What is syphilis?

Syphilis is an infection caused by the bacteria Treponema pallidum. It can lead to life-threatening conditions if it is not treated. Syphilis is a sexually transmitted infection (STI), which means that it is spread by having sex with an infected person. If you have syphilis, you can spread it to others. Both men and women can get the disease. Without treatment, the infection can lead to:

  • Heart disease
  • Nerve disorders
  • Brain damage
  • Mental disorders
  • Blindness
  • Aortic aneurysms

These complications develop over many years.

What are the symptoms of syphilis?

The symptoms of syphilis depend on the stage of the infection. The stages of syphilis are:

Primary syphilis

  • A smooth, red, painless sore — or chancre — develops on a sex organ or in the mouth. (The sore also can develop on the inside the body, where it cannot be seen.) The sore goes away on its own in 1 to 6 weeks.

Secondary syphilis

  • After the chancre goes away, a pinkish, bumpy skin rash may appear on all or parts of the body.
  • Fever, sore throat, body aches, headache, loss of appetite or other flu-like symptoms may appear. These symptoms can be mild and can come and go over 1 to 2 years.
  • This stage is the most contagious of all stages. Approximately 1/3 of untreated individuals with primary syphilis will progress to this second stage. In secondary syphilis, the bacteria have spread in the bloodstream and have reached their highest numbers. Without treatment, up to 1/3 of patients will develop complications of late-stage syphilis.

Latent syphilis

  • With latent syphilis, the infection is not contagious but may affect the heart, brain, nerves, eyes, bones and other parts of the body.

Don’t be fooled by the mild warning signs. If you are worried about syphilis, get checked. Syphilis is a serious disease.

Last reviewed by a Cleveland Clinic medical professional on 04/14/2015.


  • Centers for Disease Control and Prevention. Syphilis Accessed 5/8/2015.
  • Augenbraun M. Chapter 19. Syphilis. In: Klausner JD, Hook EW, III. eds. CURRENT Diagnosis & Treatment of Sexually Transmitted Diseases. New York, NY: McGraw-Hill; 2007. library.ccf.org Accessed 5/8/2015.
  • National Institute of Allergy and Infectious Disease. Syphilis Accessed 5/8/2015.

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