Chancroid is a sexually transmitted infection (STI) caused by the Haemophilus ducreyi bacterium. It causes painful open sores (ulcers) in the genital area and swelling of the lymph nodes in the groin.

Chancroid is not common in the United States but is more common in patients who also have human immunodeficiency virus (HIV) infection. Some people who have chancroid are also infected with syphilis or genital herpes (HSV).

Without proper treatment, ulcers require longer periods to heal, which increases the likelihood of getting or transmitting HIV infection.

Successful treatment with antibiotics cures the chancroid infection, relieves symptoms, and prevents transmission to others. In extensive cases, scarring can occur despite successful treatment.