Trusted medical expertise in seconds.

Access 1,000+ clinical and preclinical articles. Find answers fast with the high-powered search feature and clinical tools.

Try free for 5 days
Evidence-based content, created and peer-reviewed by physicians. Read the disclaimer.


Last updated: September 6, 2018

Summarytoggle arrow icon

Chancroid (also known as soft chancre) is a highly contagious sexually transmitted infection (STI) caused by Haemophilus ducreyi. Although chancroid is a rare infection in the US, it may occur in immunocompromised patients and is a common cause of genital ulcers in tropical and subtropical regions. It is characterized by the formation of small, painful ulcers on the genitalia and regional lymphadenopathy. The diagnosis is primarily based on clinical findings and is probable if genital herpes and syphilitic chancre have been ruled out. Culture confirms the diagnosis but is not widely available. Treatment usually involves administration of an antibiotic such as ceftriaxone or azithromycin.


  • Incubation period: typically 4–10 days
  • Clinical features
    • Very painful genital ulcers
      • Deep, small (∼ 10–20 mm in diameter), well-demarcated lesions with a grayish necrotic base
    • Painful inguinal lymphadenopathy
    • An asymptomatic course is more likely in women.

In contrast to chancre, chancroid is often painful: The causative pathogen is Haemophilus du-creyi ("do cry")!


Chancroid is a clinical diagnosis. Microbiological analysis or culture may confirm the diagnosis, but have limited sensitivity and are often time consuming.


The differential diagnoses listed here are not exhaustive.


  1. Hicks CB. Chancroid. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. updated: June 30, 2016. Accessed: March 24, 2017.
  2. Jenkins B, McInnis M, Lewis C. Step-Up to USMLE Step 2 CK. Lippincott Williams & Wilkins ; 2015
  3. Le T, Bhushan V, Bagga HS. First Aid for the USMLE Step 2 CK. McGraw-Hill Medical ; 2009
  4. 2015 Sexually Transmitted Diseases Treatment Guidelines - Chancroid. Updated: June 4, 2015. Accessed: March 24, 2017.