged contact with sweat, causing immediate burning, redness, and sometimes blistering or erosions. Allergic contact dermatitis may arise from components in topical medications, latex in condoms, or certain hygiene products, causing a delayed but intense rash.
Physical trauma is another frequent non-infectious cause, often resulting from friction or mechanical injury. Vigorous sexual activity, tight-fitting clothing, or prolonged physical activity can cause friction burns, presenting as redness, swelling, and superficial breaks in the skin. Shaving or hair removal methods can also lead to lesions, such as folliculitis, where inflamed hair follicles form small, pus-filled bumps that may rupture and create an open lesion.
Guidance on Seeking Medical Attention and Diagnosis
Any new or unexplained genital sore warrants professional medical evaluation, as timely and accurate diagnosis is necessary to prevent potential complications. Seek care immediately if the sore is accompanied by systemic symptoms, such as fever, chills, or severely swollen lymph nodes, or if the lesion is intensely painful. Furthermore, any sore that does not begin to heal within a few days or that recurs should be examined by a healthcare provider.
The diagnostic process begins with a thorough visual examination and a detailed discussion of symptoms and recent exposures. To determine the cause, a provider may perform specific laboratory tests. If a viral cause is suspected, a swab from an active ulcer can be sent for virologic testing, such as polymerase chain reaction (PCR), which identifies the genetic material of the pathogen. Blood tests are also frequently used to screen for syphilis or detect antibodies to HSV, indicating past exposure. Communicating openly about the onset of symptoms, sexual history, and use of medications is paramount for correct diagnosis and appropriate management.