Lesions on the penis can be a sign of a sexually transmitted disease (STD). A non-STD cause of having a blister on your penis is folliculitis that can be the result of friction or irritation. Blisters, sores, or bumps on the genital area may indicate a bacterial or viral STD. Herpes or syphilis, for example, may commence their course with a small blister. It is quite essential to know when the blister appeared for the first time, and whether it followed a sexual contact. Another important aspect is how it looks and whether it produces any symptoms, such as pain or itchiness. The following are some STD-related and non-STD-related causes of having a blister, sore, or wound on your penis.

STD-related causes of having a lesion on your penis

STDs are sexually transmitted diseases that you can get from unprotected vaginal, anal, or oral sex. However, you can acquire infection through non-penetrative sex, too, such as during genito-genital or mouth-genital rubbing. The following are some of the most prevalent STDs that can manifest and appear with a genital blister or sore for the first time.

Genital herpes

Genital herpes is an STD you can get with or without having penetrative sex. There are two different types of herpes simplex viruses – HSV -1 (oral herpes or herpes type 1) and HSV-2 (genital herpes or herpes type 2). Most people with herpes do not experience any symptoms or signs for months or even years after they get infected with the virus. However, if the disease shows initial symptoms, you will see them on an average of 2 to 12 days after exposure. An outbreak of genital herpes may take place with the following signs and symptoms in men:

  • Ulceration and blisters on the penis
  • Itching and pain
  • Enlarged and tender lymph nodes
  • Hay fever
  • Flu-like symptoms
  • Pain while urinating
  • Fatigue
  • Rash

Many people with HSV have recurring herpes. The recurrence of herpes on different body parts happens more frequently after a person's primary infection. Tingling or burning around the genitals before the blisters appear is a sign that individuals with recurring herpes may experience. The routes of infection for herpes are through sharing toys, having unprotected vaginal, anal, or oral sex, and having genito-genital contact with an infected person. 

Genital warts

Genital warts are the result of infection with certain types of human papillomavirus (HPV). HPV is the most common STD worldwide, and most people come in contact with it during their first sexual contacts. Genital warts are soft, irregular growths that appear in the genitals of infected individuals. In men, they can present on the penis, scrotum, groin, thighs, and inside or around the anus. Genital warts are not always easy to notice. Sometimes they are darker than your skin while other times they adopt to your skin color. They might appear in locations that are almost invisible to the naked eye. The are cauliflower-like and may appear alone or in bunches, and various sizes. If left untreated, they might spread and cause significant pain and discomfort. Genital warts may produce the following symptoms:

  • Discharge
  • Itching
  • Bleeding
  • Burning sensation

Genital warts are infectious growths you can get through unprotected vaginal, anal, or oral sex. You can acquire them also through non-penetrative sex, such as genito-genital rubbing. You cannot get genital warts from a person that is infected but is in remission. The most effective method of prevention is HPV vaccination. You can vaccinate yourself whether you're a man or a woman, and at any age with Gardasil and Gardasil 9 vaccines. Other methods of prevention have to do with you and your sexual behavior. Generally, being monogamous and using protection is the least you can do to prevent transmission of the infection to you. 


Syphilis is an STD caused by the bacterium Treponema pallidum. You can get syphilis through unprotected vaginal, anal, or oral sex. Sometimes, you don't need to have penetrative sex to get the infection. Syphilis has four stages and is a genital ulcerative disease that may lead to death if left untreated. Stage one of syphilis presents with a blister that may be anywhere on, in, or around your genitals. The sore that appears with this stage is called a chancre. It is firm, round, and painless. It can also be open and wet. The source of infection is this highly contagious sore that can present anywhere in or around the genitals, anus, and mouth. Therefore, the transmission is simple and does not require penetration. Most of the time, the blister is not visible, and syphilis progresses to the next stages if left untreated. The appearance of the sore represents the primary stage of syphilis. The chancre heals within 3 to 6 weeks without treatment. However, no treatment with antibiotics leads to disease progression. 

Non-STD-related causes of having a lesion on your penis

Sometimes, a sore or a blister might indicate a skin condition. Some of them are contagious, and some aren't. Many skin conditions are the result of bacterial or viral infection, but others are autoimmune. Penile cancer can also appear with a lesion that resembles a blister. The following are some examples of skin conditions that may cause you a blister on your penis:

  • Scabies
  • Chancroid
  • Molluscum contagiosum 
  • Psoriasis
  • Atopic dermatitis
  • Lichen planus
  • Diabetes
  • Penile cancer

How can you know if it's an STD?

Having a blister on your penis can be anything from an STD to a skin condition or even cancer. However, if you are sexually active, you might want to exclude a sexually transmitted infection, first, before thinking of other causes. Today, it is almost effortless to find out whether you have an STD or not. All you have to do is get tested. STD rapid kit tests are widely-used testing methods that allow you to get tested alone at home and have your results in fifteen minutes. They come in discreet delivery packages and with easy-to-understand instructions. It is stressful to think of a million worst-case scenario regarding the blister you just noticed on your genitals. Take control of your sexual health and get tested right away. 

How does an STD start?