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What’s the Difference Between a Chancre and a Chancroid?

A chancre is a symptom of syphilis, while a chancroid is a symptom of the STI of the same name. It’s easy to see why people confuse these two lesions, as they are both caused by sexually transmitted bacterial infections. They also typically appear on the genitals and mouth. However, their root cause is just the start of their differences.

Understanding Chancres

Looking at the key characteristics of chancres can help you distinguish them from chancroids.

  • Cause: Treponema pallidum causes chancres.
  • Diagnosis: Health professionals can diagnose chancres with a blood test.
  • Pain: Chancres are usually painless.
  • Behavior: Chancres don’t discharge pus and bleed.
  • Size: Chancres are small, uniform lesions typically ranging from 0.3 to 0.8 inches.
  • Appearance: Chancres are red lesions which start soft but harden after a few days.
  • Treatment: Chancres heal naturally in four to six weeks without treatment. Treating the underlying condition of syphilis is still very important though.

Understanding Chancroids

Chancroids have the following characteristics:

  • Cause: Haemophilus ducreyi causes chancroids.
  • Diagnosis: There is no blood test for chancroids. Instead, health professionals send samples of the lesions’ fluid away for testing.
  • Pain: Chancroids are painful.
  • Behavior: Chancroids often discharge pus and bleed.
  • Size: Chancroids are large lesions that can substantially vary in size, usually between 0.8 and 2 inches in diameter.
  • Appearance: Chancroids are gray to yellow lesions with soft, moist centers.
  • Treatment: Chancroids require antibiotics to clear up.
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